It’s been a rocky start to the 2024 growing season for many corn growers, with some parts of the Corn Belt enduring persistent rainfall, wind and hail. Those weather factors, along with rising temperatures and humidity levels, all play a part in the success of corn pollination, notes Ken Ferrie, Farm Journal Field agronomist.
Despite the struggles corn growers have encountered this season, Ferrie says any management and time you lavish on the corn crop as it goes through the pollination period is time well spent.
“Besides planting, pollination is one of the most crucial parts of corn production. Ideally, the ears will pollinate from their butt to tip in three to five days within a field,” he explains.
Ferrie says if pollination is extended past five days that’s when trouble can brew in the fields, costing farmers yield.
“If we get outside of that five-day window and the development of the kernels on the tip are a lot further down — or not as nearly as developed as the ones on the butt — they’re more likely to abort as we go into it,” he explains.
Scouting Provides Answers
The toughest early scouting situation is random and uneven plant growth within the row, which can be caused by poor planting conditions, poor planter operation, harsh weather or insects.
“Areas in the field with uneven growth are at high-risk for pollination problems,” Ferrie explains. “When you find varying plant sizes that don’t break down into identifiable maturity zones, you need to scout almost every day of the pollination window to make sure that all the plants get pollinated.”
Don’t sideline your scouting or aerial imagery efforts, even if fields look uniform early, he encourages.
“Between the V6 or V7 stage and tasseling, hail and high wind can stress the plants,” Ferrie says. “If you had rootworm feeding early or an insecticide failed, you might discover standability problems and goosenecking. These things can change a uniform field into a non-uniform field.”
Evaluate Insect Pressure
With uneven maturity, insects might be present throughout pollination and attack every plant. “They include silk cutters, such as adult corn rootworm beetles and Japanese beetles, as well as aphids, which interfere with tasseling and pollen drop,” Ferrie says.
Most silk-clipping insects are pheromone feeders. When they find a corn plant they like, they give off a pheromone that draws more insects to the feeding site.
“If you have 30,000 plants per acre, all pollinating at once, with good weather conditions, and you have 30,000 rootworm beetles, that’s only one beetle per plant,” Ferrie says. “They won’t be able to clip silks fast enough to create a pollination problem; the silks will outgrow the damage.
“But say you have 30,000 beetles per acre and 25,000 plants are pollinating this week. The insects probably still won’t create a problem. But if the remaining 5,000 plants pollinate just 10 days later, and all 30,000 beetles migrate to them, those plants probably won’t pollinate,” Ferrie says.
If you find 10 plants without any insects, and then find one plant covered up by insects, that plant probably pollinated later.
Base Treatment Decisions on the Environment
As you decide whether treatment is necessary, consider your environment.
“Under ideal environmental conditions, a crop can deal with a lot of aphids or rootworm pressure and still pollinate successfully,” Ferrie says. “If silk clipping is occurring, see if you have at least ½" of silk for the pollen to catch on to. Check whether silks have already pollinated. Cut the husk off an ear and shake the ear. Any silks that pollinated in the last 24 to 48 hours will fall off. If all the silks fall off, the ear is already pollinated, so there’s no need to spray.”
Ideal pollination conditions give you more time to make decisions. “If you see insects the first day, come back on the second day or the end of the week and see how pollination is progressing,” Ferrie says. “Silks grow ½" to 1" per day, so they might outgrow the pest.
“But if it’s hot and dry, silks won’t grow as fast; so if you see a problem, you need to react sooner.”
If pollination conditions are less than ideal, it’s wise to check with your aerial applicator before pollination begins.
“If it will take him two or three days to arrive that creates a dangerous situation,” Ferrie says. “You need to know this before you go to the field, rather than finding it out after scouting.”
Limited availability of applicators might force you to decide sooner about whether or not to treat, Ferrie says. If there are no aerial applicators available in your area, you might have to find an applicator with high-clearance ground equipment.
“With random uneven growth, you might find a situation in which the earlier plants in a field are starting to pollinate, but the later ones won’t pollinate for 10 days and silk-clipping insects are present,” Ferrie says.
“Under ideal pollination conditions, you might wait until about half the plants begin to pollinate, and then spray. But if the weather forecast is against you, or there are no applicators available and you see early signs of pollination problems, this might be a time to treat preventively.”
Other Reasons To Scout At Pollination
The high possibility the 2024 season will turn dry makes it even more important to scout your corn crop early and often. “In 2012, we could tell by the second week of July that some fields were not going to pollinate at all,” Ferrie recalls. “I wouldn’t have thought that was possible with today’s genetics, but that’s how bad the growing season was in some areas.
“By making that discovery early, growers who had oversold corn had time to react and buy back their contracts,” Ferrie continues. “Also, if you see a disaster looming, you can take photos to document that weather was the cause of poor pollination. The pictures will prove you did not fail to follow best management practices by not applying an insecticide to prevent silk clipping.
“It’s a good idea to notify your insurance agent as soon as you see a problem developing. That becomes especially important if a problem is localized, rather than affecting an entire county.”
Block out time for pollination scouting. Summer is a busy time, and the press of other activities sometimes causes farmers to neglect crop scouting just when it’s most important, during pollination.
