Blackberry Pests and Diseases

Fungal Disease

• Blackberries can develop a disease known as anthracnose, which is caused by the fungus Elsinoe veneta. This disease also commonly affects red raspberries, black raspberries and some types of hybrids. According to the University of Kentucky College of Agriculture, anthracnose causes blackberries to be extremely seedy and dry, and they may not develop fully. Another fungal disease that often affects blackberries is orange rust. Orange rust is characterized by bright orange pockets that are visible on the underside of plant leaves. Development of the fruit affected by this fungal disease is poor, and many plants do not bear any fruit at all.

Viral Disease

• Viral diseases can also affect the blackberry. According to the University of Kentucky College of Agriculture, viral diseases affect fruit production, reduce fruit quality and affect plant vigor. Impatiens' necrotic ringspot virus can affect the blackberry and causes symptoms such as mottling, ring spots, leaf deformation and mottling. Blackberries affected by this viral disease are often small in size and crumble easily. Impatiens' necrotic ringspot virus is spread from one blackberry plant to another by thrips, which are a common blackberry pest. Another viral disease that affects blackberries is tobacco ringspot, which causes stunted plants, reduced plant health and poor berry production. Blackberry plant leaves may develop yellow rings with this disease. Fruit that develops is usually dry, crumbly and small.

Pests

• Insects cause a great deal of damage to blackberries. Spider mites, leafhoppers, thrips, stinkbugs and Japanese beetles are a few of the insects that like to feed on blackberry plants. Fruit is often deformed from this feeding. Occasional damage from insects does not usually require treatment, states the University of Florida IFAS Extension. To keep severe insect infestations under control, the use of an insecticide is necessary.