Growers need to be alert to late-season corn diseases such as stalk rots, ear rots and foliar diseases such as Goss's wilt, says an expert at Pioneer Hi-Bred, a DuPont business.
Detecting late-season corn diseases as soon as possible, assessing their potential impact and harvesting early in some situations can help preserve grain quality.
"The warm, humid weather has primed the pump for fungal diseases in the later part of this growing season," says Scott Heuchelin, Pioneer research scientist, field pathology.
Heuchelin notes that when the crop reaches physical maturity, it stops actively growing and uses its energy reserves to fill the ear. "During this time, root and crown infections, established earlier in the year during saturated soil conditions, can take off and aggressively infect the plant's crown and stalk tissues," he adds.
If growers see tops dieback during ear fill, nutrients to the top part of the plant are possibly being cut off by crown or stalk rots, says Heuchelin. If top dieback is evident, test the stalk integrity by pinching the base of the stalk or pushing the plant to the side to assess lodging potential. Fields with significant lodging potential should be harvested first to preserve yield potential.
"If the ear leaf or husk leaves begin to bleach out, this could be a sign of ear rots," he says. "Fusarium, Diplodia and Gibberella are the main ear rots in the northern Corn Belt. Frequent precipitation events from tasseling through ear fill create ideal environments for Diplodia and Gibberella ear rots. Warmer temperatures during this wet period favor Diplodia and cooler temps favor Gibberella. Fusarium ear rots occur most frequently when corn experiences prolonged heat and drought-stress environments."
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