Latin name: Verticillium dahliae and V. albo-atrum
Reason for Concern:
1) Caused by a soil-borne fungus, it reduces yields by wilting, stunting, and eventually killing the fruiting cane or the entire plant.
2) Usually a cool-weather disease and most severe in poorly drained soils following cold, wet springs.
Canes wilt and leaves turn yellow, then brown, and then die. Symptoms may be on only one side of the cane. If the canes are cut open, water-conducting vessels are usually reddish. Infected canes may die in one to three years. From the cane base upward, canes and leaves wilt; leaves yellow, then brown, and the cane defoliates except for a few top leaves. Symptoms may be on only one side of the cane. If canes are cut open, water-conducting vessels are usually red. Infected canes die in 1 to 3 years, and take on a bluish cast in raspberries. If canes survive winter, they may set fruit, but often collapse as fruit ripens or die before fruit matures. Symptoms on new canes frequently coincide with hot, dry mid-summer water stress. Lower leaves may be dull green as compared to bright green healthy leaves.
Caused by a soil-borne, it is most severe in cool weather and poorly drained soils following cold, wet springs. The fungus can survive many years overwintering dormant in soil and plant debris. In prime conditions, spores germinate and penetrate roots; breaks or root wounds aid invasion. The fungus grows into water-conducting root tissue, constricts circulation, and kills the plant. The tissue decomposes and returns to soil, completing the disease cycle. Root-lesion nematode can increase disease incidence and severity.