Statewide survey of tar spot (Phyllachora maydis) distribution and intensity in Indiana
By Kaitlin Waibel
In 2018, tar spot was the third highest yield reducing disease of corn despite only being confirmed in only six states, but in 2021, another tar spot epidemic resulted in higher yield losses than any other corn disease in the United States and Ontario, Canada. Even within Indiana, the number of counties with confirmed tar spot presence has doubled from 2015-2021. The recovery plan for tar spot includes tracking tar spot movement and testing fungicide efficacy along with other collaborative efforts. Growers also use historical and seasonal disease presence information to make management decisions for their farm. Corn disease risk tools have been developed for to calculate the risk of tar spot infection, but disease presence has not been included in these tools.