the grain filling period, developing kernels become a significant photosynthetic
“sink” for the products of photosynthesis and respiration. Corn
plants prioritize the movement of these photosynthates to the kernels, even
at the expense of not maintaining cellular health of stalk, leaf, and root tissues.
The primary effect of severe stress on a corn plant (drought, heat, nutrient
deficiency, leaf diseases, insect damage, hail damage, consecutive days of cloudy
weather) is a reduction in photosynthetic rates. If photosynthetic capacity
decreases significantly during grain fill, plants often respond by remobilizing
stored carbohydrates from stalk and leaf tissues to supply the intense physiological
demand by the developing grain on the ears. In addition to physically weakening
the stalk of plants, remobilization of stored carbohydrates and/or the consequent
lower cellular maintenance of root and stalk tissues increases the susceptibility
of the plant to root and stalk rots.
Reports have already begun to trickle in from several areas of Indiana about
weak plants with varying degrees of root and stalk rot development. Growers
should monitor stressed fields the remainder of this month and into early September
for compromised stalk strength or the development of severe stalk rots and adjust
their harvest schedules accordingly to harvest these fields early in the season
before that one big storm brings the crop to its knees.
Shaner, G. and D. Scott. 1998. Stalk Rots of Corn. Purdue Univ. Extension Publication BP-59. Available online at http://www.extension.purdue.edu/extmedia/BP/BP-59.pm65.pdf (URL verified 8/23/05).
Vincelli, Paul. 2004. Factors That Could Enhance Stalk Rots in Corn. Kentucky Pest News (Aug 2). Univ. of Kentucky. Available online at http://www.uky.edu/Agriculture/kpn/kpn_04/pn040802.htm#corrot (URL verified 8/23/05).