he current USDA corn per acre yield estimate for Indiana puts the Hoosier State squarely in first place among the major corn producing states and is identical to the final yield estimate of 147 bu/ac for the 2000 crop. What triggers this fearmonger alert is the memory of last years near epidemic of stalk rots that accompanied the high yields. While Ive not heard of any significant discoveries of stalk rot yet in this years crop, I nonetheless believe folks should spend some time walking fields during the next several weeks to confirm that the problem is not developing.
Conceptually, the potential for stalk rots to develop when yield potential is high is due to the fact that high yield potential requires a lot of output from the photosynthetic factory that we otherwise call a corn crop. If stress of any kind during the grain fill period severely limits the photosynthetic output, the corn plant is more likely to remobilize stored carbohydrates from the lower stalk reserves to the developing ears. When the carbohydrate concentration declines in the lower stalk and root tissues during grain filling, the plant becomes more susceptible to the development of root and stalk rots.
Last years stalk rot outbreak was the result of several plant stresses during grain fill including significant loss of healthy leaf tissue due to diseases and significant drought stress beginning in late July. By early August last year, stalk rot symptoms were evident in many fields and quickly became a major problem during the harvest period.
Fortunately, this years crop is generally healthier than last years crop. Soil moisture conditions, on average, are also more favorable at this moment. Indeed, few if any reports of stalk rot have come to my attention.
Nonetheless, if you know that certain fields or areas within fields have been under considerable stress during the past few weeks AND the yield potential of the field was heretofore pretty darn good, it would behoove you to spend some time walking those fields and inspecting the condition of the lower stalks. The inspection technique is simple: Squeeze the lower stalk. If it collapses easily, youve got trouble. If you cannot squeeze it easily, youre probably okay.