Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu
We are about 2-3 weeks away from finishing most of our corn. Currently grain is filling and the majority of photosynthate is being mobilized to the ears to support grain fill. This also is a time where stress can cause issues towards harvest. In particular, the effects of drought and disease on plant foliage can result in proportionally more carbohydrate reserves being moved to the ear, which results in less available to support the physiological functions within the stalk. A reduction in carbohydrates in the stalk may result in weaker stalks or stalks more prone to stalk rots and lodging. With recent heavy rains and more wet weather approaching, we may see some root/stalk rotting organisms picking up in activity during this crucial time in plant growth. This would be a good time to scout your fields, particularly dryland fields, to see where they stand in terms of foliar health, particularly the ear leaf, which contributes the majority of carbohydrates to grain fill. If your fields look like they are under a fair amount of stress then check back in another week or two to test for stalk strength. For more information on scouting and stalk rots on corn please see my factsheet posted on the University of Delaware Website: http://extension.udel.edu/factsheet/stalk-rots-on-corn/
We also have had some rust move into our corn. For more information see my article on my Field Crops Disease Management Blog: http://extension.udel.edu/fieldcropdisease/