Minor disease in most fields in most years. Stem terminal will curve, forming a crook. Lateral buds become brown and drop off. Brown discoloration of stems, beginning at nodes. Leaves are dwarfed and curl upward.
Pods often abort, or are underdeveloped.
Symptoms often develop first on plants near the edges of a field. Warm, dry conditions that favor vector development. Seed, possibly weed hosts. Thrips, dagger nematodes. Leaves may be puckered and misshapen, resembling 2,4-D injury.