A lot of corn is undergoing pollination across the Midwest this week and next. Ken Ferrie, Farm Journal Field Agronomist, offers some recommendations and reminders for consideration:
Corn needs ½” of silk to pollinate. If you’re seeing heavy Japanese beetle and/or corn rootworm (CRW) clipping, you may need to invest in some control measures – if you haven’t already.
Some of the fields Ferrie is most concerned about are planted to fully traited hybrids, which should be able to contend better with CRW pressure but in many cases aren’t, at least in central Illinois.
“If you have corn rootworm beetles thick enough to cause clipping issues in traited corn, you have full-blown resistance out there,” he says. “These are homegrown beetles in your field; they didn’t move in from a neighboring field.
“Rootworms don’t move much in luscious green corn,” Ferrie adds. “Rather, they move when a field is falling apart, and then they migrate to a neighboring field that poses a better place for them to lay their eggs.”
Perform pollination tests now and evaluate what you find. This simple test requires you to remove the corn husk and gently shake the ear. Any silk that falls indicates that corn has been pollinated within the previous 24 to 48 hours.
If a field is less than 50% pollinated, silks are clipped within ½" of the plant and you’re seeing an average of five or more beetles (either CRW or Japanese) per plant, it’s likely you need your aerial applicator to spray.
Ferrie adds that he is seeing an uptick in red-headed flea beetle populations in corn this year. Look for adults, which are small and oval shaped, about 0.2 inches in length, with metallic-black colored bodies and a red-colored head.
The beetle is feeding on corn leaves, and the damage looks similar to leaf feeding by CRW, he says.
Got short corn? That’s unlikely to impact yield. Ferrie says he is seeing a lot of corn that is shorter than normal. He attributes that to the three weeks of dry weather and high temperatures that occurred early in the season, causing the corn plants to “roll up” during the rapid growth period.
When rolling occurs, it allows an overabundance of sunlight to get down into the canopy which stunts growth and causes the corn plants to have shorter nodes between the leaves.
In addition, these shorter plants often want to fire a second ear, especially in upright hybrids. These second ears very seldom produce grain.
“Most of these (second ears) will abort as we get into grain fill,” Ferrie says. “Don’t count these in your decision on whether to spray for silk clipping. If the main ear is pollinated, don’t worry about that second ear.”
Ferrie adds that plant height usually has little effect on yield outcomes, and the shorter plants will actually improve standability this fall.
“What you will notice is the lower leaves below the corn ear will hang on longer, because they’re receiving sunlight and they’ll continue photosynthesis and producing food,” he says.
Don’t Neglect Scouting Soybeans
As soybeans go from the vegetative to the reproductive stage midseason, be on watch for yield loss. Look for insect pests in soybeans that can defoliate leaves and clip pods. Bean leaf beetles, Japanese beetles, soybean aphids and stink bugs look to take a bite out of your yield potential.
Bean leaf beetles defoliate leaves and scar pods. Consider insecticide treatment when: you have greater than 40% defoliation prior to bloom; 15% defoliation from blooming to pod fill; greater than 25% defoliation and active feeding at full pod; or 10% pod damage and 10 or more beetles per row foot.
Japanese beetles also defoliate but tend to skeletonize leaves by eating all of the tissue and leaving veins. It could make sense to use insecticide if you have 40% defoliation pre-bloom, greater than 15% from blooming to pod fill or more than 25% with active feeding at full pod.
Stink bugs typically show up mid-July through harvest. They damage pods by removing seed fluids, resulting in small, discolored and deformed seeds. If you grow soybeans for commercial production, consider treatment if you have 40 bugs per 100 sweeps (use a sweep net in different field locations) and pods are still green. Soybeans grown for seed production need to be treated sooner—if you see 20 bugs per 100 sweeps and pods are still green.
You can hear Ferrie’s complete recommendations in this week’s Boots In The Field podcast here:
