Life History and Damage

Figure 41. Late-stage larvae will tunnel into all varieties of corn, including popcorn.

The life cycle of the European corn borer on popcorn is very similar to field or sweet corn. Popcorn is susceptible to European corn borer damage and will have considerable yield losses when infested during the plant growth stages from mid-whorl to 4 weeks after pollen shed.

Major European corn borer damage to popcorn is similar to damage in field corn. Yield losses from stalk breakage are particularly large when popcorn is infested during or after pollen shed and can average as much as 25 percent of the total yield. European corn borer causes very little direct damage to popcorn kernels, apparently due to the kernels' hard, starchy nature. Some loss is due to infestation of the ear shank (Figure 41) and subsequent ear drop.

Table 16 shows yield of IOPOP 12 popcorn hybrid (the most widely grown popcorn hybrid in the Midwest) in pounds per acre when infested by 0, 0.5, 1.0, 2.0, and 4.0 European corn borer egg masses per plant. Yield losses were considerable with just 0.5 egg mass per plant. Losses in excess of 1,000 pounds (23 percent) per acre can occur with 1.0 or more egg masses per plant (Table 16).

Table 16. Pounds per acre of IOPOP 12 popcorn after manual infestation with several levels of European corn borer egg masses (1983-1984; Polk County, Iowa, J. L. Jarvis).

-------------------------------------
Mean number 
of egg masses/plant     Yield (lb./A)
-------------------------------------
Infestation during whorl stage
0                       4,160
0.5                     3,575
1.0                     3,510
2.0                     2,990
4.0                     2,730

Infestation during pollen-shedding stage
0                       4,290
0.5                     3,445
1.0                     3,250
2.0                     3,120
4.0                     2,730
-------------------------------------