When steel grain bins sustain wind damage, careful inspection is needed to evaluate repair or replacement options. Inspection assistance and advice from a consulting engineer or bin manufacturer representative is the best option.
When damage is confined to the roof, sidewall sheets, or wall stiffeners of the bin, replacement of damaged materials may be feasible. Evaluation of displacement, distortion, or over-loading of the remaining structure is necessary prior to replacing damaged steel.
When damage spread to the foundation or anchor components, a thorough evaluation of the foundation will be necessary. Significant damage to the foundation may warrant complete reconstruction of the bin and foundation.
Replacement of only the bin itself must be compatible with the existing foundation design and anchoring system. Changing the diameter, height, or anchor locations of the replacement bin is likely not possible without thorough foundation design confirmation.
Grain handling equipment such as bucket elevators, downspouts, cross conveyors, and support structures should also be inspected for damage caused by the wind or by stresses from movement of attached bin parts.
Before making replacement decisions, consider the overall grain system design and suitability for current and future needs. While storm damage and repair is stressful and costly, it may present an opportunity for reconsidering and redesigning the entire system. Consult with an expert in grain system planning or materials on grain system layout and design from Midwest Plan Service, available online or through your county ISU Extension and Outreach office.
Contact your ISU Extension and Outreach Field Agricultural Engineer for additional advice.Category: Grain Handling and StorageTags: storm damagegrain bingrain bin damagegrain storageAuthors: Shawn ShouseDirk Maier
Monday’s derecho event took a toll on crops across Iowa. Satellite imagery shows millions of acres of Iowa crops impacted by the high wind events. As growers dig out from the destruction left after the storm, decisions regarding how to manage the impacted crop will be front and center.
For wind damaged corn, the decision about how to manage the crop will largely depend on if the plants are bent over or snapped off. Plants that are bent can still transport water and nutrients. These plants should continue to mature, although at a slower pace. Plants that are broken or snapped below the cob will result in plant death.
UAVs are an effective tool to help assess the magnitude of damage in a field and determine if stalks are leaning or snapped off. UAVs have become prevalent within agriculture networks in the past few years and many neighbors, ag retailers or crop consultants have access to UAVs that can help evaluate crop damage.
A Bird’s Eye View image can provide a quick look at the extent of crop damage in your field (Figure 1). Anywhere you can’t visually “row the corn” indicates areas of crop damage. You will also normally notice downed corn has a lighter color as the lower side of corn leaves and stalks will reflect light differently. While this view provides an effective early indicator, it does not allow you to calculate the total area of impacted crops.
Figure 1: A Bird’s Eye View of crop damage caused by high wind events. This view can define the general scale of the impacted crop in a field.
UAVs can also support a Close Up View of crop damage in parts of a field that would be difficult to scout given the conditions. This includes flying out to regions of a field not visible to get a better look at the magnitude of crop damage (Figure 2 and 3). Additionally, by adjusting the camera angle towards the base of the plants, the imagery can help determine the extent of green-snap present. These views are helpful both in making immediate decisions regarding crop health and in monitoring the crop health and dry down as the season progresses.
Figure 2: A Close Up View of crop damage caused by high wind events. In this example the corn is leaning but has not snapped off.
Figure 3: A Close Up View of crop damage caused by high wind events. In this example the corn is snapped below the ear which results in total plant death.
A Full Field Map can be created by stitching together several individual UAV images (Figure 4). Creating a Full Field Map will take more time and require the entire field to be flown in a pattern by the UAV. The primary advantage to this method is that you can use web tools to estimate the area of a field that is impacted. This will be helpful in the areas of Iowa along the edge of the derecho where only a portion of a field suffered crop damage.
Figure 4: A Full Field Map of crop damage caused by high wind events. This view allows for measuring the area of impacted crops and is helpful in assessing damage in a partially impacted field.Category: Crop ProductionTags: Digital Agcorn damageUAVsdronescrop scoutingAuthors: Matt DarrRyan W Bergman
While some rainfall has come to the droughty areas of the state, drought intensified to D3 (extreme) drought in parts of central and west central Iowa. Unfortunately, a large swath of the state is now facing devastating infrastructure and crop damage after the August 10 Midwest Derecho. Our thoughts are with all Iowans as they work to assess and recover from damage. Other issues noted by field agronomists prior to August 10 include fast maturing crops, twospotted spider mites, spotty foliar diseases, a general tapering off of some insect pests, and continued concerns about off-target dicamba movement. Read on for more specifics for what’s happening in different regions across the state.
Joel DeJong (Region 1): “In the NW corner of Iowa – received nice rainfall in the past week in about the southern half of the area I serve. The north half had a few tenths. We missed most of the severe wind damage, and feel for those who didn’t miss it. Lack of moisture remains an issue in much of the area, tip back very prominent, and it seems maturity of plants in the driest areas is speeding along quicker than I like to see. Spider mites are rather common, but soybean aphid numbers, although present in more fields, seem to be staying below thresholds in most fields. The waterhemp misses are becoming more visible in soybean fields, too."
Twospotted spider mites and eggs on a soybean leaf. Photo by Meaghan Anderson.
Paul Kassel (Region 2): “Corn and soybean crops continue to deal with dry soil conditions across much of the area. Parts of Sac county are now classified as D3/Extreme drought. Also, parts of Buena Vista, Pocahontas, Clay and Palo Alto are dealing with D2/severe drought. Some rainfall amounts of 0.5 to 1.0 inch have occurred in parts of Kossuth, Hancock and Winnebago counties recently. Crop development also appears to be progressing rapidly as corn approaches the dent stage. There are soybean fields that are approaching the full bean/R6 stage of development. The amount of time from R6 stage until R7/early maturity stage is around 20 days. Insect pest problems have been low so far. Farmers and applicators are encouraged to check soybean fields for soybean aphid development. Soybean aphid levels have been light so far. The risk of damage from soybean aphid is reduced once the soybean crop reaches the R6 stage."
Farm program discussion at the August 6 drought meeting in Sac County. Photo by Paul Kassel.
North Central Iowa
Angie Rieck-Hinz (Region 3): “Rains continue to be spotty, but nearly every reporting station across my 9 counties reported some rain during the week of August 3 through August 10. Rainfall ranged from 0.18 inches at Rockwell City to 1.13 inches at Fort Dodge. Eldora and Hampton continue to see only about 20 to 25% of their average rainfall for this time of year. Rainfall reports for the storm that pushed through on August 10 are so varied that I don’t think it will do much to alleviate our drought concerns in the more severely impacted areas. Corn is mostly R4-R5. There continues to be little disease pressure in the majority of fields. Soybeans are R5.5 to R6. I have seen some frogeye leaf spot, but at low levels. I was in Rockwell City when the August 10 storm hit. A crop tour after the storm with a local farmer and seed dealer showed there was leaning corn and tattered beans in scattered places. I tracked this on my way home with scattered crop damage in southern Webster and Hamilton counties. I live in northern Story county and once you get east of the interstate 35, there are numerous acres of flattened corn, tattered and lodged beans and missing grain bins, plus a lot of structural damage."
Droughty soybeans showing up on the isolated areas of Flagler sandy loam soil in Story County. Photo by Angie Rieck-Hinz.
Terry Basol (Region 4): “Just like most of the state, corn and soybeans in Northeast Iowa could use some precipitation, as all of the NE counties have entered into the category of DO (abnormally dry, according to the United States Drought Monitor). Most of the corn is finishing up the R3 stage (Milk) and has begun the R4 stage (dough). According to the National Agricultural Statistics Service (NASS), 77 and 59 percent of the corn as of August 9th in North Central and Northeast Iowa respectively, is in the dough stage of growth. The most common foliar disease so far this season that’s shown up in the last few weeks is gray leaf spot. There has been some isolated cases of tar spot reported and confirmed in the counties Floyd, Butler, Black Hawk, and Buchanan, but generally few and far between up to this point. Soybeans are finishing up the R4 stage and beginning the early stage of R5. This is the time period for soybeans where the seed is 3 mm (1/8 inches) long in the pod at one of the four uppermost nodes on the main stem with a fully developed trifoliolate leaf node. Japanese beetle feeding is now tapering off in most soybean fields, but continue to monitor defoliation levels, as grasshoppers are also feeding. In dry years, grasshoppers can become problematic as their normal vegetative food sources are decreased and they turn to feeding on soybeans. For more information on scouting and thresholds for pests that feed on soybeans, check out the ICM article titled “Scouting guidelines for soybean defoliators” here. As stated earlier, we could use a good drink from Mother Nature, as we have only received 1.07 inches of precipitation at the Northeast Iowa Research and Demonstration Farm since August 1st according to the Iowa Mesonet."
Meaghan Anderson (Region 7): “Most of central Iowa received anywhere from about 0.5" to more than 3 inches in the last week. This rain was needed, but droughty areas are still <50% of normal rainfall for the last 60 days, so most areas got a small drink compared to what is needed. Unfortunately, the most recent rainfall brought significant wind that impacted corn fields over nearly the entire region of the state that I serve. Corn fields that were in the R4 (dough) to early dent (R5) are now facing finishing out kernel fill with plants mostly on the ground and harvest will be especially arduous this fall. Bob Nielsen (Purdue University) wrote a nice article in 2018 outlining the effects of severe stresses during corn grain fill that is very useful. The prospects for recovery in these fields do not seem encouraging this late in the growing season. Additionally, the storm caused significant structural damage to livestock buildings, farm sheds, homes, and grain bins (to name a few). Weedy areas of soybean fields continue to become more apparent and I've received more phone calls recently with questions about survivors of 2,4-D and dicamba herbicide applications; resistance to these herbicides has been discovered in Palmer amaranth in other states but has not yet been officially reported in Iowa waterhemp populations. Speaking of Palmer amaranth, now is a great time to be scouting for it in Iowa. Insect issues in both corn and soybean are mostly tapering off. Common phone calls this week were about corn recovery from wind damage, weed identification, twospotted spider mites in soybeans, and Japanese beetles in corn and soybean."
Corn completely flattened in Boone County by the derecho on August 10. Photo by Meaghan Anderson.
East Central, Southeast, and South Central:
Virgil Schmitt (Region 9): “Rainfall last week in the counties I cover was generally less than 0.1 inch. In general, temperatures last week in the counties I cover and statewide were cooler than normal. Most corn fields are at R4 and generally looking good, except for storm damaged fields. Gray leaf spot lesions and occasional sightings of tar spot continue. Soybeans are mostly R5. In general, they also look good, again except storm damaged fields. Dicamba drift, potential dicamba resistance, late summer seedings, cover crops were common topics of discussion last week."
Check out the map below to find your local ISU Extension field agronomist and find their contact information here!
Category: Crop ProductionTags: CornSoybeandroughtstorm damagewind damagetwospotted spider mitescrop maturitycrop updateAuthors: Meaghan AndersonRebecca VittetoeCrop(s): CornSoybean
Drought conditions persist in western Iowa and have expanded further into central and north central Iowa this week. Common issues reported by ISU Extension field agronomists this past week included poor grain fill and fast reproductive development in corn, increasing disease pressure in some corn fields, concerns regarding off-target movement of dicamba, and a variety of insect issues including corn rootworms, potato leafhoppers, Japanese beetles, twospotted spider mites, and white flies. Read on for more specifics for what’s happening in different regions across the state.
Paul Kassel (Region 2): “Abnormally dry conditions, moderate drought and severe drought cover most of the area that I serve – according to the July 30 U.S. Drought monitor. The area of severe drought is mostly confined to Sac county. Crop conditions have deteriorated because of this lack of rainfall. Many areas in Sac, Clay, Buena Vista and Palo Alto county are showing large areas of moisture stressed crops in fields that have deep, productive soils. Crop development is progressing rapidly. It is common to see corn in the R4/dough stage – which is about a week ahead of schedule. This increase in the rate of crop development may signal a response to the dry weather. This is also likely an indication of reduced dry matter accumulation and reduced crop yields. Soybean aphids can be found in area fields, but they are at low levels. Farmers and agronomists are encouraged to keep checking fields for soybean aphids through the R6/full bean stage of soybean development.
Drought conditions reduce yield potential on this Clay county corn on corn field. Photo by Paul Kassel.
North Central Iowa
Angie Rieck-Hinz (Region 3): “Lack of precipitation is causing more area in NC Iowa to show up on the drought monitor. Generally speaking rains were very spotty the week of July 27 through August with Humboldt reporting 0.2 inches and all other locations reporting lesser amounts if any rain. Isolated showers on Saturday, August 1st produced up to 0.3 inches between Gowrie and Callender. Crop stress is starting to show up in Cerro Gordo and Worth counties as well. Most corn is at R4 or dough, but occasionally I have found fields starting to dent or at R5 so we are pushing maturity with the high temperatures and lack of precipitation to assist with grain fill. Soybeans are mostly R5 or beginning seed. There are a few reports of low-level soybean aphids. Both corn and soybean disease pressure remains low."
Meaghan Anderson (Region 7): “Most of central Iowa got some much-needed rain in the last week, though much of Dallas, Polk, Jasper, Madison, and Warren counties received <0.5 inch. Corn is mostly R4 in the area, though I've noticed a handful of kernels beginning to dent in some fields. In areas that have received more rainfall, corn looks mostly excellent but gray leaf spot pressure is increasing in some fields. Soybeans are primarily R4-early R5. Some waterhemp patches are beginning to show up in soybean fields. While most of my area is considered abnormally dry or in moderate drought, the most significantly affected area is western Boone County , western Dallas County and far NW Madison County. Soybeans are beginning to show significant moisture stress and corn ear development and grain fill are extremely variable. Twospotted spider mites are prevalent in many fields in these counties. Common phone calls this week were about off-target dicamba injury to soybeans, weed identification, fungicide application decisions, potato leafhoppers in alfalfa, and white flies in soybeans.
Twospotted spider mite injury along a soybean field edge in Dallas County. Photo by Meaghan Anderson.
Drought conditions caused significant tip back on ears in this Dallas County continuous corn field. Photo by Meaghan Anderson.
East Central, Southeast, and South Central:
Virgil Schmitt (Region 9): “Rainfall last week was generally less than 1.0 inch. In general, temperatures last week in the counties I cover and statewide were near normal. Most corn fields are at R3 – R4 and generally looking good, except for storm damaged fields. Gray leaf spot is increasing. Soybeans are mostly R3 – R4. In general, they also look good, again except storm damaged fields. White flies are abundant in some fields. Corn rootworm trait failure (continuous corn), Japanese beetles, white flies, dealing with storm damage to crops, fungicide and/or insecticide applications, and dicamba drift were common topics of discussion last week.
Josh Michel (Region 11): “Scattered showers provided some relief to parts of SC and SE Iowa, with areas receiving anywhere from 0.25 to 1 inch of rain over the past week. Corn is generally R2 to R4, with many fields still looking good, despite limited rainfall. Symptoms of heat stress are still occurring in areas with poor soils. Gray leaf spot continues to be found throughout the region, along with some minor reports of corn rootworm damage and southern rust. Soybeans are generally R3 to R5, and are also looking pretty good. The majority of my soybean field calls have centered around insect feeding and weed escapes, especially with soybeans planted on 30” rows. Alfalfa continues to grow very slowly, with many reports of moderate to severe insect feeding, mostly due to potato leafhoppers and grasshoppers. Forages in pastures have been growing very slowly as well. Recent cooler temperatures and small amounts of precipitation are expected to slightly improve crop conditions.”
Check out the map below to find your local ISU Extension field agronomist and find their contact information here!Category: Crop ProductionTags: crop updatefield agronomistsscoutingCornsoybeanspastureshaydroughtAuthors: Rebecca VittetoeMeaghan AndersonCrop(s): CornSoybeanBiomass and Forage
By: Madelynn Connell, Danielle M. Clark (Wilson), and Emily Heaton
In the interview, “A Farmer’s Journey with Miscanthus: Part 1,” we learned about Steve Schomberg and his involvement with growing miscanthus for the University of Iowa power plant. Steve has also been working with Koch Angus Farms, a cattle production farm near Letts, Iowa for the last four years. During this time, he got to know Scott Hintermiester, a herdsman for Koch Angus, who manages the day to day operations for the last two years. Steve donated some large round and small square miscanthus bales to test as bedding for their calves and cattle.
Figure 1. Freshly laid miscanthus bales.
Typically, hay is used to absorb cattle manure in barns. Scott used some bales of miscanthus instead of hay during fall 2019 into January 2020.
Figure 2. Miscanthus bales after 1 week of cattle use.
He reported that the miscanthus bales were very dry and absorbent and lasted twice as long as corn bales would in the same conditions. The miscanthus bales were easier to break apart than corn bales and were easily spread with a tractor. These two photos show the difference between freshly laid miscanthus (Figure 1) and the same area after the cows had used it for over a week (Figure 2).
Scott would like to move toward using only miscanthus at Koch Angus Farms and planting their own if economically feasible. The ISU Biomass lab focuses its research on identifying the economic and sustainable benefits of growing miscanthus. We believe miscanthus is a good alternative to traditional biomass crops, and could be widely used if it were more available to farmers.
Figure 3. Calving barn with miscanthus bedding.
Small miscanthus bales were also used in the calving barn (Figure 3). Calves require bedding to help keep them warm and dry during the winter. The absorbent properties of miscanthus make it an ideal choice for the calving barn. Scott does warn that it is somewhat dusty initially, but becomes less so as it is used and causes no harm to the farmers or calves.
He believes it would provide high quality bedding in open pig barns. Scott has hopes that more farmers will transition to using miscanthus bedding on their farms. His favorite part of his job is calving. He says, “I still get excited every time a cow has a calf; it never gets old!” We can see why
Photo credits: Scott Hintermiester
Product of ISU Biomass Undergrad TeamCategory: Crop ProductionTags: giant miscanthusAuthors: Danielle M Clark (Wilson)Emily HeatonCrop(s): Biomass and Forage
ISU Extension and Outreach field agronomists, Meaghan Anderson and Angie Rieck-Hinz, recently partnered with their extension colleagues at the University of Minnesota to organize and deliver the second webinar series, Essential Row Crop Management. This series featured four topics discussing mid-season crop management. The topics included Tar Spot identification and in-season management, Soybean Aphid IPM, Corn Rootworm Management and Soybean Gall Midge update.
These presentations have been recorded and are now available at the Essential Row Crop Management web page. Each webinar included a short discussion on the key topic followed by time for questions and answers. As peoples’ time is limited during a busy season, webinars were limited to about 30 minutes. Additional resources for each topic are available in a publicly accessible cloud storage venue called Cybox.
If you participated in the live webinars, or watch the recordings, we ask to please share your feedback via this survey. Your feedback helps us to improve delivery and identify future topics.
Thanks to the generous support of the Iowa Soybean Association, Iowa Corn Growers Association, Minnesota Soybean Research and Promotion Council and Minnesota Corn Growers Association, we were able to bring this program to you free of charge.Category: Crop ProductionInsects and MitesPlant DiseasesTags: tar spotsoybean aphidcorn rootwormsoybean gall midgeAuthors: Angie Rieck-HinzMeaghan AndersonCrop(s): CornSoybean
Over the last two weeks I have received a few calls related to identifying a “new form of waterhemp” in Southwest Iowa. In reality, we do not have a new form of waterhemp, but a condition referred to as ‘fasciation’ (Figure 1). While this can occur in many plant species, plants like cacti and members of the sunflower family (Asteraceae) are more likely to have fasciation of stem cells. However, we’ve noticed it quite commonly on waterhemp this year, so what’s going on?
Figure 1. Fasciation on a waterhemp plant. Photo courtesy of Aaron Saeugling.
Figure 2. Another example of a waterhemp plant showing what's known as fasciation. Photo courtesy of Meaghan Anderson.
Figure 3. An example of fasciation on a sunflower plant. Photo courtesy of Dr. Bob Hartzler.
What happened with these plants is that something goes wrong with the apical meristem when trying to divide and grow. Typically cells in plant stems divide and form cylindrical or round stems for most plants. It is believed that the fasciation is caused by mutation of a single cell in the central meristem and causes cells to increase dramatically causing the growing point to develop a new plant. You could say a plant growing in another plant, so to speak. What causes plant fasciation in nature is a mystery, but environment can play a key role. Mostly this is a hormonal response to some environmental stress on the plant, but other factors could be involved. Be on the lookout for Frankenstein weeds.
Klingaman, G. 2008. Plant of the Week: Fasciated Plants (Crested Plants). University of Arkansas. https://www.uaex.edu/yard-garden/resource-library/plant-week/fasciated-2-22-08.aspx (Accessed 28 July 2020).Category: WeedsTags: waterhempAuthor: Aaron Saeugling
While the drought concerns and drought impacts on row crops and forage crops seems to be the big issue especially in western Iowa, other common issues or questions reported by ISU Extension field agronomists this past week included corn rootworm activity, earworm feeding, Japanese beetles causing defoliation in soybeans and silk clipping in corn, low levels of soybean aphids, potato leafhopper damage, gray leaf spot pressure increasing (especially eastern Iowa), low levels of frogeye leaf spot, fungicide application decisions, and continued reports of dicamba injury. Read on for more specifics for what’s happening in different regions across the state.
Joel DeJong (Region 1): “Last week gave this region some scattered showers, but unfortunately most that really needed it got nearly nothing. More fields look stressed in the afternoons, some look stressed all day. There are some badly hurt fields in the region, particularly where compaction from spring work created issues. Corn on corn fields show more stress too, including some pollination reduction due to silk clipping. Fields near the Minnesota border look really good to me. Not many diseases can be found – some gray leaf spot in corn and a little frogeye in beans. Aphid numbers remain low, but lots of painted lady butterflies were committing suicide in my vehicle grill in Woodbury County last week while I was there. It is time to watch for spider mites, but so far, little reported.”
Paul Kassel (Region 2): “Crop conditions have headed two different directions across my area. Areas in Dickinson, northern Clay, Emmet, Kossuth and Winnebago Counties are seeing very good rainfall and growing conditions. However, areas in Clay, Palo Alto, Sac and Buena Vista Counties are currently very dry and are listed as abnormally dry to being in moderate drought on the U.S. Drought Monitor. I would expect that the area of moderate drought will expand when the new drought monitor map is released this Thursday, July 30. Fungicide applications on corn and soybean acres have been mostly completed. Soybean aphid numbers have been low so far. Gall midge activity has also been low with relatively few new discoveries.”
Corn from Winnebago County at the R3 or milk stage. Photo courtesy of Paul Kassel.
North Central Iowa
Angie Rieck-Hinz (Region 3): “Dry conditions persist in Calhoun and Webster County with D2 (severe drought conditions) and D1 (moderate drought conditions) impacting most of Humboldt, and D0 (abnormally dry) impacting most of Wright, Hamilton and Hardin Counties. Unfortunately, most areas missed rain this past weekend, and I anticipate seeing the U.S. Drought Monitor expand in size and severity, moving eastward and slightly north across the counties I cover. Most corn is R2 to R3, but I did find some corn (102-day maturity) that was starting to dent on July 27. This indicates to me that plant is suffering from lack of water and grain fill will be compromised. Overall, pollination seems to be good. Disease pressure continues to be low, and the fields I have been monitoring for rootworms have low adult rootworm beetle numbers so far. Soybeans are R4, with most pushing R5 (beginning seed) I continue to find thistle caterpillars, although at low numbers. Frogeye leaf spot is becoming evident in some fields.”
Meaghan Anderson (Region 7): “Most of Central Iowa received some rain in the last week, though most areas received less than an inch. While my eastern counties have been mostly in a sweet spot this summer getting enough rain (sometimes a little too much), we will need continued rainfall to finish out the crop. Some parts of Marshall County are now <25% of normal rainfall for the last 30 days and most of the rest of my area is <50% of normal. Corn is anywhere from R1 to nearing R4; in some cases, these stages are all happening in the same field. The western part of my area has some corn fields that are really beginning to burn up from the heat and lack of moisture; we’ve scheduled drought meetings for Boone and Dallas County next week, as well as a drought webinar series starting July 30. Corn rootworm beetles are emerging and I’m getting phone calls about concerning levels in both central and eastern Iowa. Corn earworms are beginning to make an appearance in fields. If you find them, check whether your corn hybrid should provide suppression and give your local field agronomist a call if it seems like it’s not working! Soybeans are mostly R3-R4 and look really good. Most fields now have closed rows, but I have seen a few fields with waterhemp sneaking through on end rows or in areas that looked to have been wetter this year. Now is a good time to evaluate why the waterhemp survived and make notes for next year. Most phone calls are about fungicide decisions in corn and soybean, potato leafhoppers in alfalfa, and dicamba injury to soybean.”
Tipping back on corn ears due to the dry conditions. Photo courtesy of Meaghan Anderson.
An earmworm found feeding on an ear in a Central Iowa field. Photo courtesy of Meaghan Anderson.
Aaron Saeugling (Region 10): “Sporadic rain showers have cover portions of SW Iowa in the past week. Some areas received a nice general rain while isolate areas have missed any measurable precipitation. For the most part corn looks very good where rain has not been limiting, and most corn is R2 to R3. While I would rate the disease pressure in corn to be low to moderate, fungicide applications are occurring. Soybeans range from R2 to R4, and I’m seeing sporadic insect feeding in soybean fields. Recently, I have been seeing heavy painted lady butterfly (aka adult thistle caterpillars) activity. Alfalfa is very slow to dormant in dry areas. Pasture conditions have been poor due to the hot and dry weather. With measurable precipitation I expect some crop conditions to improve over the next week.”
East Central, Southeast, and South-Central Iowa
Rebecca Vittetoe (Region 8): “This past week rainfall totals for parts of EC Iowa ranged from trace amounts to about an inch with some local areas getting a little more. Corn is mainly R1 to R3 and soybeans are mainly R3 to R4. In general, corn and soybeans are looking pretty good. I’m continuing to see more gray leaf spot pressure in corn, and I happened to find some southern rust in Washington County this past week. Japanese beetles, corn rootworms, potato leafhoppers, grasshoppers, and low levels of soybean aphids have been insects I’ve seen or gotten questions about this past week. Most questions this past week encompassed fungicide application decisions, insect pest concerns, and even a few dicamba related calls in soybeans yet.”
Southern rust found in a corn field in Washington County. Southern rust pustules are almost exclusively found on the upper leaf surface, are smaller and look more organge compared to common rust. Photo courtesy of Rebecca Vittetoe.
Virgil Schmitt (Region 9): “Rainfall last week was generally light, with the heaviest being less than 1.0 inch. In general, temperatures last week in the counties I cover and statewide were near normal. Most corn fields are at VT/R1 to R2. Soybean are mostly R3 to R4. Overall the corn and soybeans look good except from the storm damaged fields. Gray leaf spot pressure is increasing in corn fields. Katydids are starting to “sing.” Corn rootworm trait failure (continuous corn), Japanese beetles, dealing with storm damage to crops, and dicamba drift were common topics of discussion last week. I also had two unrelated calls from people who believed there conifers had been killed by dicamba drift. Upon questioning, both admitted to using “just a little” Tordon on brush amid the trees.”
Josh Michel (Region 11): “Light rainfall provided some minor relief as most of the region received 0.25 to 0.50 inch this past week. With the drier conditions corn, alfalfa, and pastures are continuing to show signs of stress. Corn mainly ranges from R1 to R3, with gray leaf spot being the dominant concern. There’s also been several field calls regarding Japanese beetle and corn rootworm feeding. Soybeans are currently R2 to R4, and generally look pretty good. The majority of soybean related field calls are centered around herbicide injury, defoliation estimates, and weed escapes. Hay fields and pastures continue to see poor growth from above average temperatures and limited rainfall. Many alfalfa fields are also seeing severe insect damage from potato leaf hoppers and grasshoppers.”
Alfalfa field in Davis County with severe potato leaf hopper feeding as evident by the yellowing of the leaves (aka hopper burn). Photo courtesy of Josh Michel.
Check out the map below to find your local ISU Extension field agronomist and find their contact information here!Category: Crop ProductionTags: crop updatefield agronomistsscoutingCornsoybeanspastureshaydroughtAuthor: Rebecca Vittetoe
By: Maddie McConnell, Danielle M. Clark (Wilson), and Emily Heaton
Growing up on his family’s farm, Steve Schomberg learned the importance of environmentalism by his father. Conservation and sustainability remained central to Steve’s life while he worked at the University of Illinois, which is where he first learned about miscanthus and its use as a biomass crop. When searching for a third, more environmentally diverse crop to grow on his farm, Steve decided to begin farming miscanthus for the University of Iowa Power Plant.
Iowa Farmer, Steve Schomberg with miscanthus field. Photo credit: Heaton Lab.
Thanks to the efforts of Steve and other local farmers, the University of Iowa is able to burn miscanthus instead of coal in their power plant. One acre of burned miscanthus produces the equivalent energy of four tons of coal. As an alternative to coal, miscanthus has a high carbon content and low mineral content resulting in a high energy potential. This high energy potential makes it a good option for sustainable and renewable energy and a great choice of biomass for the University of Iowa.
Miscanthus has proven to be highly effective when used for erosion control in fields to prevent soil leaching and at construction sites to prevent soil erosion. Erosion control socks at construction sites are stuffed with dried miscanthus. The socks are incredibly absorbent and will retain much of the rainwater. Once the miscanthus has absorbed the rainwater, the sock will become very heavy and difficult to move which keeps the neighboring soil in place. Additionally, miscanthus is woven into absorbent mats which are laid around construction sites. Miscanthus canes/stems do not decay as quickly as other grasses would if they were used for the same purposes.
Steve was drawn to miscanthus because of several attributes, including the ability to grow on different soil types and very little nutrient application to retain high yields. It takes about 5 years to maximize yields and should produce quality yields for 20 years. Unlike corn/soybean rotations, miscanthus fields have ground cover year-round to minimize soil leaching and erosion. In 2017, Steve decided to plant 15 acres of miscanthus as his own cash crop experiment. According to Steve, the initial risk has paid off with the returns over the last few years where miscanthus was sold for animal bedding and erosion control socks.
Steve is hopeful for the future of miscanthus and its uses as a biofuel, bedding, and erosion control. He believes energy companies that currently burn coal will eventually switch to burning miscanthus. He will continue to grow miscanthus and sell it for the use of bedding and erosion control. Eventually, he aims to grow up to 200 acres of his own miscanthus.
Product of ISU Biomass Undergrad TeamCategory: Crop ProductionTags: miscanthusfarmersAuthors: Danielle M Clark (Wilson)Emily HeatonCrop(s): Biomass and Forage
One option to consider in fields with severe storm damage with no or limited yield potential is annual forages. This option may especially be of interest to livestock producers who could utilize the forage or may be short on forage or feed as a result of the storm damage. The following recommendations are meant to serve as a starting point for those considering an annual forage in storm damaged fields.
Check with crop insurance. If your crop is insured, the first call needs to be to your insurance agent to get the field adjusted and determine insurance payments. The second question for your agent is what restrictions are in place for growing a forage crop. Are there restrictions on grazing or mechanical harvest, and are there any dates after which it can be grazed? Some will allow a cover crop to be seeded but not grazed until after November 1. Also, be sure your agent has released the field before destroying the field for a new crop.
Check pesticide labels. If you plan to graze or harvest a forage crop, be sure to check the labels on all pesticides, applied to the corn or bean crop. Two key points to check include when a forage crop can be planted (crop rotation restrictions) and when can it be consumed by livestock (grazing or forage restrictions). A handy resource to check pesticide labels for any potential restrictions is www.cdms.net/label-database.
Determine feed needs and how annual forages can help fill them. Warm-season and cool-season annual forages can help to stretching the grazing season and reducing the costs and stored feed needs.
Warm season or summer annuals such as sorghum, sorghum x suduangrass, sudangrass, and millets are the highest yielding and grow well in the heat of summer, provided adequate moisture is available for germination. They can be grazed or mechanically harvested as silage or wilted for baleage. Dry hay is not recommended with these summer annuals due to dry down difficulties. Prussic acid poisoning can be a concern with sorghum, sorghum x suduangrass, and sudangrass with frost in the fall. Tips for managing frosted forages with the concern for prussic acid poisoning can be found here.
If a summer annual is not able to be seeded by August 1, it may be worth waiting until mid-August to plant a cool season spring or winter annual instead. Spring annuals, like oats or spring wheat, can provide quick growth for fall grazing and don’t require any extra management next spring since they don’t overwinter. Winter annual, like cereal rye or winter wheat, will provide both fall/early winter grazing and early spring grazing, but they require termination in the spring prior to the 2021 grain crop. Legumes or brassica species could also be mixed with the cool season annuals; however, double check herbicide labels for any crop rotation or grazing restrictions.
With grazing, strip grazing helps to reduce waste of these forages. This can be accomplished with a single electrified wire moved weekly or twice per week. If strip grazing, start with the part of the field closest to the water source, and leave adequate forage residue for regrowth or protection from erosion.Crop ProductionTags: storm damageCornsoybeansforageAuthors: Denise SchwabRebecca VittetoeCrop(s): Biomass and Forage
Iowa State University Extension and Outreach in Pocahontas and Sac county will hold meetings to discuss the effects of the current drought on crops and livestock.
The Sac county meeting will be held on Thursday August 6 at the Sac County Fairgrounds 4-H Building at 416 Park Avenue, Sac City. Registration and refreshments will begin at 10:00 a.m. The meeting will start a 10:30 a.m. and adjourn at 12 p.m.
The Pocahontas county meeting will be held on Thursday August 6 at the Pocahontas Expo Center located at 310 NE 1st Street, Pocahontas, IA 50574.
Registration and refreshments will begin at 1 p.m. The meeting will start a 1:30 p.m. and adjourn at 3 p.m.
Speakers and topics include:
- Paul Kassel, Extension Field agronomist –crop moisture use, the US Drought Monitor, crop staging, yield prospects
- Beth Doran, Extension Beef Specialist –livestock topics, corn silage questions, forage alternatives
- Gary Wright and Tim Christensen, Extension Farm Management specialists – farm program and crop insurance topics.
- John Landgraff and Paul Berte, Farm Service Agency Executive Directors in Sac and Pocahontas - Farm Program topics that are drought related.
There is no cost to attend. Persons who are planning to attend are encouraged to pre-register by August 5. Please call the Sac County Extension office at 712 662 7131 or Pocahontas County Extension office at 712 335 3103.
Category: Crop ProductionTags: CornSoybeandroughtAuthor: Paul KasselCrop(s): Biomass and Forage
Low rainfall and high temperatures recently have caused some drought stress on local crops this summer. This is not wholly unexpected and there are some strategies crop producers can do to minimize the damage.
Higher nighttime temperatures cause plants to have higher nighttime respiration which in turn uses up sugars produced through daytime photosynthesis. Additionally, higher nighttime temperature speed up the number of heat units accumulated per day and lead to a faster grain filling period and earlier maturity.
A lack of moisture reduces corn biomass production by reducing cell expansion. Because corn silks have a very high water content, this stress could cause a delay in silk elongation. Slower or delayed silk elongation can result in asynchrony of pollen shed and silk receptivity (ie, silks emerge after pollen shed in most severe cases). The overall result is that poor pollination will occur due to the dry conditions. If these factors continue through pollination, kernel abortion will occur, causing exaggerated tipping back. Typically, tip back can occur into the blister stage but under most severe conditions tip back or kernel chips can result into the milk stage.
Drought conditions can result in soybean flowering to stop and even pod abortion. If weather conditions improve, flowering will re-initiate into the early seed filling stage and pod setting can occur into mid seed filling stage. Hence, rains in August can really benefit soybean yields.
Yield estimates on both corn and soybean are needed to make good decisions regarding harvest, storage and marketing decisions. While making estimates are straight forward:
Corn yield=earsacre*kernel rowsear*kernelsrowkernels per bushel
It is extremely important to factor in adjustments because of drought. The critical assessment in stress years is to adjust for seed weight. For example, 90,000 kernels per bushel is the typical estimate in non-stress conditions. However, in stress conditions, this should be adjusted to 105,000 or more kernels per bushel. And 2,600 beans per pound should be increased to 2,900 or more.
It is a good idea to plant cover crops following drought stressed corn or soybean for a few reasons. Cover crops will protect the soil and minimize the amount of soil water evaporation that occurs. Cover crops also help with flushing of accumulated nitrates if/when rainfall comes. To be successful with cover crop establishment in dry conditions, stick with cereal rye (winter hardy ahead of soybean or oats (winter kill) ahead of corn. This approach will limit water use in the spring which could be important if drought conditions continue through the winter. Soybean can withstand dryer conditions than corn plus allows more time for spring termination decisions to be made. And try to aerial, broadcast or drill seed ahead of forecasted rains and use the standard seeding rates.
First, be aware that drought conditions also are conducive for field fires. Make sure equipment is working properly and take precautions to avoid field fires. Ensure that combine settings are adjusted to account for smaller seed size, lighter seed weight and smaller stem/stalk diameters. Remember that grain lost in the field whether because of combine head loss or spread out the back of the combine can be problematic the following year.
Alternative Crop Use
Resources:Crop ProductionTags: drought stressCornSoybeanAuthors: Mark LichtZach ClemensCrop(s): Corn
Crop scouts and field researchers now have a new tool at their disposal to help correctly estimate disease severity and insect defoliation in field crops. The new online tool has been created by the Crop Protection Network and can be found at https://severity.cropprotectionnetwork.org.
This web tool will help scouts and researchers hone their assessment skills to accurately estimate the amount of a leaf covered by disease lesions and the amount of defoliation caused by insect pests.
Using expert information and interactive activities, the new tool presents several common diseases, along with a corresponding visual trainer and self-practice opportunities for assessing injury caused by each disease.
This screenshot of the web tool shows eyespot lesions covering approximately 20% of a corn leaf. The new web tool from the Crop Protection Network helps to train crop scouts and researchers how to more accurately estimate defoliation and lesion severity on field crops.
Other online tools and resources are available from the Crop Protection Network, including national disease loss reports and the ability to obtain continuing education credits for Certified Crop Advisors.
The Crop Protection Network (CPN) is a multi-state and international collaboration of university and provincial extension specialists, and public and private professionals who provide unbiased, research-based information to farmers and agricultural personnel. The goal of CPN is to communicate relevant information that will help professionals identify and manage field crop diseases and other crop production/protection issues.Category: Insects and MitesPlant DiseasesTags: diseaseestimationseverityinsectdefoliationAuthors: Daren MuellerAdam SissonCrop(s): CornMinor cropsSoybean
While parts of southern Iowa did receive some much needed rain, the western part of the state continues to be dry with parts considered to be in a D2 or severe drought. Besides the weather concerns, other common issues ISU Extension and Outreach field agronomists saw and heard about this past week in fields across the state included a potpourri of insect pests including low levels of soybean aphids, Japanese beetles, potato leafhoppers, and corn rootworms as well as gray leaf spot becoming more prevalent in some corn fields and isolated reports of tar spot in corn. Read on for more specifics about what’s happening in different regions across the state.
Joel DeJong (Region 1): “We had another week with limited rainfall in the area. There are concerns about the stress from this lack of precipitation and pollination. About 1.5 counties are showing the most stress – that area is at about 50% of normal rainfall from April 1. The rest lag normal but not by as much. Soybeans haven’t closed 30-inch rows in much of the area, and I’m not certain they ever will. Plants that had dicamba injury are slow to recover in the drier areas. Some corn rootworm injury discussions on continuous corn acres were held this past week. All these discussions were from fields with multiple Bt rootworm traits, leading to concerns about trait failures. Soybean aphids have been found in a few fields, but they remain at low levels at this time. Potato leafhoppers have been bad in alfalfa. Additionally, I had my first twospotted spider mite call, although I have not confirmed the damage myself at this time.”
Paul Kassel (Region 2): “Crop development continues at a rapid pace across much of the area. Corn is mostly pollinated, and the soybean crop is nearing the R4 or full pod stage. Rainfall and more importantly the lack of rainfall is a developing concern. Most of the weather reporting stations in the area report a rainfall deficit of about 1.5 inches for the month of July. Only two weather stations, Britt and Forest City, are reporting near normal rainfall for July. Sac City is reporting a 2.3 inch rainfall deficit for July. Farmers and applicators are applying fungicides to corn and soybean crops. Much of those fungicide applications will likely be completed this week.”
Pollination is nearly complete on this 109-day hybrid in Palo Alto County. Photo courtesy of Paul Kassel.
West Central Iowa
Mike Witt (Region 6): “Drought is the big concern in this part of the state with areas of Carroll, Greene, Audubon, and Guthrie Counties being the main areas of concern. Corn is mostly at VT. With the lack of rain and heat over the weekend, I have seen some fields shedding little pollen. Take time to check fields and see how pollination is going. There has been little disease pressure in corn, and on the insect side in corn I’ve seen some Japanese beetles and corn rootworm beetles. Soybeans are mainly R2 to R3 and seem to be holding their own against the heat and dry conditions. Japanese beetles seem to be prevalent in soybean fields. Hay fields and pastures are really struggling with the hot and dry conditions. Calls this past week have mainly been on growth regulator injury in soybeans and with concerns around the hot and dry conditions.”
U.S. Drought Monitor showing parts of western Iowa (and little part of eastern Iowa) showing up as a D0 (abnormally dry), D1 (moderate drought), or D2 (severe drought). Map released on July 16, 2020. Source: U.S. Drought Monitor.
Meaghan Anderson (Region 7): “Central Iowa received anywhere from about 0.1 inch to small areas of over 4 inches of rain in the last week. Again, the dry area seems to be missing all the rain, with Dallas and Boone County remaining particularly dry. Parts of Polk and Story Counties caught some wind with the storms that came through last week. Corn ranges from R1 to nearly R3, depending on planting date and location in field; there is a lot of variability. Most corn looks really good, but the dry areas are basically tapped out, especially in light soils. Gray leaf spot is getting a good start in a lot of fields. Soybeans are mostly R3 and while dry areas look pretty tough in the middle of the afternoons, soybeans seem to be growing well across most of central Iowa. Weed control has been fairly good, but many 30-inch rows are still not completely closed, providing the opportunity for weeds to sneak through later this season. I’ve found a potpourri of insect issues – Japanese beetles, thistle caterpillars, bean leaf beetles, grasshoppers - in soybean (and some of those insects in corn), though none have been at what I would call treatable levels. Most phone calls are about fungicide or insecticide decisions, potato leafhoppers in alfalfa, and dicamba injury in soybeans (yes, still).”
The dry conditions have really taken their toll on this corn field in central Iowa. Photo courtesy of Meaghan Anderson.
Soybean plant at the R3 stage, starting to put on pods. Photo courtesy of Meaghan Anderson.
East Central, Southeast, and South-Central Iowa
Rebecca Vittetoe (Region 8): “Rainfall ranged from trace amounts to 1.5 to 2 inches across my area this past week, with heavier amounts falling in my more southern counties. Corn seems to mainly range from R1 to R2, and soybeans are mainly R2 to R3. Gray leaf spot is more prevalent, especially in the lower corn canopy. A reminder that this disease favors warm and wet/humid conditions. While there have been reports of tar spot in corn, I personally have not seen it in a field yet. I’ve seen lots of fly poop that can easily be confused for tar spot, which is a good reminder to check and see if the spot wipes off the leaf. Also note that tar spot favors more moderate temperatures and wet/humid conditions. I’m seeing little disease pressure in soybeans currently. On the insect side, I’ve been seeing and hearing more about Japanese beetles in corn and soybean fields, corn rootworm beetles, and potato leafhoppers in hay fields. I’ve also had a couple of isolated reports of soybean aphids but at very low levels.”
The warm and humid conditions have provided a favorable environment for gray leaf spot to become more prevalent (photo taken 7/18/2020). Photo courtesy of Rebecca Vittetoe.
Virgil Schmitt (Region 9): “Rainfall last week was generally light, with the heaviest being less than 1.5 inches. In general, temperatures last week in the counties I cover were normal to three degrees above normal. Most corn fields are at V18 to VT/R1 and generally looking good except for storm damaged fields. Gray leaf spot is increasing. Soybeans are mostly R2 to R3, and in general they also look good outside of the storm damaged fields. Grasshopper nymphs continue to be observed in grassy areas and some winged grasshoppers can be seen. Corn rootworm trait failure (continuous corn), Japanese beetles, and storm damage were common topics of discussion this last week.”
Josh Michel (Region 11): “Some much needed and welcomed rain fell across the area last week. Most areas received 1 to 2 inches, with a few isolated areas receiving up to 3 inches. While the rain will provide some relief, alfalfa fields and pastures continue to show signs of stress. I have been seeing and getting many reports of insect damage, mostly due to potato leaf hoppers in hay fields. Forage quality and quantity continues to be less than average. Corn is generally looking good with many fields around R1 to R2. Signs of heat stress continue to be seen in most fields. Corn related field calls have consisted of more widespread gray leaf spot, isolated corn rootworm feeding, and Japanese beetle feeding. Soybeans are generally R2 to R3. I’m beginning to see some weed escapes in fields with shorter beans and with 30-inch row spacing. Soybean related field calls continue to be centered around herbicide injury, herbicide drift, insect feeding, and weed management.”
Severe potato leafhopper injury in an alfalfa field in SC Iowa. Photo courtesy of Josh Michel.
With several severe weather events in Iowa this month, reports of lodged corn are coming our way. Often times, a small part of the field is flattened and would be difficult to see from the edge. I encourage you to get out into cornfields and see how your stands look this month. In some cases, using a UAV camera to scan large fields is helpful. Evaluating root injury and adult activity is helpful for determining future management decisions.
Look for patches of lodged plants within cornfields. Photo by Erin Hodgson (17 July 2020).
Classic goosenecking injury caused by corn rootworm larvae. Photo by Erin Hodgson(17 July 2020).
In most cases, Bt traits are included in these fields with severe root injury. Continuous corn production fields are more likely to have economic injury from corn rootworm. Larval feeding can consume most of the roots and interfere with nutrient and water uptake; plus compromised roots make plants unstable in inclement weather.
Category: Crop ProductionInsects and MitesTags: scoutingIPMrootwormCornAuthors: Erin HodgsonAshley DeanCrop(s): Corn
Severe root injury directly translates to yield losses. Photo by Erin Hodgson (17 July 2020).
I was recently asked about an alien-looking caterpillar from central Nebraska. I occasionally see silver-spotted caterpillars in Iowa and wondered if you were seeing any in soybean?
The caterpillars are definitely a unique species because of the body coloration! The bodies are yellow-green in color and the head is brownish red. The caterpillars can make webbed nests similar to thistle caterpillar. They like to feed on locust trees, legumes, and wisteria.
Silver-spotted skipper caterpillar. Photo by Randy Anderson.
The adults have distinctive silvery markings on the wing edges. The wings are chocolately brown with banding, and about 2.5 inches wide. Likely there is one generation in Iowa/Nebraska. The adults like to feed on milkweed, red clover, and thistles.
Category: Crop ProductionInsects and MitesTags: caterpillarSoybeanpestIPMAuthor: Erin HodgsonCrop(s): Soybean
Silver-spotted skipper. Photo by David Cappaert, www.ipmimages.org.
While the western part of the state continues to be on the dry side, parts of central and eastern Iowa got hit with some storms this past week resulting in wind and hail damage. Besides the dry conditions and storm damage, herbicide injury in soybeans, gray leaf spot, potato leafhoppers, and low levels of soybean aphids are some of the issues ISU Extension field agronomists have observed this past week. Read on for more specifics for what’s happening in different regions across the state.
Paul Kassel (Region 2): “The corn crop is tasseling and silking across much of the area. I would expect the average pollination date will be around July 18 for the area. We are also short on rainfall with much of the area listed on the Drought Monitor as being D0 or abnormally dry. The soybean crop is reaching the R3 or early pod stage. Many farmers and commercial applicators are considering fungicide application to their soybean crop. Low levels of soybean aphids have been found near Sioux Rapids in Buena Vista County.”
Low levels of soybean aphids found near Sioux Rapids in Buena Vista County. Photo courtesy of Paul Kasse.
Meaghan Anderson (Region 7): “Central Iowa continues to have the “haves” and the “have nots”, with the worst areas receiving less than 0.5” of rain in the last 30 days. I’m hopeful the predicted rains this week will finally bring some to the driest parts of Dallas and Boone County. Corn is basically all pollinating, though development has slowed in dry areas and tassel appearance is still uneven. Most corn is really clean though grey leaf spot and common rust are easily found in some fields. Weed issues are still apparent under the canopy in several fields I’ve walked. Soybeans are R2 to R3 and still look quite nice, though we still see a lot of sunlight on the ground in a lot of 30” rows. Big concerns in the last week were the discovery of tar spot in a Polk County corn field (!!!!), more off-target plant growth regulator injury, potato leafhoppers in alfalfa (require treatment) and soybean (require watching), and a small but mighty population of thistle caterpillars in a few Jasper County fields."
Tar spot found in a Central Iowa corn field at very low levels. Photo courtesy of Meaghan Anderson.
Aaron Saeugling (Region 10): “Dry conditions persist over most of SW Iowa, which is causing corn to roll to conserve moisture. Corn is in the late vegetative stages and starting to tassel. The hot conditions are impacting pollination in some fields. Soybeans are coming along with most narrow row fields shading the rows. Hot spots of Japanese beetle feeding is occurring in some fields. I’ve received several calls on poor alfalfa regrowth related to several factors including herbicide carryover, insect feeding, lack of fertility due to dry conditions, and most of all limited rainfall.”
U.S. Drought Monitor showing parts of western Iowa (and little part of eastern Iowa) showing up as a D0 (abnormally dry) or D1 (moderate drought). Map released on July 9, 2020. Source: U.S. Drought Monitor.
Corn showing signs of drought stress. Photo courtesy of Meaghan Anderson.
East Central, Southeast, and South Central Iowa
Rebecca Vittetoe (Region 8): “This last week brought some storms across EC Iowa on July 9 and two rounds on July 11 that caused some pretty severe wind and hail damage in crop fields. The worst damage seems to be north of I-80, particularly in Linn and Jones counties. Most corn fields are either late vegetative or at VT/R1 and soybeans are mainly at R2 to R3. Over this last week, I’ve noticed more gray leaf spot starting to show up in corn fields. Remember this disease favors warm and humid conditions. Double check to make sure what you are seeing is gray leaf spot and that it’s not potentially bacterial leaf streak, as I’ve had a few more reports of that showing up in EC Iowa corn fields as well. Outside of some insect feeding (primarily Japanese beetles) and herbicide injury, soybean fields are looking good.”
Gray leaf spot has started to make its appearance within the last week. Photo courtesy of Rebecca Vittetoe.
Virgil Schmitt (Region 9): “Rainfall last week was variable in the counties I cover, ranging from less than 0.5 inch roughly south of Highway 92 to over 2 inches roughly north of I-80, with locally heavier or lesser rains. Several of the counties I cover sustained wind damage to corn in storms Thursday and Saturday evening and a large swath of hail on Saturday morning severely damaged crops in parts of Cedar, Jones, and Linn Counties. Second cutting hay harvest is mostly complete. Most corn fields are at V16 to VT/R1 and generally looking good, except for storm damaged fields. Soybeans are mostly R2. In general, they also look good, again except storm damaged fields. Grasshopper nymphs can be observed in grassy areas. Herbicide drift, potato leafhopper management in alfalfa, Japanese beetles, and storm damage were common topics of discussion last week.”
Josh Michel (Region 11): “While a few scattered showers did bring up to 0.25 inches of rainfall to parts of SE Iowa, dry conditions continue across most of SC Iowa. With continued above average temperatures and limited rainfall, pastures and alfalfa fields in many areas are showing signs of stress. Second cutting of alfalfa is mostly wrapped up, with many reports of lower than average yields and severe potato leaf hopper damage in some areas. Despite the limited moisture in some areas, corn is generally still looking good with most fields tasseling. In the drier parts of my area it is not uncommon to see corn fields with leaf rolling due to the heat and dry conditions. Farmers should be on the lookout for corn rootworm damage and silk cutting from Japanese Beetles. Soybeans are generally R1 to R3, and despite the limited rainfall are looking good as well. Most of my soybean related field calls continue to be centered around herbicide injury, herbicide drift, and insect feeding. I’m also seeing some soybean fields with 30-inch rows that will most likely not reach full canopy closure. This will most likely result in some late season weed escapes.”
Alfalfa field with some very severe potatoa leafhopper damage. Photo courtesy of Meaghan Anderson.
Hailstones damaged corn and soybean in multiple locations across Iowa on July 11, 2020. Fungicide use after hail injury is sometimes suggested as a way to benefit damaged plants. In order to help determine if fungicide use after hail is beneficial, Iowa State University undertook multiple years of research.
To summarize this research on reproductive stage crops:
Corn. Results from a three-year study suggest pyraclostrobin + metconazole application may not provide yield-increasing plant health benefits when applied after a mid-season (VT and R2) hail event when foliar diseases are not present at damaging levels. Results from this study support the claim that economic profitability from fungicide use in corn is more likely if fungicide application is for the purpose of disease management when disease risk is high. However, if you are applying a fungicide after hail injury to mid-season corn, waiting at least a week to apply the fungicide is more beneficial than an immediate application.
Soybean. Research suggests that hail injury at soybean growth stage R1 should not, by itself, be reason enough to make an application of foliar fungicide at R3 when disease risk is low.
Iowa State University’s hail extension publications include the above information, and can be downloaded for free from the Iowa State University Extension and Outreach Store.
Hailstones from a storm on July 11, 2020 that fell in Story County, IA.
Initial results for hail injury on vegetative stage crops have been summarized previously at ICM News: https://crops.extension.iastate.edu/blog/adam-sisson-alison-robertson-daren-mueller/would-fungicide-benefit-hail-damaged-cropsCategory: Crop ProductionPlant DiseasesTags: foliar fungicidefungicide applicationhailAuthors: Adam SissonDaren MuellerAlison RobertsonCrop(s): CornSoybean
The storms that moved across Iowa late last week and over the weekend brought rainfall, but they also brought some strong winds and hail. For those folks dealing with wind or hail damage, the first step should be to communicate with your crop insurance agent. Additionally, below are some resources that may be useful in evaluating the impact of the damage.
Hail damage to a soybean field and corn field in Eastern Iowa from a storm that went through the area on July 11, 2020 (photos taken on July 11, 2020). Photos courtesy D. Jordan, Linn County.
- Corn: Many corn fields were tasseling or were just starting to tassel (VT), which unfortunately is when hail can be the most injurious to corn. When evaluating the hail damage, consider the amount of defoliation as well as stalk bruising and breakage. The ISU publication IPM 78 Hail on Corn in Iowa shows how to obtain an estimate of the potential yield loss from hail injury to corn.
- Additional resource: Corn Loss Adjustment Standards Handbook (Crop Insurance Adjusters Handbook) (see pages 80 – 84)
- Additional resource: Corn Loss Adjustment Standards Handbook (Crop Insurance Adjusters Handbook) (see pages 80 – 84)
- Soybean: Most soybeans ranged from R1 to R3. Even when hail damage occurs at this point in the season, it is still best to wait 7 to 10 days to assess injury. The extent of the injury is based on stand loss, broken and cut stems, and defoliation. The ISU publication IPM 79 Hail on Soybean in Iowa walks through how to estimate the potential yield loss from hail injury to soybeans.
- Additional resource: Soybean Loss Adjustment Standards Handbook (Crop Insurance Adjusters Handbook) (see pages 62 – 67 and 71-73)
- Additional resource: Soybean Loss Adjustment Standards Handbook (Crop Insurance Adjusters Handbook) (see pages 62 – 67 and 71-73)
- Small grains (oats, wheat, rye, etc.): For those with small grains, Joe Lauer at the University of Wisconsin put together a good resource for evaluating hail damage, which can be found here: http://corn.agronomy.wisc.edu/WCM/W075.aspx.
- Forages: For those with hail damage to forage crops like alfalfa or red clover, Dan Undersander and Dan Wiersma at the University of Wisconsin explain how to evaluate the damage in this resource here: https://fyi.uwex.edu/forage/how-to-manage-hail-damaged-alfalfa-and-red-clover/.
- Fungicides for hail damaged crops: One of the big questions we often get with hail damage is whether to apply a fungicide as already planned, because of hail, or whether to forego the application completely. A common misconception is that hail-damaged crops will be at a higher risk for disease infection. Note that our fungal diseases like gray leaf spot in corn or frogeye leaf spot in soybeans do not require wounding to infect the plant whereas bacterial diseases will more commonly infect the plant through open wounds. Nathan Kleczewski, plant pathologist at the University of Illinois, did a nice job summarizing the research from various universities looking at the impact a foliar fungicide application has on hail damaged crops in this article here: http://cropdisease.cropsciences.illinois.edu/?p=1174.
Wind Damage Resources:
An Eastern Iowa corn field with wind damage after a July 9, 2020 storm (photo taken July 10, 2020). Photo courtesy of Rebecca Vittetoe.
Wind damage in corn varies from field to field, and it can be related to hybrid, corn growth stage, and other environmental conditions. Wind damage may have caused leaning, root lodging, or greensnap/brittlesnap. Like with evaluating hail damage, it’s best to wait a few days to fully evaluate how the plants are recovering. Plants that have leaning or root lodging should stand back up within a few days from the wind event if still in the vegetative stages. After tasseling and silking, the ability to stand back up is diminished. Wind damage to corn can also result in poor pollination due to additional plant stress and silks being covered by leaves.
For greensnap/brittlesnap, if the plants snapped off above the ear or where that ear would be, they could potentially still produce an ear from either the primary or secondary ear node; however, plants snapped off lower clearly represent a direct loss of yield potential. It is typically assumed that for each percent of plants snapped off equals a percent yield loss. This rule of thumb is slightly aggressive since neighboring plants can compensate with slightly higher kernel weights.
- Damage to Corn Plants by Strong Winds (Bob Nielson, Purdue University)
- Lodging: mid to late season (ISU Integrated Crop Management Article)
- Greensnap – storm induced stalk breakage (ISU Integrated Crop Management Article)
Category: Crop ProductionTags: Cornsoybeanswind damagehail damageAuthor: Rebecca Vittetoe
In 2018 and 2019, research was conducted on a relay intercropping and double cropping systems to evaluate as a possible alternative to Iowa’s traditional corn-soybean or continuous corn cropping system.
There were 2 sites; one near Kalona and another near Ames, Iowa, to study these possible alternatives. The Kalona site planted cereal rye immediately after corn harvesting. Following cereal rye harvest, soybean was double cropped. In 2018, the cereal rye yield averaged 46.1 bushels per acre and the double crop soybean yield averaged 23.2 bushels per acre. In 2019, the cereal rye yield averaged 30 bushels per acre and the soybean did not reach maturity and were not harvestable. It should be noted, that in 2018 there was an earlier than normal first fall frost.
Near Ames there were 4 treatments were: (1) soybean with winter wheat as a cover crop terminated before planting, (2) winter wheat-soybean relay intercropping with fall strip-tillage after November 1, (3) winter wheat-soybean relay intercropping with no tillage, and (4) soybean double cropped after winter wheat harvest. Wheat yields averaged 57.2 and 30.1 bushels per acre in 2018 and 2019 respectively. The lower yields in 2019 are attributed to cooler, wetter spring conditions. Wheat yields in 2018 were not significantly affected by the strip-tillage treatment, however, in 2019, the wheat yields in the soybean double crop system were significantly higher than either relay intercropping system (Figure 1). Soybean yields averaged 16.3 and 33.0 bushels per acre in 2018 and 2019 respectively. Wet conditions in the fall of 2018 resulted in delayed harvest and pod shattering. In 2019, the higher soybean yield was attributed to the soybean with winter wheat system and the lowest yield was in the double crop soybean system . The fall strip-tillage with the relay intercropping system did provide a higher soybean yield than with no tillage.
In conclusion, soybean and winter wheat (and likely other small grains) can be grown in a relay intercropping or double cropping system in Iowa but with increased production risk. Double cropping soybean following a small grain is very high risk because of much lower soybean yield potential due to early to mid-July planting dates and frost potential prior to reaching physiological maturity. A relay intercropping system reduces some of the risk associated with double cropping, but has some of its own risks. These risks are associated with being able to relay plant soybean into the small grain ahead of the small grain reaching the joint stage; harvesting the small grain before the soybean grow taller than the small grain heads; implement traffic can reduce the small grain harvestable yield; and drought conditions resulting in competition for soil moisture may be limiting for either or both crops. However, it is realistic to use an alternative cropping system to reduce risk of nitrogen and phosphorus losses while potentially increasing overall productivity.
Figure 1. Soybean (yellow) and winter wheat (red) yields under four systems: soybean with winter wheat as a cover crop (S w/ Wcc); winter wheat-soybean relay intercropping with fall strip-tillage (Relay ST); winter wheat-soybean relay intercropping (Relay); and soybean double cropped after winter wheat (Sdc).Category: Crop ProductionTags: relay intercroppingSoybeanwinter ryewinter wheatAuthor: Mark LichtCrop(s): Minor cropsSoybean