Corn Diseases Caused by Fungi

Corn is the largest agricultural crop of North America for commercial farm production. The corn used in farming and agriculture is often genetically engineered for resistance against major diseases and pests. However, there are still diseases and pests that affect corn crop growth and production. Diseases caused by fungi can destroy entire corn crops as well as individual plants during the growing season. Identification and early treatment is vital for protecting corn crops from the variety of fungal related diseases.

Anthracnose Leaf Blight

Anthracnose leaf blight is caused by the fungus Colletotrichum graminicol. According to the Ohio State University, Anthracnose leaf blight occurs in nearly all growing areas in the state of Ohio and accounts for some estimated loss of crop between 10 and 20%. Symptoms include water-soaked brown legions on leaves, stalk rot and top kill, states the Purdue University. The stalk rot phase of the disease is easily identifiably by shiny black linear spots on the corn stalk. This phase of the disease is most serious after leaf blight because it results in crop loss of the infected corn plant. The fungus thrives in warm, wet, humid conditions, but can also be found in cooler temperatures. The fungus attacks corn crops at any stage of development and is treated by using hybrid corn crops that have a lower level of susceptibility and by tilling infected crops, and doing a two-year crop rotation.

Corn Rust

Corn rust or common rust, caused by the fungus Puccinia sorghi, is a commondisease in sweet corn. The airborne fungus greatly affects young and growing plants later on during the growing season. According to the Cornell University, spores from affected corn plants travel through the air, and corn planted later on during the growing season are highly susceptible to the high concentration of spores in the air. Early symptoms include flecks on leaf surfaces, oval brownish powdery pustules on both sides of the leaf surfaces, and red to brown spores on the leaf skin, states the Purdue University. Common rust can greatly affect crops planted later on during the season, but do not survive on infected crops during the cold winter months. Treatment includes using hybrid corn species with a resistance to common rust, and the use of fungicides early on during the growing season.

Northern Corn Leaf Blight

Northern corn leaf blight (NCLB), caused by the fungus Exserohilum turcicum, is common during wet humid weather during the later months of the growing season. According to the Ohio State University, crop loss from NCLB can be as high as 30% to 50% if the disease infects the crops before tasseling. Long gray legions on leaf tissue can be noticed in as little as 7 to 12 days after the initial infection. Once lesions develop on the leaves, the fungus reproduces and spreads to other corn plants near the infected plants. The fungus develops best in warm and wet conditions, and during this ideal climate is when most infections occur. Treatment includes planting hybrid species of corn that have a resistance to NCLB and using foliar fungicides in seed production fields, states the University of Purdue. Because NCLB is devastating to crop yields, early identification and treatment is vital for preventing crop loss.

Sources:

http://ohioline.osu.edu/ac-fact/0022.html

http://vegetablemdonline.ppath.cornell.edu/factsheets/Corn_Rust.htmv

http://ohioline.osu.edu/ac-fact/0020.html

http://www.btny.purdue.edu/extension/pathology/cropdiseases/corn/corn1.html

Personal experience- I am planning on pursuing graduate studies in the field of agricultural economics and have taken classes cornering plant diseases and pest management.