Read the full article here >>> What Should I do About Tar Spot of Corn in 2023?
It didn’t take long this year to find tar spot in the Midwest. Over the last several weeks we have seen confirmed positives for tar spot in parts of Iowa, Missouri, Kansas, and Nebraska (Tar spot map). This is earlier than last year despite. With that said, the severity is extremely low and does not necessitate spraying fungicide at the moment! So what should you do?
My advice is to get prepared and make sure you have the tools in place to deal with this problem. As I said the last few seasons, tar spot is here to stay and we need to simply be prepared and ready to fight the disease. The first line of defense is to know if you have had tar spot before. This will tell you if there is resident inoculum sources present that can initiate epidemics. If you have seen tar spot on your farm before, then assume the pathogen is present and in close proximity to corn (the host). Remember the disease triangle? The last component of the triangle is the weather. If there has been conducive weather then the triangle has been met and risk is high for finding tar spots. So how do you know if the weather is conducive? Well, there is an app for that! Tarspotter and Field Prophet are both Smartphone applications that can help you determine if the weather has been conducive to put your corn crop at high risk of tar spot development.
So what weather is conducive for tar spot development? You are probably asking yourself this as we are in an epic drought, yet the forecasted risk of tar spot is high across the state. Well conducive weather for the pathogen it is different that the weather needed to grow corn. Yes, precipitation is helpful, but more importantly, we need intermittent wet/dry cycles to give us intermittent leaf wetness. Specifically leaf wetness at night. What gives leaf wetness this time of year other than rain? That would be high dew points and humidity.
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