Blackberry Diagnostic Tool

General Decline in Plant Vigor

The cause of decline in vigor without visible symptoms is very difficult to diagnose. Many possible causes exist, most of which will lead to visible symptoms over time. Some of the more common are:

1. Virus infection

Viruses occur mainly in older plantings, or in plantings where clean nursery stock was not used. Special tests are required to diagnose the presence of virus, and these tests produce many false negatives. Symptoms usually appear only after infections are severe.

2. Root damage

Sublethal root infections from Phytophthora, feeding of dagger or root lesion nematodes, feeding by grubs, and crown gall will cause a general decline in plant health. Dig up plants and examine the roots for lesions and feeding damage, and conduct a nematode test.

3. Nutrient deficiency

Nutrient deficiencies have not been documented in the southeastern U.S. Soil and leaf analysis can be used to identify if a nutrient(s) is deficient.