Keep an eye out for eyespot
Whereas producers in southern Iowa are looking out for gray leaf spot, those in the northern half of the state should be watching for eyespot development. This disease is caused by the fungus Aureobasidium zeae. Conditions were good for eyespot in June, and it became prevalent in central Iowa. Recent hot weather is probably slowing this disease down considerably, and it is not severe yet in most fields. Still, it had an early start and is capable of causing significant yield losses. Symptoms are small round spots about 1/8 inch in diameter with a brown border and a yellow halo.