ICM Blog

Subscribe to ICM Blog feed
Updated: 1 hour 44 min ago

Insights into 2018 Corn Dry Down

Fri, 09/21/2018 - 09:57

Corn and soybean harvest has started across many parts of Iowa. Some areas of the state have swung between warm-dry and cool- wet weather within the last few days. With more rain in the forecast, a few producers may be wondering about how fast corn will dry down in the field in the coming weeks. Last fall we wrote an ICM News article highlighting the factors associated with corn grain dry down. In a nutshell: after the crop has reached maturity, the rate of grain dry down is largely driven by air temperature and relative humidity.

Corn grain dry down is typically not a concern during a warm, dry fall. Grain moisture often reaches near 15% by mid-October. However, with cool, wet weather it may take until early to mid-November to reach 15%.

Simulated dry down of hypothetical mid-September maturing crops during two contrasting weather years 1999 (warm-dry) and 2009 (cool-wet).


Measurements from our field experiments in Ames, Iowa show corn grain moisture to be between 23 and 30% as of September 20th. Assuming 34% grain moisture at black layer, early-September maturing corn should be getting close to 20% moisture, while mid-September maturing corn should be just below 29%. Our projections using historical weather data puts grain moisture in Ames between 18 and 22% by October 1 (Table 1 and Figure 2). Corn grain may not reach 15% moisture until the second week of October. In order to avoid harvest delays, we recommend making plans to dry corn post-harvest, especially if weather shifts back to cool and wet.

Anticipated corn grain moisture dry down for Ames Iowa.


Cooler, wetter weather conditions not only have implications on grain moisture but also grain quality. It should be expected that ear molds will increase and may lead to mycotoxins. Because of this, it is recommended that farmers scout fields and prioritize for early harvest those at highest risk of ear mold proliferation. This is extremely important for late planted, late maturing crops where attaining grain moisture near 15% in the field will become less likely as we move into late October and early November.

Category: Crop ProductionTags: Corncorn harvestdrydownAuthors: Rafael Martinez-FeriaSotirios ArchontoulisMark LichtCrop(s): Corn

Samples of Tar Spot in Corn Needed for Research

Wed, 09/12/2018 - 10:54

The University of Illinois, Urbana, is seeking assistance from its friendly neighbor to the west, the corn-state of Iowa, in locating samples of tar spot in corn. This is part of the university’s new research project investigating the genetic variability of the tar spot pathogen.

Tar spot symptoms are small, black raised spots — that can be circular or oval — and may appear on one or both sides of leaves, leaf sheaths and husks. These spots can be found on both healthy green leaves and dying (brown) tissue. The black spots are surrounded by a tan or brown halo, which can be especially obvious on healthy leaves.

Tar spot of corn is a new corn disease first identified in the U.S. in 2015 in Illinois and Indiana. It has since been confirmed in Iowa, Michigan, Wisconsin and Florida. Researchers haven’t seen data that tar spot in corn directly causes yield loss, however, in research conducted in Mexico and South America, the fungus Monographella maydis follows the tar spot fungus and does cause yield loss.

If you have, or believe that you have a sample of corn tar spot, the University of Illinois would be greatly appreciative of your assistance in helping them with their project. If interested, please collect several leaves showing the symptoms and send them in using this form. Please wrap the leaves in newspaper or dry paper towels and ship in a large envelope. Please ship the samples early in the week. If sending samples from multiple locations, please label them and provide the appropriate information to the form.

Here is an additional permit that will allow the university to receive out of state samples, that should be included in the sample package.

Should you have any question, please contact Diane Plewa, of the University of Illinois Plant Clinic.

“If anyone in the state has any samples of tar spot, it would be great if they could assist the University of Illinois in their research,” said Extension Plant Pathologist and Director of the Iowa State University Integrated Pest Management (IPM) program Daren Mueller. “University collaboration is important to the overall mission of IPM, as it allows us to find better, more efficient solutions to control pests. With tar spot in corn having a presence in Iowa, this research could play a critical role in helping us to be prepared in the event that the pathogen becomes a dominant factor in crop production.”

Category: Plant DiseasesTags: tar spotIPMfungusCornAuthors: Ethan StoetzerDaren MuellerCrop(s): Corn

2018 Labor Day Palmer amaranth tour

Mon, 09/03/2018 - 08:53

It's Labor Day weekend, that means it's time for me to see what's happening at the first three Palmer amaranth infestations in western Iowa. The infestations (Harrison, Fremont, and Page Counties) were first reported in 2013.  Harrison County had two fields (approximately 50 acres) with extensive populations, whereas the other two involved scattered plants located primarily outside of production fields.

In Harrison county it was encouraging to see continuous declines in the number of Palmer amaranth escapes.  I didn't find any plants during a brief jaunt into the corn field.  In previous years an area filled with abandoned equipment had always contained a significant Palmer amaranth infestation. This area had been cleaned out and reseeded to perennial grass (Figure 1).  While there were a few, late-season escapes producing seed, in future years the established sod should prevent future Palmer escapes.  There were also a few Palmer amaranth along the road edge, but fewer than in past years.  Stop one on this year's tour was encouraging, now it was time to follow the loess hills south to Fremont county (Figure 2) and determine the state of Palmer amaranth in the southwest corner of Iowa.

Unfortunately, the news in the southwest corner of the state was not as encouraging as in Harrison County.  Initially I was happy to see a ditch that had been filled with Palmer in 2017 was now dominated by kochia and waterhemp.  I suspect this shift was due to natural succession rather than any practices implemented by the county or landowners.  The original infestation in Fremont County was found in a seed company's show plots, and the company has taken efforts (hand roguing and spraying) the past two years to eliminate these plants.  There were a few escapes outside of the plots, but far fewer than in earlier years (Figure 3). Things went downhill quickly after those two observations.  A sweet corn patch across the road has been a playground for Palmer the previous three years, and 2018 was no different (Figure 4).  It is disheartening to think how many millions of seed are being produced in this half acre plot, and where those seeds will move to.  While pondering this, the county sheriff stopped by to inquire if I was lost.  While explaining what I was up to, it was clear he was wondering what kind of person doesn't have anything better to do on a three day weekend than drive around western Iowa looking for weeds.  

The final stop was in Page County. At this location the Palmer is located on the grounds of an ag retailer and in an adjacent field.  Because of wet conditions, I didn't venture into the corn; but the waterways in the field that harbored Palmer in previous years were clean.  There have always been a few escapes around the grounds of the retailer, but it was obvious the company had made efforts to manage the population. This year those efforts weren't apparent, and there were more and larger plants scattered across the grounds than I had observed before.

In summary, if I were to rate the management efforts at the three sites, I would give a thumbs up to Harrison County, and thumbs down to the other two. Early detection and eradication should be the objective for managing new infestations of weeds. It is encouraging to see improvements in management at the Harrison County site where eradication will be most difficult due to the size of this infestation at detection.  Eradication should be  easier at the other sites because of their limited size, but efforts there appear to be lacking.  I hope that in 20 years we don't look back and say "sure wish we would have gone after the Palmer when it was first found".

Previous summaries
2017 Tour
2016 Tour
2015 Tour

Figure 1.  Palmer escape in newly seeded area at Harrison County site.

Figure 2.  Loess hills overlook from Waubonsie State Park in Fremont County. I didn't spot any Palmer in the valley below.


Figure 3.  Palmer escapes outside of show plots in Fremont County.

Figure 4.  Palmer amaranth fulfilling its potential in Fremont County.


Category: WeedsTags: palmer amaranthAuthor: Bob Hartzler

Banner year for the weedy cukes

Sat, 08/25/2018 - 10:10

The finding of mile-a-minute weed near Knoxville, and the subsequent request for reports of additional infestations, has led to a flurry of calls regarding potential findings. Fortunately, none of the reports have been positive, but we appreciate people paying attention to plants in the landscape and notifying us when they spot something suspicious.

Mile-a-minute weed.

While a variety of weeds have been reported, by far the plants most frequently mistaken for mile-a-minute weed have been wild cucumber and burcucumber.  Both of these plants are annuals native to Iowa.  They are frequently found on banks of waterways and roadsides.  They both produce tendrils that allow them to climb other plants and structures to heights of 25 ft.  Burcucumber is more prone to move into crop fields than wild cucumber, and is a significant management issue due to prolonged emergence, tolerance to herbicides, and ability to interfere with harvest.


While the weedy cucumbers have similar growth habits, differences in leaf shape and fruit structure make it easy to differentiate the two species.  Wild cucumber has star-shaped leaves with five lobed leaves, whereas burcucumber has three to five shallow lobes that are much less prominent than those on wild cucumber.  Leaves of both species are up to seven inches wide. The leaves and stems of burcucumber are densely hairy, whereas wild cucumber has smooth stems. Leaves of mile-a-minute weed are triangular in shape, and the stems and petioles have small, sharp thorns.

Wild cucumber leaf.

Burcucumber leaf


Hairy stem of burcucumber.

The fruit of wild cucumber is a spiny structure about two inches long, resembling a small cucumber. Burcucumber produces a cluster of single seeded fruit covered with stiff, sharp hairs.  Each fruit is about ½ to ¾ inch in length.

Wild cucumber fruit.

Cluster of burcucumber fruit.

This has been a banner year for both weedy cucumbers, and they can be seen along many roadsides across Iowa. I suspect the above average temperatures and rain in June favored the growth of the native vines this summer.   It is too late to control them except with manual removal.  Plants in the Ames area have not produced viable seed at the time of writing this article, so removal would reduce problems in future years. Next year, monitor areas with current infestations and implement control strategies in early summer.  Both species are tolerant of 2,4-D.  Glyphosate, dicamba, or triclopyr can be used, but caution is required to avoid damaging other sensitive plants in the area.

Category: WeedsTags: burcucumberwild cucumbermile-a-minute weedAuthor: Bob Hartzler

2018 State Fair Weed ID Contest Results

Wed, 08/15/2018 - 12:40

Another contest is in the books, and once again we provided a sufficient challenge to prevent anyone from earning a perfect score.  In the Professional Division, two-time defending champion Cindy Recker was narrowly edged out by Karen Stiles, last year’s winner in the General Division. Both Cindy and Karen correctly identified 32 out of 35 weeds, but we awarded Karen first place since she correctly identified more of the weeds in the ‘Professional’ category.  The top five in the Professional were separated by four points.

Karen Stiles, champion in the Professional Division.

In the General Division, two recent graduates of ISU’s Agronomy Department finished in the top two places.  Casey Engen was first, whereas Sarah Streigel finished a close second.  In the Future Agronomists division, William Crow edged out Aiden Anderson for the Blue Ribbon.  These two Future Agronomists finished in fourth and fifth place in 2017, showing the value of experience and spending time to learn weeds.

William Crow, champion of Future Agronomist Division.

In an embarrassing moment, I misidentified one of the weeds in the contest, and several contestants in the Professional Division were quick to point out the errors in my ways.  I’ve always said most weed scientists (including myself) are not very good plant taxonomists, but we do know our weeds.  I included a specimen of ladysthumb (Persicaria maculosa), but had taken the lazy route and assumed it was the more common Pennsylvania smartweed (Persicaria pensylvanicum).  The simplest way to differentiate the two is the margin of the ochrea – ladysthumb has hairs on the ochrea margin, whereas Pennsylvania smartweed doesn’t.

As always, we appreciate everybody who takes the time to participate, or those who stop by simply to discuss the weeds.  We hope to see everyone next year; as always, the contest will be held on the first Friday of the greatest state fair in the world!!

Nothing makes me happier than running into former student Katie Demers.  Better luck next year Katie.

John Lawrence, Vice President for Extension and Outreach, did pretty darn good for an Agricultural Economist.

Meaghan and I appreciate the help of Becca Johnson in helping grow the specimens and managing the contest. 

Category: WeedsTags: weed identificationIPMAuthors: Bob HartzlerMeaghan Anderson

4-H Youth appreciate value of in-field learning at FEEL

Wed, 08/08/2018 - 09:27

In June, as part of the annual Iowa 4-H Youth Conference, 13 students participated in the CSI: Crop Science Investigation workshop.

Students who participated were able to travel to the Iowa State University Field Extension Education Laboratory (FEEL) to solve “the mystery of the disappearing yield.” The objective of the program was to help high school students establish a base knowledge in agronomy, horticulture, entomology and plant pathology. Students were then tasked with identifying and implementing management practices that both improved yield and productivity.

According to a post workshop survey done by the members who participated, students  reported moderate to major increases in knowledge in identification and management of insects, diseases and weeds. In addition, a majority agreed that having in-field experience at FEEL was extremely valuable and vital to accomplishing their learning objective on the last day of the workshop. This response indicates the importance of the FEEL facility, and the important role it plays in educating the next generation of farmers, agronomists and agribusiness professionals. On a larger scale, a similar conclusion can be drawn; using the environment as a classroom offers much greater and enhanced learning opportunities that cannot be found in traditional classrooms.

Students reported that they loved learning new things. They learned  not only the correct identification of pest insects, diseases and weeds, but also how to manage these issues and solve problems. If anything could be changed, students wanted to spend even more time in the plots out at FEEL.

All of the students surveyed plan to attend college, with more than half of the students entering into post-secondary education within the next two years. Many will be entering into an agricultural major.

“An advantage of a workshop like this is that the youth get to work with ISU Field Agronomists and other ISU staff,” said Crop Sciences Youth Education Specialist Maya Hayslett. “They get to interact with professionals in the field while doing authentic hands-on learning in an actual crop field.”

Category: Crop ProductionTags: 4-HFEELcrop scoutingYouth educationWeedsIPMInsectsAuthors: Ethan StoetzerMaya C Hayslett

Join us for the fall field day at the Southeast Research and Demonstration Farm on September 6, 2018

Fri, 08/03/2018 - 14:43

Mark your calendar for the September 6 Fall Field Day at the Southeast Research and Demonstration Farm near Crawfordsville.

This year’s fall field day will feature the following topics:

  • “A Season in Review” by Myron Rees, Southeast Research Farm Superintendent
  • “Developing Best Management Practices for Farmers New to Growing Cover Crops” by Mark Licht, ISU Extension Cropping Systems Specialist and Alison Robertson, ISU Extension Plant Pathologist
  • “Weed Management Strategies for 2019 and Beyond” by Meaghan Anderson, ISU Extension Field Agronomist
  • “Crop Market Expectation” by Chad Hart, ISU Crop Market Specialist and Extension Economist

Attendees will have an opportunity to discuss concerns and ask questions with each of the speakers at their respective tour stops.

Certified crop advisers (CCAs) can earn 1.5 hours of continuing education credits by attending the fall field day. Registration for the field day will begin at 1:00 p.m., with the field day kicking off at 1:30 p.m. The event is free and open to the public. More information on the fall field day can be found on the event flyer.

The Southeast Research and Demonstration Farm is located at 3115 Louisa-Washington Road, Crawfordsville. To reach the research farm go 1 3/4 miles south of Crawfordsville on Highway 218, then 2 miles east on G-62, then 3/4 mile north.

Category: Crop ProductionTags: best management practicesBMPscover cropherbicideweed managementcrop marketingcrop marketsfall field dayfield dayISU Southeast Research and Demonstration FarmSoutheast Research and Demonstration Farmsoutheast IowaAuthors: Meaghan AndersonVirgil SchmittRebecca VittetoeCrop(s): CornSoybeanCover Crop

Regional Crop Update July 23 to July 31, 2018

Tue, 07/31/2018 - 15:11

Late season weed escapes, off-target herbicide movement, sightings of soybean aphids, and a little bit of frogeye leaf spot were some of the common issues that Iowa State University Extension and Outreach field agronomists saw in fields across the state this past week. Read on for more information about crop conditions and what’s happening in crop fields across the state.

Northwest Iowa   
Paul Kassel (Region 2): “Some of our corn and soybean fields continue to look excellent. The early planted corn looks good and is entering the R4 (dough) stage of development. The later planted corn did not withstand the waterlogged conditions of late June as well and does not look as good. In fact, some of the later planted corn has lower leaves that are beginning to fire. The corn acres that received added nitrogen in early July have regained their green color. However, these acres are behind in development and are in various stages of pre-tassel or early tassel stages. Some of the early planted soybean fields look excellent. The mid- May planted soybean fields are in the R5 (beginning seed) stage. Soybean aphid numbers are so far staying at low levels; however, continue to keep scouting for this pest. The treatment threshold for soybean aphids is 250 aphids per plant on 80% of the plants. Alternatively, you can use the "speed scouting" method, which can be found here. There have been a few more reports of dicamba off-target movement.

Early planted corn in Clay County at the R4 (dough) stage. Photo by Paul Kassel. 

Early planted soybeans in Clay County at the R5 beginning seed) stage. Photo by Paul Kassel. 

North Central Iowa
Angie Rieck-Hinz (Region 3): “Corn averages from R2 (blister) to R4 (dough); however, I have even seen a few fields planted mid-April at early R5 (dent). In many places corn is firing pretty high up the stalk—mostly due to lack of nitrogen and now again, lack of water across the southern part of my area. Maintaining stalk quality will be a challenge this year to get us to harvest. Soybeans are R3 (begin pod) to R5 (begin pod fill). I have had a few reports of aphids. I continue to receive phone calls regarding off-target herbicide movement in soybeans. North Central Iowa received less than a half inch of rain for the past week, with the exception of Northwood, which received 0.79 inches. 

Northeast Iowa
Terry Basol: (Region 4): "The recent weather has provided a nice low stress environment for both the corn and soybeans.  According to the Iowa Mesonet, we received about 1.2 inches of rain from July 15 through July 31 at the NE IA Research and Demonstration Farm near Nashua. Corn ranges mainly from the R2 (blister) to R3 (milk) stage with some fields in the southern edge of my region being at R4 (dough). Soybeans range from R3 (begin pod) to R4 (full pod); however, there are some acres in the far northern area of my region that are just in the early reproductive stages (R1 or R2). Overall, there has been low levels of foliar diseases in both corn and soybeans. I've found some gray leaf spot in corn and Septoria brown spot and frogeye leaf spot in soybeans. On the insect side, soybean aphid levels continue to remain very low for NE Iowa, although It’s important to continue scouting as the recent weather that we’ve had is conducive for population increase of this pest. There have been cases of Bt resistant issues in corn fields with corn rootworms that are being investigated. Other insects that have been found in fields include Japanese beetles, Bird Cherry-Oat aphids in corn, and second generation true armyworms."

Stress Degree Days for Waterloo from May 1 through July 31, 2018. Source: Iowa Mesonet


Southwest and West Central Iowa
Mike Witt (Region 6): “West Central Iowa received little to no rainfall over the last week. Crops are still doing well, but they could use rain and are starting to show signs of water stress or leaf rolling in lighter soils. If this trend of limited moisture continues and the heat of summer returns there is potential for stress issues. Corn is mainly at the R3 (milk) stage. There is the beginnings of nitrogen stress and firing of leaves in the lower canopy of some fields depending on maturity and nutrient availability. Soybeans are in the R3 (begin pod) to R4 (full pod) stages of pod development with a few fields hitting R5 (begin seed). There have been a few reports of soybean aphids around the area. None of the reports or numbers have hit economic thresholds for spraying, but scouting should continue for this pest. Corn rootworm beetles and Japense beetles can also be commonly found in fields. Disease pressures have been limited this year in West Central Iowa with many different diseases present but very few reaching levels that required a fungicide application. It's easy to spot waterhemp and other weeds emerging above the soybean canopy. Take some time now to scout fields for herbicide effectives and for potential weed resistance issues. A trusty hoe is your best bet at this stage of the season for weed control."

Central, East Central Iowa, Southeast, and South Central
Virgil Schmitt (Region 9): “In an unusual turn of events, the area that most needed rain in the last seven days received the most, with the driest area (southwest Lee County) receiving between 1.5 and 2.0 inches of rain with progressively lesser amounts to the north, with areas north of Highway 34 generally receiving less than 0.5 inches of rain. Corn is mostly late R3 (milk) and is generally looking good. Gray leaf spot continues to generate calls and field visits. Soybeans are mostly R4 (full pod) and also looking good. Frogeye leaf spot is showing up. Gray leaf spot, Japanese beetles, and weed escapes dominated calls last week.”

Early lesions of frogeye leaf spot are small, irregular to circular and gray with reddish-brown borders. As the lesions age, the middle area becomes gray to light brown with dark, red-brown margins. Photo by Rebecca Vittetoe. 

Josh Michel (Region 11): “Scattered light showers brought some minor drought relief to some areas, but unfortunately many areas across my region didn’t receive any rainfall. Extreme drought (D3) conditions have now been expanded into three counties in my region (Davis, Van Buren, and Appanoose) according to the most recent drought monitor (released July 26). Pastures, hayfields, and corn fields are really showing signs of drought stress.  Most corn fields are at R3 (milk) and R4 (dough). Most soybean fields are at R3 (begin pod) to R4 (full pod), and overall are looking good despite the lack of precipitation. The majority of my calls last week consisted of drought stressed corn, drought stressed hayfields, gray leaf spot, frogeye leaf spot, Japanese beetles, and off target herbicide damage in soybeans.”

Despite the cooler temperatures over the past week, the dry conditions continue to persist in southern Iowa, and the drought stress is really showing up in fields. Photo by Josh Michel from a  corn field north of Drakesville. 

 Check out the map below to find your local ISU Extension and Outreach field agronomist and find their contact information here!

Map showing the regions and counties field agronomists cover.

Category: Crop ProductionTags: field agronomistscrop updatecrop progressAuthor: Rebecca Vittetoe

Updated FACTS Forecast

Wed, 07/25/2018 - 07:13

Our analysis shows that soybean more has been more adversely affected by the 2018 weather compared to corn. Soybean yield potential has dropped while corn yield potential is still high. We are in the midst of critical corn grain filling now and soybean grain filling will be starting soon. Convergence in the best and worst case scenarios will begin to occur as grain filling continues.

Nitrogen uptake by the corn plant has peaked and nitrogen uptake rates are now approximately 1 pound per acre per day. In the central IA sites you can see the magnitude of nitrogen leaching from the top layer to the bottom. And in the northern Iowa sites you can see the effect of heat on nitrogen accumulation. Overall this analysis revealed that the 2018 is very unique as it falls outside the historical average.

Interestingly, root depths at the central Iowa site are about 4 feet. This is much shallower than they should be at that time of the year. The reason for shallow root depths is the presence of shallower water tables and the lack of rooting ability into saturated soils with limited oxygen.

A change to the FACTS webpage have been made. The soil water and nitrogen and plant water and nitrogen uptake figures now include historical benchmarks. This baseline will help compare the current growing season with the long-term average (or normal year). And evapotranspiration, rooting depth, and soil nitrate status per layer are now included on the summary page.

For more information go to crops.extension.iastate.edu/facts.


Category: Crop ProductionTags: APSIMFACTSyield forecastAuthors: Sotirios ArchontoulisMark LichtCrop(s): CornSoybean

Regional Crop Update July 16 to July 24, 2018

Tue, 07/24/2018 - 15:27

Gray leaf spot, spotting of soybean aphids, and off-target herbicide movement seem to be common and big issues that Iowa State University Extension and Outreach field agronomists saw across the state this past week. Read on for more information about your region’s crop progress and field conditions.

Northwest Iowa   
Joel DeJong (Region 1): “During the last week the NW corner of the state received very little rainfall. But, that is ok considering we are still a long ways above average for the last month. Rivers have returned to within their banks. In areas that have not been too wet, the crops look really good, and wetter areas are showing improved growth now, too. I have not observed many disease lesions anywhere, although I can see and hear airplanes flying. Corn rootworms beetles have emerged, so it is a good time to evaluate root systems for injury. Soybean aphids are just starting to appear in the region, although numbers seem to remain low at this point. Reports from our neighbors to the north have been on an uptrend for a while, so scouting should be on-going now.”

Paul Kassel (Region 2): “Crop development has progressed very well recently, but corn development varies a great deal. Corn fields that were planted in early May on pattern tiled fields are in the blister stage/early milk stage (R2 to R3). Corn fields that were planted in late May on fields that were less well drained are just beginning the pollination process. Many of these later planted fields have severely stunted areas as a result of waterlogged conditions in late June. The soybean crop is developing at a similar rate. The early planted soybean crop is approaching the R4 (full pod). Farmers are considering fungicide application on some of the better looking fields – which is a difficult decision with the current commodity prices. Soybean aphids have been at very low levels; however, farmers are concerned that the soybean aphid populations will develop with the onset of the predicted cooler weather." 

Soybean aphids appeared in this Buena Vista County field this week. Take time to scout for aphids in your fields. Photo by Paul Kassel.

North Central Iowa
Angie Rieck-Hinz (Region 3): “Herbicide efficacy from the group 14 products and dicamba have not been all that good. Waterhemp was large due to adverse conditions delaying spraying of post-applied products. The tops of many waterhemp are dead, but if you look lower on the plant, the plant is still alive and shooting new growth. I have been chasing dicamba off-target complaint calls. I have yet to find any soybeans aphids. In terms of corn, gray leaf spot is present, but the pressure has been relatively low in this area. Rainfall ranged from 0 inches at Rockwell City to just over 2.0 inches at Northwood.” 

Southwest and West Central Iowa
Aaron Saeugling (Region 10): “Conditions are good in SW Iowa right now. Corn is in the R2 (blister) to R3 (milk) stage. Some fungicide applications still being made. Soybeans are in the R2 (full bloom) to R3 (begin pod) with a few in the R4 (full pod) stage. Some areas have received rain in the last few weeks while other areas would welcome an inch or two of rain. Potato leafhoppers have been an issue in some alfalfa fields.” 

Central, East Central Iowa, Southeast, and South Central:
Meaghan Anderson (Region 7): “Crops are continuing to move relatively quickly through reproductive stages in Central and East Central Iowa with corn mostly in the R3 growth stage and soybeans in the R3-R4 growth stage. The cooler temperatures and rainfall for much of East Central Iowa early last week were welcome breaks from the heat and dry conditions. Much of Central (and East Central) Iowa could use a good rain, but the forecast does not look promising for the next week. Problems in the last week have continued to include dicamba or other plant growth regulator injury to soybeans, increasing abundance of gray leaf spot in some corn fields, and concern regarding Japanese beetles defoliating soybeans and eating into corn ears on field edges. Our rootworm entomologist on campus has visited several fields with suspected Bt trait failures across the state and will visit one in central Iowa next week. Now is a good time to check fields for presence of northern or western corn rootworm beetles and dig roots to check for feeding. More information on identifying rootworm beetles, rating root injury, and management options here.”

Rootworm feeding found on some corn roots from a field with a suspected Bt trait failure in Central Iowa. Photo by Meaghan Anderson. 

Adult western corn rootworm found in a corn field in Central Iowa. Western corn rootworms are yellow with a dark head. The females have three black lines on the forewings that do not extend to the wing tip while the forewings of the males often look like a black smudge. Photo by Meaghan Anderson. 

Rebecca Vittetoe (Region 8): “Overall crops are looking really good. Corn ranges from late R2 (blister) to R3 (milk). Gray leaf spot seems to be the biggest issue in corn this year. A lot of fungicide applications seemed to be made last week with some wrapping up this week. Soybeans range from R3 (begin pod) to R4 (full pod). The biggest issues in soybeans seem to be off-target herbicide movement and late season weed escapes. There were some isolated areas that unfortunately received wind and hail damage from the storms that occurred last Thursday.”

Gray leaf spot has moved into the upper canopy in some corn fields in Southeast Iowa. Photo by Rebecca Vittetoe.

Virgil Schmitt (Region 9): “In the area I cover, there was between 0.5 and 2 plus inches of rain, with the most rain being close to HWY 20 and close to the Missouri border. Corn is mostly R3 (milk) and is generally looking good with the exception of gray leaf spot. Soybeans are mostly R3 (begin pod) and generally looking good except for some Septoria brown spot making its way into the mid-canopy in some fields. Call last week were mostly about Japanese beetles, gray leaf spot, and dicamba off-target movement.”

Rainfall totals across the state of Iowa for the past 7 days as of July 23, 2018. Source: http://www.weather.gov

Josh Michel (Region 11): “While some counties in Southeast Iowa received some much needed precipitation last week, unfortunately many areas across my region didn’t receive any last week. Pastures and hayfields continue to show signs of stress from the persistent dry conditions. Most of my area is either moderate (D1) or severe (D2) drought and small area is considered in an extreme drought (D3) according to the most U.S. Drought Monitor (released July 19, 2018). Most corn fields are R2 (blister) and R3 (milk). Corn fields in the region are looking ok, except for those in the driest part of the region. Those fields are showing signs of stress. Soybean fields are at R3 (begin pod) to R4 (full pod), and generally are looking good. In the dry areas, spider mites could become an issue. Calls last week consisted of drought stressed corn, gray leaf spot, alfalfa and soybean defoliation, and group 4 herbicide damage in soybeans.”

Check out the map below to find your local ISU Extension and Outreach field agronomist and find their contact information here!

Map showing the regions and counties field agronomists cover.

Category: Crop ProductionTags: crop updatefield agronomistscrop progressAuthor: Rebecca Vittetoe

Mile-a-minute weed found in Iowa

Mon, 07/23/2018 - 15:36

Mile-a-minute weed (Persicaria perfoliata) is an invasive species in the Polygonaceae (smartweed) family that is native to Asia.  It is believed to have been introduced to the United States in the late 1800’s and early 1900’s, but the initial introductions failed to form permanent infestations.   The plant is suspected to have become permanently established following introduction to a plant nursery in eastern Pennsylvania in the 1930’s or 1940’s, possibly with imported rhododendron plants.  Since then the plant has spread westward; the most recent USDA mapindicates infestations in the mid-Atlantic states west to Ohio and Kentucky.  EDDMapSindicates an infestation in one Indiana county.

A landowner near Knoxville contacted the Marion County Extension office regarding a weed he had been battling for the past three years after a friend tentatively identified the plant as mile-a-minute weed (MAMW).  We, along with a representative from IDALS, visited the site on July 19 to confirm that the weed was indeed the invasive plant not known to be present in Iowa. Once we arrived, it was clear that the plant was indeed MAMW.

Mile-a-minute weed climbing and pulling down ornamental miscanthus at the first known infestation in Iowa.

MAMW has several unique characteristics that differentiate it from other viney weeds in Iowa and simplify its identification.  These traits include: leaves shaped like an equilateral triangle, short, curved spines on stems and petioles, circular ochrea at leaf nodes, and small blue fruit with a single seed produced in clusters. Like most members of the Polygonaceae family, the flowers of MAMW are small, white, and inconspicuous.  The plant is adapted to wet areas with full sun, and frequently invades forest edges, stream banks, and roadsides.  It is not considered a threat to agricultural fields.

The plant is spread locally by birds consuming the fruit, but since the plant is not known to be in the region, it is likely the introduction was facilitated by human activities.  Our best guess is that seed of MAMW was brought to this site via plants purchased from a nursery in a state infested with MAMW.  The infestation was located at the edge of a wooded area and well-maintained gardens.  We did not find presence of MAMW in the wooded area with deep shade. 

Although this was our first encounter with MAMW, it was easy to see why the plant is considered a threat. This infestation was less than a quarter acre in size, but it was highly successful at crowding out existing vegetation. The weight of the plant was pulling down a stand of miscanthus, a species known for establishing monocultures.

There is no easy method to eradicating weed infestations, whether it’s mile-a-minute weed, Palmer amaranth, or Canada thistle. It appears this infestation had been present for at least five years, thus there will be a large seedbank present.  Studies have shown seed can survive for at least eight years, and management will take a long-term commitment.  The landowner has used postemergence applications of glyphosate and growth regulator herbicides.  While these are effective, the prolonged emergence patterns will require multiple applications during the growing season.  These products likely will damage other plants in the area, opening the site up for invasion of other weeds or new flushes of MAMW.  The plant has a small root system, so hand pulling is a relatively easy (gloves are recommended due to the spines) and effective way to remove stands.

While this is the first discovery of this invasive species in Iowa, humans are extremely effective at inadvertently moving invasive species to new locations.  If you find MAMW or another weed you suspect to be an invasive species, please contact us for information on identification and management.

Triangular leaf of mile-a-minute weed.



Mile-a-minute weed climbs is capable of smothering plants in infested areas.


Category: WeedsTags: invasive plantsWeedsPersicaria perfoliataAuthors: Bob HartzlerMeaghan Anderson

Regional Crop Update July 9 to July 17, 2018

Wed, 07/18/2018 - 11:18

This past week brought drier conditions across the state. Northern Iowa appreciated the chance to dry out some, but parts of southern Iowa could really benefit from some much needed rain. Check out what Iowa State University Extension and Outreach field agronomists have been seeing in fields across the state over this past week.

Northwest Iowa   
Paul Kassel (Region 2): “Herbicide application to the soybean crop is wrapping up. Weed control with the dicamba products labeled for soybean appear to be working well; however, waterhemp in some of the fomesafen (PPO-inhibitor) treated fields are starting to recover and are not dying. The damage from the waterlogged conditions from the heavy rains in late June is still evident. While there are a lot of corn fields that are looking better, there are still areas in corn fields that have not recovered. The soybean crop on the other hand appears to have recovered from the waterlogged conditions fairly well in most cases. A few farmers replanted some drowned out areas last week. The mid-May planted soybean fields are approaching the early pod stage (R3).”

Corn stunted from waterlogged conditions that is in the V14 stage, compared to the rest of the field which is at VT. Photo by Paul Kassel.  

Northeast Iowa
Terry Basol: (Region 4): “Weather was very favorable for crop development this past week. According to the Iowa Mesonet, we received about 2.5 inches of rain from July 9 through July 14 at the NE IA Research and Demonstration farm near Nashua. In general, most of the corn in my territory has reached VT, with the exception of the late planted corn. Some corn in the southern part of the territory is in the R1(silking) to R2 (blister) stage of development. Overall, soybeans are in the R2 (full bloom) to R3 (begin pod) stage. According to the most recent Iowa Crop Progress & Condition Report  from the National Agricultural Statistics Service (NASS), eight percent of the soybeans in NE Iowa are setting pods. Soybean aphid levels continue to remain very low for NE Iowa. Continue to scout both corn and soybeans for foliar diseases.”

Southwest and West Central Iowa
Mike Witt (Region 6): “West central Iowa received some rain between 0.25 of an inch to 1.25 inches last week. This rain pattern has helped the crops continue to grow well with adequate moisture in most of the region. The cooler temperatures expected during the end of the week will help slow down some of the pollination and growth rate of the plants. Corn is anywhere from having pockets of tassels still emerging on later planted varieties to pollination complete and blister kernels starting to form. This spread is normal and with the forecast, the weather will be a good environment to finish the corn pollination season. Soybean fields are mostly closed canopy and are at the R2 growth stage. Fungicide spraying is in full swing across the area with many airplanes flying. Remember to scout your fields and make good economic decisions because disease has been very spotty so far in western Iowa with not all fields needing a fungicide. Insect populations are also spotty with Japanese beetles, grasshoppers, and corn rootworm beetles being reported. As a tip, there is usually more insect damage, especially from Japanese beetles, at the field edges as opposed to the middle. Be sure you hit your damage thresholds before spraying with tight margins this year. When soybeans are in the reproductive stage, the threshold for spraying for insect defoliation is if there is 20% defoliation across the whole field. Herbicide applications pretty much wrapped up last week, so if scouting for dicamba damage remember it occurs 10-14 up to 21 days after application.”

Soybean defoliation injury is often over-estimated. These leaves show various levels of soybean defoliation. Source: University of Nebraska Extension.

Central, East Central Iowa, Southeast, and South Central:
Rebecca Vittetoe (Region 8): “Corn is mainly in the R2 (blister) to R3 (milk) stage and soybeans range from R2 (full bloom) to R4 (full pod). Overall, crops look pretty good, but I was seeing some corn fields in the drier areas that were really starting to show signs of stress towards the end of last week. Gray leaf spot seems to be the biggest issue in corn right now. In some fields, the gray leaf spot is moving up in the canopy and fields are needing to be sprayed. If you haven’t recently checked your fields, I encourage you to do some scouting. Not seeing much for disease pressure in soybeans. On the insect side, potato leafhoppers continue to be a concern in alfalfa, and I also had a report of some armyworms in an alfalfa/grass hayfield. Other insects to be looking for include adult corn rootworms and first generation bean leaf beetles. On the weed side, I am seeing weed escapes appearing in fields. Now is a great time to walk fields and take care of some of those escapes, but also consider what caused those weeds to escape. Calls on off-target dicamba movement have picked up more in the last week.”

Virgil Schmitt (Region 9): “Rainfall amounts were generally less than 1.5 inch during the last week. Corn is mostly at R2 to R3 and generally looks good. Gray leaf spot took off last week in some fields and planes and helicopters started spraying in earnest. Soybeans are mostly R3 (begin pod) and also looks good. There is some Septoria brown spot in the mid canopy in some soybean fields. Off-target dicamba movement concerns and Japanese beetles dominated calls last week.”

Josh Michel (Region 11): “Some much needed precipitation provided some relief across the region, but rainfall amounts were spotty and varied from 0.1 inch to 1.5 plus inches in isolated areas. Pastures and hayfields are slowing down and showing more stress with the persistent dry conditions. Over the last week, oat harvest has wrapped up. Most corn fields are at R2 (blister), with a few fields at R3 (milk). Considering the lack of moisture, in general corn fields in the region are looking ok, but some fields are showing more signs of stress. Soybeans are mostly at R2 (full bloom) to R3 (begin pod), with some of the earlier planted fields at R4 (full pod), and in general they are looking good. Calls last week consisted of pasture management questions, late season weed management concerns, minor defoliation in soybeans, gray leaf spot, corn earworms, and group 4 herbicide damage in soybeans. Looking ahead, keep an eye open for spider mites, especially if the dry conditions persist.”

Corn earworms found feeding on the tip of some field corn in Appanoose County. Photo by Josh Michel. 

Check out the map below to find your local ISU Extension and Outreach field agronomist and find their contact information here!

Map showing the regions and counties field agronomists cover.

Category: Crop ProductionTags: field agronomistscrop updateAuthor: Rebecca Vittetoe

Rock and roll ain’t noise pollution to soybean aphid

Tue, 07/17/2018 - 08:06

Humans are making more sound, and it can interfere with animals finding mates, food and other essential behaviors. Most of the research showing impacts of human-generated sound is largely focused on vertebrates. Biologists at Mississippi State University were curious about sound potentially impacting insects – the largest group of animals on earth. They specifically looked at a tritrophic system: soybean, soybean aphid and predatory lady beetles.

Brandon Barton and colleagues wondered if noise pollution could change the growth rate of plants, soybean aphids and a predatory lady beetle. They coined the term “AC/DC hypothesis” and generated a hypothesis that “rock and roll ain’t noise pollution.” Music was used as a proof-of-concept in this predatory-prey interactions.

They had a lot of treatments, including playing AC/DC in growth chambers at 100 decibels for 14 days. I can’t imagine getting anything else done in the lab those weeks! In the end, the plants and soybean aphids were not affected by the loud music, but the lady beetles were less effective predators. Rock music altered the predation and ultimately those treatments had more aphids compared to treatments with no rock. What the lyrics, vibration or constant repetition of noise pollution? More research is needed to understand changes in behavior.

“Rock and Roll Ain’t Noise Pollution” is the tenth and final track of the 7th studio album, Back in Black. This Australian rock band.

Matt O’Neal and I dedicated part of our podcast to this research (it starts around 14 minutes). Read the original research paper here!

Category: Insects and MitesTags: soybean aphidpestpredatorslady beetlesAuthor: Erin HodgsonCrop(s): Soybean

Regional Crop Update July 2 to July 10, 2018

Tue, 07/10/2018 - 11:12

The warm conditions continue to push crops along. Across the state we are approximately 140 to 370 Growing Degree Days (GDD’s) head of normal. Most corn and soybean fields are now in the reproductive stages. Excessive moisture, drought, gray leaf spot, Japanese beetles, and off-target herbicide movement seem to be common issues Iowa State University Extension and Outreach field agronomists are seeing across the state this past week. Read on for more information about your region’s crop progress and field conditions.

Northwest Iowa   
Joel DeJong (Region 1): “Rainfall this past week was from half an inch to over 2 inches. That’s down significantly from recent weeks, thankfully. Many corn acres look great, particularly south of HWY 10. Corn is tasseling, although not quite half is at that stage yet. In the northern areas of this region, there remain lots of wet areas that have been lost and many blooming soybean fields that still need herbicide applications. Soybeans in the wet area have been struggling, but recent dry days have helped. Some green snap occurred in storms that rolled through on July 4. Corn rootworm beetles have just started to emerge, and a few bean leaf beetles are emerging, too. There have been a few phone calls and field visits due to dicamba injury in the region.”

Rainfall totals for the past week (July 2 to July 9) across the state of Iowa. Source: http://www.weather.gov. 

Northeast Iowa
Terry Basol (Region 4): “Considering the ample amount of rainfall over the past couple of weeks in Northeast Iowa, corn and soybeans are holding their own. According to the Iowa Mesonet, we received about 4.3 inches of rain from June 24 through July 8 at the NE Iowa Research and Demonstration Farm near Nashua. Most of the corn in the southern two-thirds of my territory has reached the R1 (silking) stage, with the rest of the corn throughout the territory in the mid to late vegetative stages (depending on planting date). I have seen some Physoderma brown spot showing up in corn fields last week due to favorable weather conditions. Green snap in corn fields has also been observed, particularly since the storm event on June 30th, which produced up to 50 – 60 mph winds across much of my territory. Soybeans are generally in the R1 (open flower at any node on the main stem) to R2 (open flower at one of the two uppermost nodes with a fully developed leaf) growth stage throughout my territory. Septoria brown spot remains to be found in the lower canopy; continue to scout and monitor to determine if it moves into the mid-canopy. There have been some reports of Phytophthora root and stem rot in soybean in the North Central and Northeast parts of the state due to the excessive rainfall and prolonged periods of saturated soils. So far, soybean aphid levels remain low from the weekly counts that ISU field agronomist Brian Lang conducts during the growing season.  

Southwest and West Central Iowa
Mike Witt (Region 6): “West Central Iowa received a break from the rain this last week with in general zero to 1 inch of rain falling on July 4. Corn is progressing well with fields anywhere from tasseling to brown silks. The current weather conditions with the warm nights are very favorable for quality pollination of corn. Soybean fields are greening up and canopies are starting to close. Final herbicide sprayings should be getting completed with soybeans, if not done, due to growth stages being mostly in R2 or full bloom. Diseases in corn are few with a little gray leaf spot and some Physoderma brown spot reported. So far this gray leaf spot is staying below the ear leaf and not progressing higher in the canopy so it is of lesser concern. Aerial fungicide applications are occurring around the area so be aware of surroundings and low flying planes. Japanese beetles are still the only insect flushes being reported with scattered small reports of bean leaf beetle or corn rootworm beetles seen. Remember, dicamba damage symptoms to crops occurs 10 to 14 and sometimes up to 21 days after application.”

Physoderma brown spot lesions on the midrib of a corn leaf. ​​Source: Farmers Guide to Corn disease IPM 76. 

Central, East Central Iowa, Southeast, and South Central:
Meaghan Anderson (Region 7): “The last week brought a welcome break from most of the rain in central Iowa, which has hopefully allowed some of the flooding to recede across fields and let the crops dry their 'feet' (roots) off a little. I've been told that with the break from rain, many of the soybean fields previously showing yellow patches have begun to green back up and look much healthier. Soybean rows have closed or are nearly there for being closed. Most corn and soybeans are now in reproductive stages, and the cooler weather at the end of last week was a welcome change for both me and surely the crops as well. Most corn looks to be pollinating beautifully across the area, but I have noticed some unevenness across fields persisting from earlier in the season. While we've been keeping a close eye out for advancing diseases, gray leaf spot is not as bad as I would have expected given the weather we've had. It's important to monitor fields and determine whether it is moving up in the canopy to the ear leaf and above. Some Japanese beetles have been noted eating silks, primarily along field edges, but I have yet to see a field that meets threshold. Now through the end of the growing season is a great time to monitor for weed escapes, manage the ones you can, and take good notes for this fall and next spring. Phone calls across Central and East Central Iowa continue to be on herbicide drift and yellow or nutrient deficient crops.”

Rebecca Vittetoe (Region 8): “The dry spells continues in this part of the state. The majority of corn and soybeans are now in the reproductive stages. A lot of the corn has already pollinated or is pollinating right now. As far as any issues go, I’ve been seeing some gray leaf spot in corn, but for the most part it seems to be staying in the lower canopy. Continue to monitor fields to see if moves up in the canopy to help determine if a fungicide application is warranted. I’ve also seen some minor defoliation in soybeans due a variety of pests including grasshoppers, Japanese beetles, and even some green cloverworm. On the forage side, we have definitely hit that summer slump and the dry conditions are not helping. Continue to check alfalfa fields for potato leafhoppers.”

Checking on pollination in a corn field. Silks still attached indicate that those ovules have not yet pollinated. Photo by Rebecca Vittetoe. 

Virgil Schmitt (Region 9): “Most of the territory I cover received no rain during the last seven days. The far southeast corner received between 0.5 and 1.5 inch and the northern most area received 0.25 of an inch or less. Corn is mostly V17 to R1 and generally looks good. There is a little gray leaf spot showing up in corn fields. Soybeans are mostly at R2 and also generally look good. Japanese beetles and malformed soybean leaves dominated calls last week.”

Josh Michel (Region 11): “The dry spell continues in this part of the state. While the dry conditions have allowed for farmers to make their second crop of hay and also start to combine oats and rye, unfortunately the dry conditions are really taking a toll on pastures and forage crops. Pastures and forage crops that were previously looking ok, are showing more signs of drought stress. Overall, corn and soybean fields are looking very good considering the limited amount of rainfall that we’ve received.  Soybeans are mostly R2 to R3 and corn is mostly R1 to R2.​​ Minor Japanese  beetle feeding and other insect defoliation have been observed in soybeans. Gray leaf spot and Physoderma brown spot can be found in corn fields, but so far these diseases are not progressing too quickly. If the dry conditions continue to persist, spider mites will be a pest to be keep your eyes open for in soybean and corn fields. Also, conintue to scout for potato leafhoppers in alfalfa. Calls last week mainly consisted of pasture management questions and herbicide group 4 or plant growth regulator off-target movement.”

Some minor skeletonization or defoliation of soybean leaves caused by Japanese beetles. Photo by Rebecca Vittetoe. 

Check out the map below to find your local ISU Extension and Outreach field agronomist and find their contact information here!

Map showing the regions and counties field agronomists cover. 


Category: Crop ProductionTags: crop updatefield agronomistscrop progressAuthor: Rebecca Vittetoe

Herbicide drift in 2018: How are we doing?

Mon, 07/09/2018 - 09:35

Off-target injury associated with dicamba application in dicamba-resistant soybean was a significant problem in the Cornbelt during 2017 (A final report on dicamba-injured soybean acres).  The increase in off-target problems associated with dicamba led to a record number of pesticide misuse investigations by the Iowa Department of Agriculture (IDALS) in 2017.  

So how do things look at this point of the growing season in terms of herbicide drift?  IDALS recently released data on pesticide misuse investigations for 2018.  While these investigations involve a wide range of ‘misuses’, the majority of complaints are due to herbicide drift.  As of July 2 there have been 137 investigations; 121 were associated with agricultural uses of pesticides.  At this time in 2017 there were only 82 complaints associated with ag applications, thus there has been nearly a 50% increase in pesticide misuse investigations compared to 2017.  However, timing of problems vary from year to year, so it is impossible to know how 2018 will compare to previous years in terms of total complaints. 

Fifty-nine of the investigations involved a growth regulator herbicide (approximately 40% of the ag complaints involved these products).  Dicamba and 2,4-D are the most widely used growth regulator herbicides in Iowa, but several other related compounds are used, including clopyralid, triclopyr, picloram, and aminopyralid.  There have been 17 investigations involving over-the-top (OTT) applications of dicamba (includes both corn and soybean uses).  We have heard about more cases of dicamba drift from use in corn this year than in the past.  It is too early to evaluate how successful the label changes and required training have been at reducing dicamba off-target movement from use in soybean.  In 2017, the majority of dicamba complaints in North Central Iowa came after July 4.  Calls to ISU Extension agronomists regarding off-target dicamba injury increased last week, so we should have a better understanding of the magnitude of problems within the next two weeks.

The significant increase in pesticide misuse cases during the first part of the growing season indicates a pesticide stewardship problem.  The wet weather in many areas of the state undoubtedly restricted available hours to complete field spraying; however, falling behind does not make it acceptable to apply pesticides during inappropriate conditions.  Agriculture must to a better job at managing pesticide applications to prevent further restrictions on how these valuable crop protection tools are used.

Category: WeedsTags: herbicide driftdicambadriftAuthor: Bob Hartzler

Regional Crop Update June 25 to July 2

Tue, 07/03/2018 - 16:46

Strong storms rolled across the state again bringing more heavy rain and even some damaging wind to areas. Despite the flooding in some areas and drought in the southern part of the state, 78% of the corn crop and 76% of the soybean crop was rated in the good to excellent condition based on Monday’s USDA Crop Progress Report. Iowa State University Extension and Outreach field agronomists share what they are seeing in fields across the state.  

Northwest Iowa 

Paul Kassel: “Herbicide application for the soybean crop will be the main activity this week in NW and NC Iowa. Dicamba applications on the soybean crop will be challenged this year as weed size has exceeded label requirements. Off-target movement may be an issue as well due to the windy conditions that have replaced the rainy conditions of last week. Some farmers are also considering aerial application of urea to add some nitrogen to a corn crop that is showing signs of nitrogen loss. Areas of fields that have stunted corn due to the waterlogged conditions may not respond to additional nitrogen. However, corn fields with nitrogen deficiency symptoms in better drained areas of the field may respond to additional nitrogen.”

This flooded corn field in Dickinson County is typical of many corn fields in my area. Photo by Paul Kassel.

North Central Iowa

Angie Rieck-Hinz: “Corn is V8 (northern Iowa) to R1 in Story/Boone Counties. There are still a lot of ponds, and heavy rains in places on Friday have left more crop fields with standing water to fields that are almost completely submerged.  Where there isn’t standing water, the corn crop looks good. I have seen some gray leaf spot, but all very minor at this point in time. There is still nitrogen being applied in some places and even urea being flown on where it continues to be too wet to get into the field. I have not seen any Physoderma brown spot, but there have been several reports of bacterial leaf streak in corn in NC Iowa. Soybeans are mostly R2, but there are some fields at R3. There were even soybeans just recently planted where pea harvest has been completed. In areas that continue to receive rainfall even, if the beans were not submerged or had ponded water, they are short, yellow and appear to be “going backwards”. Phytophthora root and stem rot is evident. The combination of small beans and lack of canopy closure along with delayed herbicide applications is causing some increased weed pressure in soybean fields.”

Septoria brown spot is starting to show up lower in the canopy in soybean fields. Photo by Angie Rieck-Hinz. 

Central Iowa

Meaghan Anderson: “It seems like some parts of central Iowa cannot catch a break from the wind, rain, and even hail this year. The Saturday night storms through parts of Dallas, Polk, Jasper, and other counties have caused some significant flooding in areas that may have season-long implications. Steve Johnson, farm management specialist for central Iowa, wrote a nice post on steps to take following these flood/wind/hail events. Aside from those issues, much of the corn is starting to tassel and pollinate, and really looks good overall. Soybeans look a little tougher in some areas with soggy roots, yellow plants, and some weed pressure and volunteer corn. Keep an eye out for insects feeding on corn silks and soybean leaves, as well as gray leaf spot showing up in corn fields."

The heavy rains that feel in Central Iowa put many fields underwater. Photo by Meaghan Anderson. 

Southwest and West Central Iowa

Mike Witt: “Crops in WC Iowa generally look good across the area minus some places that have drowned out due to previous flooding events. Last week’s rains were sporadic with totals in some areas of .25 inches to 3 inches in others. There were a few storms that caused damage around the I-80 corridor with some greensnap and root lodging reported. Corn is in the late vegetative stages with most fields already starting to tassel or will within the next week as they are only a few leaves back depending on planting date and maturity. Soybeans are in the R1-R2 stages, meaning blooming flowers are abundant and reproduction is occurring. Soybean fields look more patchy and ragged than corn with a lot of volunteer corn still needing to be removed. For diseases, there have been a few reports of very small amounts of gray leaf spot disease on the lower canopy of corn plants and some Septoria brown spot in the lower canopy of soybeans. Insects have not been a huge problem yet this season but farmers should remain vigilant in scouting. Post herbicide applications are continuing to occur with a few reports of dicamba damage and other issues coming in from the area.”

Southeast and East Central Iowa:

Rebecca Vittetoe: "Overall, crops continue to look really good in this part of the state. We've been fortunate to not be getting too much rain like some parts of Iowa. Some isolated areas did have some wind and green snap damage from last Thursday's storm. Most corn is tassel high by this 4th of July, with some fields already starting to pollinate. Most soybeans are in the R2 to R3 growth stage. With the warm and humid weather, we are starting to see some gray leaf spot show up lower in the corn canopy as well as some Physoderma brown spot. Common calls and questions over the past week include weed control issues, cupped soybeans, potato leaf hoppers, and gray leaf spot in corn." 

Cupped soybean leaves due to off-target movement from a plant growth regulator herbicide. Photo by Rebecca Vittetoe. 

Josh Michel: “Some well-timed rains fell across much of the area last week, ranging from half an inch up to two or three inches in some parts of SC Iowa. Based on the most recent  U.S. Drought Monitor map that was released on June 28, most of the area is considered abnormally dry to being in a severe drought. Alfalfa fields and pastures are hanging on, but most ponds are pretty low. Overall, corn and soybean fields are looking very good. Isolated areas did see some minor lodging and green snap from the storm that rolled through last Thursday. Most corn fields have tassels poking out, and there are many fields already at R1. Soybeans are at R2 with some fields at R3. Issues and calls from this past week include herbicide drift, late season weed control challenges, potato leaf hoppers, Japanese beetles, and corn flea beetles. Recent rains have provided favorable conditions for gray leaf spot and Physoderma brown spot to start to appear in some fields.”  

Corn flea beetle feeding on corn leaves from a field in Davis County. Photo by Cecil Reed. 

Virgil Schmitt: “During the last week, rainfall varied from less than 0.5 inch (mostly south of Highway 30 and near the Mississippi River) to over two inches in northern Jackson County. Corn is V14 to R1 and generally looking good. There is some gray leaf spot if you look in the right place. Soybean are R2 and also looking good. Calls have centered on weed ID and management, Group 4 herbicide drift, S & K deficiency symptoms, flooding impact on crops, and Japanese beetles. Grasshopper nymphs are hopping around and katydids are singing.”

Rainfall totals as of July 2 across the state of Iowa for the past week. Source: http://www.weather.gov. 

Check out this map to find your local ISU Extension and Outreach field agronomist here!

Category: Crop ProductionTags: crop updategray leaf spotphysoderma brown spotAuthor: Rebecca Vittetoe

Regional Crop Update June 18 to June 26, 2018

Tue, 06/26/2018 - 18:43

The saga continues with areas of northern Iowa receiving too much rain while southern Iowa continues to be on the drier side. Rainfall totals across the state ranged anywhere from nearly 10 inches in NW Iowa to less than half an inch in parts of southern Iowa. According to Monday’s USDA Crop Progress Report, 81% of Iowa’s corn crop and 79% of Iowa’s soybean crop is rated in the good to excellent condition. Check out what Iowa State University Extension and Outreach field agronomists are seeing in fields in NW, WC, EC, SE, and SC Iowa.   

Rainfall totals across the state of Iowa as of June 25th for the past week. Source: http://www.weather.gov. 

Northwest Iowa

Paul Kassel “Heavy rains were the main topic of discussion last week. Almost all of my area received between 4 to 5 inches of rain since June 20.  Most of that rain fell in areas that were already saturated. The exception is the southwest corner of Buena Vista County where rainfall amounts have been almost ideal this spring. Field work continues to be at a standstill. Weed control in the soybean crop will be a compromise since weed size has been exceeded for almost all postemergence herbicides. The good news is that the preemergence applications have worked very well. Corn development looks good in the well-drained fields. There is some corn that was planted on April 30 that is at the V12 stage, is 4 feet tall and is predicted to start tasseling on July 6.”

This Clay County soybean field is showing stress from water logged conditions. Photo by Paul Kassel. 

Southwest and West Central Iowa

Mike Witt “This week in West Central Iowa rain is the name of the game. Flooding issues will impact yields this year, but it is too early in the process to make a good assessment. Corn generally is looking good and is in the late vegetative stages with a few tassels showing in the area. Soybeans are mostly in the R1 and R2 stages which means blooming is occurring. Nutrient issues such as Nitrogen deficiency or general yellowing from water will show up with the rain patterns and wet areas in the fields. Japanese beetles are starting to show up in fields in west central Iowa so be aware of them and damage they can cause. Overall crops are handling the rain and flooding issues the best they can. Once things dry out a bit there will be more evaluations to do as far as weeds, nutrients and blank field hole filling in.”

Southeast and East Central Iowa:

Meaghan Anderson: “Corn is in late vegetative stages and looking beautiful across most of east central Iowa. Many fields will likely begin to shoot tassels this week, and agronomists will be keeping an eye out for diseases like gray leaf spot. Given the recent rainfalls, Physoderma brown spot may be showing up in corn as well. Soybeans are flowering across much of the area, with many fields already at R2.  Phone calls in the last week have continued to include potassium deficient corn and herbicide issues in both corn and soybean. Dicamba injury phone calls in soybeans have started and will likely continue over the next several weeks.”

A good reminder to pay close attention to what traits are planted where and where what herbicides get sprayed. Here is some glyphosate tolerant corn that was accidently sprayed with Liberty or glufosinate instead. Photo by Meaghan Anderson. 

Herbicide group 15 injury in a soybean field that was mistaken for dicamba injury. Photo by Meaghan Anderson. 

A known infested field of Palmer amaranth in EC Iowa. This is a good reminder that when out scouting to double check any suspicious looking plants. Here's a handy resource for identifying Palmer amaranth. Photo by Meaghan Anderson.  

Rebecca Vittetoe and Josh Michel: “Based on the U.S. Drought Monitor much of SC Iowa is considered to be in either a moderate or a severe drought. Thankfully, some much needed rains fell last week and over the weekend, with rainfall totals ranging from half an inch to over two inches of rainfall. Alfalfa fields and pastures are looking good with the recent rains, but many ponds are still low. The warmer summer temperatures are slowing forage growth, which we often call the summer slump. Overall, corn and soybean fields are looking very good.  Most corn fields are at least V14, with some fields already starting to show some tassels. Soybean fields are pretty much all in the reproductive stage, being either at R1 or R2. Common issues seen this past week include potassium deficiency, herbicide issues, weed control challenges, potato leaf hoppers, and Japanese beetles. With the recent rains, gray leaf spot is also starting to show up on the lower leaves in some corn fields. Take some time to scout fields this week and see how your post herbicide application is working and check for any potential disease or insect issues.”  

Warm and humid weather provides favorable conditions for gray leaf spot to develop. This gray leaf spot lesion was found lower in the canopy in a corn field in Washington County. Photo by Rebecca Vittetoe. 

Virgil Schmitt: “Over the last week, most of my territory received 2 – 3 inches of rain, with some spots receiving 5+ inches and some spots between 1 and 2 inches. Corn is mostly V12 plus or minus a leaf and is generally looking good. Soybean are mostly R2 and also looking good. Dicamba drift, potassium deficiency symptoms, sulfur deficiency symptoms, glyphosate resistant waterhemp, Japanese beetles, poor soybean emergence, herbicide carryover, and spray equipment contamination dominated calls last week.”

Check out this map to find your local ISU Extension and Outreach field agronomist here!

Category: Crop ProductionTags: field agronomistscrop updatefloodingjapanese beetlesAuthor: Rebecca Vittetoe

Regional Crop Update June 11 to June 19 2018

Tue, 06/19/2018 - 12:07

Parts of Iowa received some much needed rainfall last week, but unfortunately for some areas the storms that rolled through also brought along hail and caused flooding. Overall, crops are looking good across the state with 84% of the Iowa corn crop and 80% of the soybeans crop being rated in the good to excellent condition based on Monday’s USDA Crop Progress Report. Iowa State University Extension and Outreach field agronomists report crop conditions in their respected regions.  

Northwest Iowa

Joel DeJong (Region 1): “The NW Corner of Iowa had a mixed week – some areas received almost no rainfall, and areas of O’Brien and Osceola County had many reports over 6” of rain. Localized flooding occurred due to that rainfall event. Areas that did not receive rain last week have already had a good rain early this week. For the most part, crops are looking very good, and the U2U growing degree model shows predicted silking for many fields before the middle of July – and some in early July. Soybeans at the NW Research have begun to bloom in the 4/30 and 5/7 planting date plots. There remain some yellow streaks in a few cornfields, some carry-over herbicide issues, and a few cases of herbicide drift. Watch weather conditions and understand the label before all herbicide applications!”

Soybeans planted on 4/30 and 5/7 are blooming at the NW IA Research Farm. Photo by Joel DeJong. 

Paul Kassel (Region 2): “Field work progress has come to an abrupt halt for much of my area. Recent rains have been excessive in parts of Pocahontas, Clay, Palo Alto, Dickinson and Emmet Counties. In contrast, there are areas in Sac and Buena Vista Counties that are dry – and have received only a couple of inches of rain in June. There are some corn fields that will not get their postemergence herbicide application – due to the recent windy weather, rainy weather, excessive rain, etc. There is also concern of the timeliness of the postemergence herbicide for the soybean crop. The pre-emergence products are working quite well.  However, it may be a challenge to be timely with fomesafen (10-month corn rotation restriction) and dicamba (weed size and potential for off target movement).”

Corn crop showing injury from a 2017 misapplication of fomesafen in Pocahontas County. Note that even the replanted corn is also showing injury symptoms. Photo by Paul Kassel. 

Northeast Iowa

Terry Basol (Region 4): “Corn and soybeans continue to develop rapidly in NE Iowa, given the warm temperatures and current soil moisture conditions for the past week. Corn is anywhere from V5 up to V8 – V9 and we are still seeing some fields that are showing signs of rapid-growth syndrome (pictured above). For more information on rapid growth syndrome, see the ICM article titled: Twisted whorls, buggy whipping, yellow leaves. In general, soybeans are anywhere from V3 up to R1 for most of NE Iowa, with postemerge herbicide applications occurring throughout the area within the last week. Oats in NE Iowa are 46 percent headed out according to the most recent Iowa Crop Progress & Condition report by the National Agricultural Statistics Service (NASS). Eighty-three percent of the oat crop statewide was rated in good to excellent condition.”

Corn field with plants showing symptoms of rapid growth syndrome in NE Iowa. Photo by Terry Basol. 

North Central Iowa

Angie Rieck-Hinz (Region 3): “The week of June 11 saw spotty to heavy rain across central to NC Iowa. Rainfall reports indicated amounts of 0.5 to 6 plus inches. While some areas received too much rain, the eastern most part of Story County, parts of Hardin and Marshall could use some rain. In areas with excessive rain, we have a lot of ponding and loss of crop in potholes and other places where the rain was so intense we experienced severe erosion washing out areas in fields. There are still areas in the northern regions that were planting soybeans last week. I have received several phone calls on herbicide carryover from 2017 as well as herbicide injury from tank contamination. On Friday (June 15) I looked at an armyworm infestation in a soybean field that had a cereal rye cover crop. The armyworms were not eating the soybeans, but were defoliating the bromegrass in the ditch and moving into the corn. This should be a reminder to anyone who had a cereal rye cover crop to scout for armyworms, not only in the soybean field but also adjacent corn fields. Armyworm will eat soybean, but prefer grass.” 

Southwest and West Central Iowa

Aaron Saeugling (Region 9):  “Corn is looking good as isolated showers have helped keep the corn growing. Herbicide applications and sidedressing nitrogen has basically wrapped up in corn. Currently, not seeing any major insect issues as of right now. Unfortunately, some areas experienced hail damage, but most of the corn is growing out of the damage. Heat and lack of rainfall will be the challenge in the coming weeks. While the corn is looking good, the soybeans have struggled a little bit more. We have had several issues this spring with soybean emergence due to herbicide issues, planting depth, diseases, and insect pressure. The focus this week in soybeans will be post emerge herbicide applications. My recommendation for farmers is to scout, scout and scout. Hay and pasture conditions are holding on right now. If you feel pasture may be short in the coming month either rotate pastures or supplement cows now to avoid overgrazing. A little supplement now will pay big dividends this fall for grazing and regrowth of pastures.”

Southeast and East Central Iowa:

Rebecca Vittetoe (Region 10) and Josh Michel (Region 11): “We received some much needed rainfall in parts of SC Iowa, which really helped the crops through the heat this past weekend. Rainfall ranged from three or four tenths to a couple of inches in areas. Corn is mostly in the V10 to V12 stages and soybeans are mostly V3 to V5 stages, with many fields already flowering (R1). Common issues, calls, and field visits last week included yellow and uneven corn, potassium deficiency showing up in corn, herbicide issues, and weed control challenges. It was not uncommon, especially on the really warm days, to see corn leaves rolling. Potato leaf hoppers were found at the ISU McNay Farm near Chariton in the alfalfa plots, so that is a good reminder to get out and scout for potato leaf hoppers. Another insect pest to keep an eye out for is Japanese Beetles as they have started to emerge. Just be careful not to be them confused with chafers, another beetle that at first glance is often mistaken for Japanese Beetles. Pastures and hay fields are hanging in there, but pond levels are really showing how dry we are in SC Iowa.”  

(Left photo)Take the time to scout your alfalfa fields for Potato Leafhoppers. (Right photo) Corn plants in a field just south of Centerville, IA on 6/15/18 showing signs of potassium deficiency and leaf rolling due to the dry conditions in this part of the state. Photos by: Rebecca Vittetoe. 

Virgil Schmitt (Region 8): “During the last week, in the counties I cover, areas roughly east of HWY I-380, HWY 281, and HWY 27 received less than 0.5 inch of rain while areas roughly west of that line received between 0.5 and 1.0 inch of rain. Oats are heading out. Corn is mostly V10 plus or minus one leaf, and it is generally in good condition. However, the corn has been showing signs of moisture stress during the hottest portions of the day. Soybeans are mostly V3 plus or minus a leaf. A few fields are at R1 and there are even some fields at R2. Soybean fields generally look good. Calls started last week on herbicide group 4 injury symptoms on soybeans as well as calls regarding waterhemp management.”

Rainfall totals across the state of Iowa for the past 7 days. Source: http://www.weather.gov.

Find your local ISU Extension and Outreach field agronomist here!

Category: Crop ProductionTags: field agronomistscrop updatefloodinghaildry conditionsAuthor: Rebecca Vittetoe

Integrated Pest Management program now available on Facebook

Mon, 06/18/2018 - 15:27

The Iowa State University Integrated Pest Management (IPM) program is expanding its social media footprint to now include Facebook. If you follow our content on Twitter (@ISU_IPM) then be sure to give our page a like to stay connected.

Through Facebook, the IPM program hopes to reach a wider audience wherever they might source their information, to promote responsible land stewardship while promoting stable and high yields for farmers, as well as the responsible in-home management of household pests and plant diseases. We'll work to share and promote the information done by our partners, collaborators and researchers on Facebook in the form of articles, videos, surveys and community groups to continue the discussion of integrated pest management.

To quickly find our account, go to facebook.com/ISUIPM, and click on the "like" button.

Be sure to check back in for more updates coming to the IPM program!

Category: Insects and MitesPesticide EducationPlant DiseasesTags: integrated pest managementcrop scoutingInsectsdiseasesAuthor: Ethan Stoetzer

Flooding and Hail, Oh My!

Fri, 06/15/2018 - 08:03

Yesterday’s heavy rains that marched across large part of central and north central Iowa coupled with recent storm systems across other parts of the state have resulted in significant areas of ponding as well as hail injury.

Flooded fields will take several days for the water to recede to fully evaluate how much crop areas was destroyed. A may be able to survive under water for 1 to 4 days depending on the crop stage and air temperature. And even if the crop does survive, saturated soil conditions will undoubtedly stall root growth and hinder nutrient uptake and growth. At this stage of the growing season, it is unlikely that replanting drowned out areas will be a viable option. However, when the water recedes and field conditions are fit, it would be worthwhile to plant a cover crop to protect the soil and compete against weed growth. ICM News Corn Survival in Flooded or Saturated Fields has some additional information on survival of corn that has been under water.

Hail injury to the corn and soybean crop will be relatively minor in the earlier growth stages. Yield loss from hail to corn increases through vegetative growth and peaks at pollination before decreasing through grain fill. Whereas, soybean hail injury increases as the growing season progresses and peaks during the seed filling stages. At this time of the year, hail injury may only result in a 5-20% corn yield loss or 5-30% soybean yield loss. ISU Extension publications Hail on Corn and Hail on Soybean have additional information on management options and yield impacts from hail injury.

Flooded and hail injured demonstration plots at the Field Extension Education Laboratory on June 14, 2018.

Category: Crop ProductionTags: floodinghailcorn managementsoybean managementAuthor: Mark LichtCrop(s): CornSoybean