As was the case in 2018 and 2019, tar Spot, a relatively new disease of corn, is again being reported in some fields. However, as was the case in the last two years, the disease is only now showing up, with the first reports coming in well after R5 (the dough growth stage). This is likely too late for it to impact grain yield and quality, as the greatest damage in terms of yield loss usually occurs when leaves are severely affected before grain fill is complete. There is nothing we can do about tar spot this late in the season, but it would be good to identify the disease and the affected hybrids so as to avoid planting that hybrid in an affected field next year. A more detailed article on tar spot development, spread, and survival can be found at: https://agcrops.osu.edu/newsletter/corn-newsletter/2020-03/tar-spot-corn.
Tar Spot Showing up Again in 2020
Crop Observation and Recommendation Network
C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.