UW Soybean Plant Health
About white mold |
Scouting for white mold |
Life cycle of S. sclerotiorum |
Risk assessment |
Management - Overview |
Core recommendations |
Variety selection |
Rotation |
Weed control |
Row width and seed density |
Planting date |
Each year, the occurrence of white mold is heavily dependent on weather conditions during soybean flowering and early pod development. Rain, cool temperatures, high relative humidity, and moist soil favor the growth of the fungus if it is present. However, pathogen biology and crop management decisions interact strongly with weather to determine the risk of production losses caused by white mold (Table 1).
Table 1. Seasonal and long-term risk factors for white mold development
| Seasonal risk factors | Long-term risk factors |
| Weather Cool temps (< 85° F.), normal or above normal rainfall, field capacity or above soil moisture, prolonged morning fog and leaf wetness (high canopy humidity) at and following flowering into early pod development. |
Field/cropping history: inoculum of the pathogen will gradually increase if other host crops are grown in rotation with soybean; short intervals between soybean crops; soybean varieties susceptible to white mold grown. |
| Early canopy closure: due to early planting, high plant population, narrow rows, excessive plant nutrition and optimal climatic conditions. Dense canopy increases apothecia density. | Weed management: Poor broadleaf weed control; herbicides used in rotation systems may be suppressive to white mold. |
| History of white mold: population density of white mold pathogen; apothecia present on soil surface at flowering; distribution of pathogen/disease in the field. |
Topography of field: pockets of poor air drainage; tree lines and other natural barriers to impede air movement. |
| Soybean variety planted: physiological functions and plant structure govern reaction. | Pathogen introduction: contaminated and infected seed; movement of infested soil with equipment; windborne spores from apothecia from area outside fields. |
Maintenance of soybean plant health requires that management practices be tailored to specific fields, farm, or region. Reducing the risk of white mold and maximizing soybean yield in the presence of white mold can be achieved on a field-by-field basis by choosing management practices that
- prevent or slow the introduction of the white mold pathogen into a field
- steadily work towards reducing the population of the fungus in the soil
- provides a feasible compromise between lowering white mold potential and maintaining maximum yield potential.
Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: University of Wisconsin-Madison, Departments of Agronomy, Entomology, and Plant Pathology at www.plantpath.wisc.edu/soyhealth.