|
Channel Field Check Up
KAYLISSA HALTER
EFFINGHAM, ILL.
Corn seedling disease symptoms may look similar to other environmental stresses, insect feeding, or herbicide damage. Seedling disease can occur in the form of seed rots, seedling blights, and/or root rots. If the root system is damaged, slow emergence, stunted or purple plants, and stand loss can occur. Pythium and Fusarium are two of the most common fungi associated with seed rot and seedling blight of corn.
Fusarium
Fusarium-infected plants can have tan to reddish-brown lesions on the roots and the root or mesocotyl may shrivel. Root symptoms range from very slight brown discoloration to dark black, completely rotted roots. This disease can occur under a wide range of temperature and moisture conditions. Fusarium root rot can move into the base of the corn plant resulting in crown and stalk rot at later growth stages.
Pythium and Rhizoctonia
Pythium infection is favored by wet, cool soils. Pythium can rot the seed prior to germination or rot the mesocotyl tissue of the seedling after emergence. Rhizoctonia-infected plants may have distinct sunken, reddish-brown lesions on the roots. Plants may be stunted or chlorotic, but often there are no aboveground symptoms.
Disease management
Management options are generally the same for all corn seedling diseases. Wet and cool soil temperatures (less than 50 to 55 F) can delay seed germination and emergence and predispose corn seedlings to disease. Seedlings become more susceptible to infection the longer a seed is in the ground before emergence and the more stress germinating corn endures. Be sure to plant high-quality seed at the appropriate planting depth and soil conditions to promote rapid germination and emergence. Fields that have good drainage and warm quickly should be targeted for earlier planting. Fields that have a tendency to stay wet or have a history of seedling disease should be planted slightly later in the season when soil temperatures are more favorable for germination.
Seed treatments
Seed treatment fungicides can provide a level of protection against seedling diseases, but may not eliminate all threats under severe conditions that promote infection. Most corn seed is treated with a fungicide seed treatment containing a combination of compounds that are active against a variety of seedling pathogens. Seed treatment fungicides have a limited period of activity, which is usually three to four weeks.
If you observe reduced stands, evaluate with your Channel Seedsman to determine if replanting is the best option.
http://www.channel.com/agronomics/Pages/Seedling-Diseases-in-Corn.aspx . ∆
KAYLISSA HALTER: Channel agronomist
|
|