(August 2008) In a season with ample rainfall and warm temperatures, there are numerous diseases that can show up in a corn stand and dramatically impact yields. So far in 2008, anthracnose is the disease to be wary of in the Midwest and north central states, as it's turning up in fields throughout the region.

Anthracnose can infect corn early through leaf blight or later in the season via stalk rot or top die-back. Leaf blight symptoms begin with water-soaked, oval lesions that grow to about half an inch with tan centers with reddish-brown borders. Usually found on lower corn leaves early in the growing season, it makes its way to upper corn leaves late in the growing season.

Fields with high leaf blight levels should be scouted for anthracnose stalk rot later in the season. Anthracnose stalk rot is distinguishable from other stalk rots due to the dark, shiny lesions on the stalk rind.

"When gauging the severity of stalk rot, producers should slice a stalk down the middle and inspect the interior," explains Gary Nowaczyk, CROPLAN GENETICS® brand product manager. "If creamy white moisture is observed, the plant is strong. But, the plant is showing signs of collapsing if the inside of the plant is dry and light gray to grayish green in color."

Corn-on-corn acres are particularly susceptible to anthracnose, so the most effective method of preventing the disease is to till fields and rotate crops. Resistant hybrids, which tend to be full-season maturities, can also be planted. However, hybrids with resistance to the leaf blight phase may not be resistant to the stalk rot phase, and vice-versa. Therefore, it's advisable for growers to work with their local seed specialist to select hybrids with the proper leaf blight and stalk rot resistance, with good standability and high yield potential.

While there are no fungicides currently labeled for curing the anthracnose pathogen, Headline® can be utilized for its preventative properties.

"The best time to spray is when the corn is brown silking, because a surfactant or oil can be used to increase uptake," Nowacyzk says. "The challenge, however, is that a lot of growers have uneven corn stands this year, making it tough to know when to spray. Therefore, it's advisable to wait until 100 percent of the field has tasseled."

"Fungicides are usually applied on hybrids for the specific purpose of preventing or eliminating disease, but fungicides can also help maintain the plant intactness of fast-die, fast-dry genetics, helping them to keep standing until harvest," he adds.
For more information about managing anthracnose and other diseases, your local AgriSolutions™ expert agronomist and CROPLAN GENETICS® seed specialist have you covered. Turn to your local seed specialist and check out your local Answer Plot® location as a third-party source to help sort out the other brands and find the answers for your toughest field.