Common Disease or Fungus in Thornless Raspberry Plants

Raspberry Anthracnose

• Raspberry anthracnose is a fungal disease that lies dormant on the raspberry's old canes throughout the winter months. The fungal spores are moved onto the raspberry's young, developing areas by wind and rain and begin a series of continuous infections throughout the growing season. Raspberry anthracnose infects all areas of the raspberry, including the fruit, foliage, stems and canes. The infected raspberry plant develops gray lesions with purplish encasements on the canes and foliage. The raspberry plant experiences growth stunt, die back, cane destruction and heavy defoliation. Fungicide sprays are recommended to treat persistent anthracnose infections.

Cane Blight

• Cane blight is a destructive disease that enters the raspberry plant through its wounds. This blighting disease kills its hosting tissue, causing the infected areas to wilt and die. The raspberry's overall health is in jeopardy during cane blight infections. The infected plant will experience premature defoliation, wilting, die back and sudden death, if left untreated. Manage cane blight by growing certified, virus-free plants, and give them full sun, proper fertilization and a weed-free environment.

Verticillium Wilt

• The thornless raspberry plant is highly susceptible to verticillium wilt. This soil-borne fungal disease infects the raspberry's vascular system through its roots. The infected vascular system becomes restricted and its tissues become unable to transport water throughout the plant. As a result, the thornless raspberry becomes starved. The raspberry's foliage wilts, turns yellow and eventually defoliates. The stems and canes become streaked with a purplish line that runs from the soil line. The thornless raspberry is always killed by verticillium wilt infections and chemical treatments are not effective in controlling or preventing this fungal disease.

Considerations

• Growers should take steps to protect their thornless raspberry plants from infectious diseases. Reduce the number of infectious fungal spores in the raspberry's planting area. Provide plenty of room between each planted raspberry to allow ample circulation throughout the plants. Always keep the raspberry's area free of debris and defoliation. Water the plant deeply and infrequently, as this raspberry is intolerant to wet feet. Remove all fruit from the thornless raspberry during its final harvest and prune the spent canes. Protect pruning cuts from fungal invasions by sealing the wounds with pruning paste. Speak with a nursery or horticultural specialist about chemical controls since fungicides can cause the raspberry more harm than good when applied incorrectly.