In agricultural fields, last season's crop residue can result in poor stands, inconsistent plant sizes or yellow to light green foliage in recently sown crops.
As the plant material left in the soil from last season's crop decomposes, it releases many chemicals that are toxic to growing plants. If a crop is planted in a field before residue decomposition is complete, the crop may be damaged. The effect of toxic substances produced by one plant on another plant is called allelopathy.
Roots of affected plants will be discolored. The number and length of the roots also will be reduced. If the crop residue is toxic, roots will be discolored where there is contact with crop residue.
Distribution of symptoms within an affected field may be consistent with patterns associated with soil movement by farming equipment or may have a random distribution throughout the field. The condition will be more severe in lighter-textured soils, so symptoms may be more pronounced in areas with a sandier soil within a field.