Diseases of importance vary annually and from location to location. Occurrences of corn diseases that cause yield loss are influenced by many factors, including environment conditions, crop production practices, previous disease history, hybrid selection, and susceptibility to disease. Early detected corn diseases are important because grain loss decreases food, feed, and fuel production. Management for field corn, sweet corn and seed corn plant diseases is achieved through an integrated approach of best management practices and use of foliar fungicides and fungicide seed treatments. 

Numerous corn diseases, including those caused by fungi and bacteria, exhibit symptoms in the leaves. Fungal and bacterial inoculum can overwinter in crop residue on the soil surface and/or be spread by wind and water. Certain other pathogens must have a living host to overwinter, and spores must be carried on wind currents for new infections.

Foliar diseases that establish prior to tasseling, or become severe within two to three weeks after tasseling and pollination, can result in significant yield loss. Major diseases affecting the leaf that Taranis SmartScout can detect and tag include anthracnose leaf blight, common rust, leaf spot, eye spot, grey leaf spot, northern corn leaf blight, and smut. The estimated mean economic loss due to reduced yield caused by corn diseases in the United States and Ontario from 2016 to 2019 was US$55.90 per acre.