There are many unknowns regarding a particular corn disease – tar spot– which is still new to Northwest Missouri. Tar spot is caused by the fungus known as Phyllachora Maydis and can be identified by small, raised black and circular spots present on corn leaves, stalks and husks, according to extension. entm.purdue.edu. The black, round spots are known as fungal fruiting structures called stomata, each of which can produce thousands of spores. Many growers routinely apply corn fungicides. Tar spot pressure in corn is fueled by cool air around 60-70 degrees Fahrenheit, humid conditions – over 70% relative humidity and prolonged leaf wetness for nearly seven hours. Therefore, tar spot pressure is typically higher in areas such as those closer in proximity to the great lakes like Northwest Indiana, river bottoms and irrigated corn acres. It is also important to note that previous research has found that the pathogen that causes tar spot can overwinter on infested corn residue on the…