Stalk rot on corn.
Stalk rot on corn.

Stalk rots are common in the Midwest and are in every field to some extent. Identifying the specific type of stalk rot is easier during early stages of development, but becomes more difficult late in the season when multiple stalk rots become established in the same plant. Regardless of which stalk rot pathogen causes the primary infection, the end result is the same: yield loss due to lodging or premature plant death.

As with any disease, potential severity of stalk rots depend on the amount of inoculum present, a susceptible host, and environmental conditions that favor disease establishment. For stalk rots, inoculum occurs naturally in the soil and on plant residue for a large number of pathogen species. Stalk rot inoculum is highest in reduced tillage, corn following corn environments. Corn hybrids vary in susceptibility to certain types of stalk rot pathogens, but no hybrid is resistant to all stalk rot species. Weather largely influences which stalk rots are highest risk each year.

Stalk rots are becoming more apparent in this year’s crop. Fields at high risk include those with large kernel set at pollination followed by dry conditions after pollination, fields showing N deficiency, root lodged fields, fields with leaf disease and fields that were saturated. Inspect fields for stalk rots by pinching stalks six inches above the soil, splitting stalks and looking for shredded, discolored internal tissue or by scouting for premature dead plants. If stalk rot symptoms are found, harvest timing should be adjusted to avoid severe losses due to lodging.