Should I reduce residue to reduce corn disease?
Would "plowing it all under" eliminate the "real" disease problem? Residue has allowed inoculum to build in corn fields over time, but the presence of disease causing pathogens means nothing unless a susceptible host is present. When one considers the recent rise of once obscure corn diseases (Northern Corn Leaf Blight, Goss's Wilt, Diplodia, Etc.), one is forced to wonder about the industry's recent disease vigilance. Our love for certain hybrids to the exclusion of all others has probably allowed some pathogens to find a niche in which they can reside. The 2005 Field Guide to Corn Diseases notes another potential explanation.
That resource states the problem as follows…"In recent years, Gray Leaf Spot, Northern Corn Leaf Blight, and Diplodia Ear Rot have become problems because many elite hybrid germplasm pools" (the stuff from which our hybrids are derived) struggle with "resistance to…these diseases." Yes, residue does provide an overwintering site for some foliar corn diseases, but many of these diseases have reappeared because we have al little work to do on the resistance front.