According to Kiersten Wise, and Charles Woloshuk, Purdue University Extension plant pathologists, the recent heavy rains and winds have caused extensive damage to areas of corn production in northern Indiana. Many fields remain flooded with the corn crop standing in several inches of water, and retailers and growers are asking about potential diseases that might threaten this corn.
“At this late stage in corn development the two disease threats are stalk rots, which will increase the chances of lodging and ear rots, which can reduce grain quality,” the pair stress in Purdue’s latest Pest & Crop Report.
“While the effects of standing water on stalk rot development are relatively unknown, root death and added stress caused by standing water will weaken late-planted corn and increase the likelihood that stalk rot pathogens will invade the plant,” they state. “Plants that had stalk rot before flooding occurred may become more severely diseased and may readily lodge if winds pick up.”
The pair note that if the floodwater was high enough to cover the ears or if ears lay in the water because of lodging, there is an increased risk of contamination from bacteria not commonly associated with corn kernels. Ears on upright plants that are not exposed to standing water are safe from these bacteria. “The only possible concern would be prolonged exposure to the high humidity generated by the standing water. Such conditions could promote growth of fungal ear rot pathogens at the tips of the ears,” they add. “Whether the rot spreads down the ear or results in mycotoxin contamination will depend on several factors including the conditions of the ears prior to the flood, the temperature in the days ahead, and how long until the floodwater recedes and the ground dries.”
Wise and Woloshuk advise Indiana growers to monitor flooded areas as well as the entire field for stalk rot and ear rots. “Fields or areas affected with significant amounts of ear rot should be harvested and handled separately,” they say. “Grain should be harvested early and dried to 15 percent moisture or lower.”
(Source: Purdue Pest & Crop Report)