Stagger Planting to Weatherproof PollinationSpreading pollination over two or three weeks protects against bad weather and reduces pressure on your pest team and applicators. Staggering planting dates is easiest in regions with a long planting window. You might stop planting corn and plant soybeans for awhile. “Staggering maturities is easier, but there are two things to remember,” says Farm Journal Field Agronomist Ken Ferrie. “First, check each hybrid’s growing degree units to flowering—two hybrids might have the same maturity, but one will flower a week later than the other. Second, if you decide to plant early, midseason and late-maturing hybrids, plant them in that order, from earliest to latest. If you do the opposite, they might all flower in the same week.”
Manage Water to Weatherproof PollinationThe ability of silks to receive pollen after it falls from the tassel is affected by weather. “Hot, dry conditions reduce the viability of both the pollen and silk,” says Farm Journal Field Agronomist Ken Ferrie. “Most pollination problems during drought are caused by poor viability of the silk.” At the other extreme, prolonged wet periods slow pollination because tassels must dry out in order for the pollen sacs to open. “If you irrigate, try to apply water in the afternoon and evening, if possible, so the pollen sacs will have time to dry out during the peak of the day,” Ferrie advises. “Pre-loading water before pollination starts might reduce the need to water in the morning,” he adds. If you don’t have irrigation, you can still identify problems that affect future management decisions. “For example, don’t drop a hybrid because of low yield if the cause was poor ear fill resulting from unusual weather during pollination,” Ferrie says. With soybeans, too, managing irrigation can help mitigate the effect of stress. “But be careful,” he says. “Irrigation decreases the evapotranspiration rate, by raising the humidity and lowering the temperature in the canopy. That can affect soybean plants’ ability to hold pods. “In years when you don’t have a high evapotranspiration rate, it might be better to apply water from late afternoon through early morning and avoid the peak of the day. It’s not uncommon to see dryland corners outyield irrigated portions of a field because the evapotranspiration rate was lowered too much during the reproductive stage,” Ferrie adds.
Evaluate Nutrients While Scouting for PestsMidway through the growing season, a scout’s primary focus is on insects and diseases. But that’s also the perfect time to evaluate your nutrient planning. “Carry a scouting manual to help identify nutrient deficiencies,” says Farm Journal Field Agronomist Ken Ferrie. “Collect tissue and soil samples and check nitrate content to back up your observations.” If you discover low nitrate values in soil and plant tissues, and see deficiency symptoms, applying nitrogen as late as tasseling might reduce kernel abortion. “Plant uptake at this stage is only about 2 lb. of nitrogen per acre per day,” Ferrie says. “But the grain-fill process lasts for about 60 days, so you don’t want to run out. “In 2015, when central Illinois received 16" of rain in June, growers who applied nitrogen at tasseling still lost some yield, but the application produced 20 bu. to 60 more bushels per acre than they would otherwise have harvested.” If you document a nitrogen deficiency, consider why the deficiency occurred—was it specific to certain fields, management zones or hybrids? What should you do differently next year? Nitrate testing is just as key in a dry season, when you might discover unused nitrogen in the soil. Plant a cover crop to help carry it over to next season and prevent it from ending up in water supplies. With soybeans, the nutrient deficiencies you spot will be mostly micronutrients. “There’s no good soil test for micronutrients, so rely on tissue testing to confirm your observations,” Ferrie says.
Too dry, too wet and everything in between. This story is the seventh in an eight-part series on weatherproofing your crops. Follow along at bit.ly/weatherproof-crops