Growers need to be on the watch for seedling diseases in corn and soybeans. Damping off of the seedlings can be seen now, according to Alison Robertson, associate professor of plant pathology, Iowa State University. Damping off is a complex of pathogens that attack the seedlings, as shown in the photo. A corn seedling with damping off is on the right.
At Syngenta’s Seedcare Plot Tour in Iowa, Robertson said she’s seen damping-off problems in corn and soybean that have been caused by Pythium. Conditions during germination will determine what pathogens are involved in the damping-off problem, she added. Here are the most common pathogens and ideal conditions:
* Pythium with flooded soils and cool soil temperatures from 50 to 60°F.
* Phytophthora with flooded and warm soils with soil temperatures in the 70°F range.
* Fusarium with wet and cool soils with temperatures in the 50°F to 60°F range.
* Rhizoctonia with damp and wet soils and warm soil temperatures, 70°F to 80°F.
Other conditions that add to disease trouble, Robertson said, are planting soybeans early in no-till or reduced-till fields, a history of seedling diseases in the field, and poorly drained soils. Low seeding rates and lower germination also are risk factors for damping off.
Treatment for seedling diseases is a seed treatment fungicide. Robertson recommended that growers get the pathogen identified and then use a seed treatment on the crop in the field in the future.