Incidence of diseases like tar spot can be mitigated during the growing season by employing field management practices and timely applying fungicide.
Whitlow says irrigation management is one strategy that can help reduce tar spot.
“You want to reduce the extended periods of wetness of the leaf,” he notes. “Research has shown that if the leaf is wet more than seven hours per day, there is a greater incidence of disease.”
Increased tillage might also help alleviate disease issues, but Whitlow says if neighboring fields have problems with tar spot, wind can spread the spores from farm to farm.
“Increased tillage reduces plant residue on the soil surface and, therefore, the overall number of spores available in a region,” Whitlow says.
Fungicide use in corn also offers an effective means for reducing the incidence of tar spot. Research data can be helpful to farmers for selecting the best product to help manage the disease, Whitlow says. Detailed test results can be found at https://cropprotectionnetwork.org/.
“Proper management is important because tar spot overwinters in the soil residue, so you need to reduce residue on the soil surface,” Whitlow explains. “Also, consider crop rotation because corn after corn on the same land will have more fungal disease problems.”
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