Verticillium Wilt

Very destructive fungal disease, poor growth and failed to set fruit as well as canes and leaves symptoms

Verticillium Wilt can be easily widespread and extremely dangerous. While raspberries and hybrid-berries are more susceptible to the disease, blackberries also are attacked by the pathogen but are not inclined to wilting. Verticillium Wilt is caused by Verticillium dahliae and Verticillium albo-atrum, a fungal plant pathogens.
These pathogens can exist in the soil prior to planting, may be brought in on planting stock, or may move with the wind. The pathogens can survive either in plant dead cuttings or free in the soil. The fungus enters the roots through breaks or wounds and moves into the vascular system, causing a systemic infection. After the plant or plant parts die, the fungus continues to survive in the soil for long periods.
Affected canes are stunted and leaves, starting at the base of the infected bushes, turn yellow, wilt and drop. The whole cane will languish and die shortly thereafter. Also canes might show a blue or purple streak from the soil line extending upward. Fruiting canes, infected by the Verticillium dahliae in the previous year, either die in the spring or develop yellow and stunted leaves. If the canes die before reaching maturity, the fruit becomes mummified. Initially, just one or a few canes on a plant may be affected, indicating that only a portion of the root system or crown has been damaged.
Factors that can increase disease are heavy soils and cold wet weather.
Verticillium is favored by cool weather and is most severe in poorly drained soils following a cool, wet spring. There are no effective fungicides for management once the plants are in the ground. Avoid land recently planted with tomatoes, potatoes, eggplants, peppers, strawberries, raspberries, or stone fruits.
This disease is virtually impossible to eradicate once it has been introduced into a field. Therefore, preventing its movement and establishment into clean fields is an important strategy for avoiding Verticillium wilt.