Foliar Disease Can Threaten Yield
European corn borer used to be the main stalk-lodging culprit, but Bt hybrids have helped avoid that issue. Now the major cause of lodged stalks (after thunderstorms and straight-line winds) is foliar disease. In wet or humid conditions followed by high heat, anthracnose leaf blight can quickly progress to anthracnose stalk rot, for example.
Genetic selection is the first defense against foliar disease. Next is scouting and timely fungicide application with a product such as DuPont™ Aproach® fungicide, which can stop diseases from spreading to preserve photosynthetic activity and protect yield potential from many key fungal diseases.
Soybean white mold (video) is one of the most damaging and hard-to-control fungal diseases and can be found under the soybean leaf canopy. Look for white, fluffy growths on lower stems. This can lead to stem girdling and severely reduced yield potential, as plants lose their ability to transport nutrients for pod fill. When the disease is allowed to complete its lifecycle, white mold reproductive bodies, called sclerotia, can develop. These black, round, pea-sized bodies can contaminate harvested soybeans, and they can survive in the soil for years to infect future soybean crops. In contaminated fields, consider an application of Aproach® at the R1-R2 stage of growth when conditions are right for the development of white mold.
Septoria brown spot (video) on soybeans may show signs that include tan spots with chlorotic (yellow) halos. Infected leaves may turn rusty brown or yellow and drop prematurely, hampering pod fill.
Northern corn leaf blight (video) is now a threat in most of the Corn Belt. Heavy crop residue, moderate temperatures and rainfall set the stage for infection of lower leaves, which spreads into the upper leaf canopy. Large lesions can quickly reduce the corn plant’s photosynthetic capabilities and yield potential.
Gray leaf spot (video) is a greater threat on corn after rains, high humidity, fog and warm temperatures. Though gray leaf spot lesions start small, appearing between leaf veins, after about two weeks they can spread and coalesce to destroy much of corn’s leaf photosynthetic ability and threaten yield.
Common rust (video) spores can rapidly infect corn as they blow up on weather fronts from Mexico and frost-free southern areas. Corn growers should scout for dark brown pustules on upper and lower leaf surfaces.
DuPont™ Aproach® is not registered for use in all states. Contact your local DuPont sales representative for details and availability.
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