University of Illinois

No. 8/May 16, 1997

The Benefits of Conditioned Seed

A recent edition of the Illinois Seed News contained a statement that about 1 percent of the unconditioned seed in northern Illinois contained sclerotia (thick-walled survival structures) of the white mold fungus. These sclerotia, if "planted" with soybean seed, can introduce a serious disease problem into a field. Most evidence indicates that these sclerotia will not germinate and produce spore-bearing structures if they are buried one inch or more in the soil. The sclerotia produce a tiny flat-topped mushroom, which releases millions of spores, usually coinciding with soybean flowering. However, once in the field, white mold is difficult to control and manage. Fortunately, it is a serious problem only when temperatures are cool and there is frequent moisture (either rainfall or irrigation) in the field. White mold is becoming more common in northern Illinois and does appear in the central parts of the state, depending on weather conditions.

So, why take chances and use unconditioned seed? Sclerotia are visible and can be removed from seed lots with professional cleaning. They are similar in appearance to small, black pieces of wood or mouse droppings or blackened grape seeds. Some may be about the size of a soybean, while others are extremely small. Having a seed dealer clean and condition seed not only improves the crop performance but can also help keep certain fungal pathogens from the field.
H. Walker Kirby, Department of Crop Sciences, (217)333-8414