By Pierce Paul and Stephanie Karhoff
Many corn fields in Ohio are rapidly approaching silking (R1), and foliar diseases such as Gray leaf spot have been observed where the environment has been conducive to disease development, prompting growers to consider fungicide applications. The information below was developed by the Corn Disease Working Group (CDWG) as part of the Crop Protection Network. The Crop Protection Network is a a multi-state and international collaboration of university and provincial extension specialists, and public and private professionals who provide unbiased, research-based information to farmers and agricultural personnel.
The CDWG developed ratings for how well fungicides control major corn diseases in the United States. The CDWG determined efficacy ratings for each fungicide listed in the table below by field testing the materials over multiple years and locations. Ratings are based on the product’s level of disease control and does not necessarily reflect yield increases obtained from product application. A product’s efficacy depends upon proper application timing, rate, and application method as determined by the product label and overall disease level in the field at the time of application. Differences in efficacy among each fungicide product were determined by directly comparing products in field tests using a single application of the labeled rate. The table includes marketed products available that have been tested over multiple years and locations. The table is not intended to be a list of all labeled products. Additional fungicides are labeled for disease on corn, including contact fungicides such as chlorothalonil. Other fungicides may be available for diseases not listed in the table, including Diplodia, Gibberella and Fusarium ear rots. Many products have specific use restrictions about the amount of active ingredient that can be applied within a period of time or the amount of sequential applications that can occur. Read and follow all use restrictions prior to applying any fungicide.Source : osu.edu