My Blackberries are Looking Unhealthy. Are There any Pests and Diseases Common to Blackberries That may Have Affected Them?

Do the flowers of your blackberries have reddish, twisted petals and are there no fruit sets?

Are the fruits of your blackberries covered in a light gray fuzz?

Have the fruits of your blackberries failed to ripen or have they stayed red and sour?

Do the canes and leaves of your blackberries have purple spots on them?

Are the spots on the leaves sunken and moist?

Did the bright orange pustules appeared on the undersides of the leaves in the spring?

Are the canes of your blackberries turning yellow and dying in midsummer?

Do the canes of your blackberries have wart-like or corky swellings on them and are the canes dying?

Redish, twisted petals on flowers and absence of fruit sets usually indicate a fungal disease - double blossom. Other symptoms of double blossom are the appearance of witch's brooms (dense masses of deformed twigs with pale leaves). Remove and destroy infected canes as soon as you notice them. To help prevent the spread of the fungus, spray the whole plant with copper 2 or 3 times at 10-day intervals.

Fruits covered with light gray fuzz are caused by a fungal disease - fruit rot. This fungal disease is most problematic in wet weather, so thin your plants to allow good air circulation. Blackberries should be harvested often, and while doing so, you should discard any affected fruits.

If the fruit fails to ripen or has stayed red and sour, the most likely cause is insects - redbery mites. These microscopic insects can be controlled with the application of lime-sulfur spray once in early spring when new shoots are 1 inch long, and again after the canes have had 1 inch of new growth.

These symptoms are caused by a fungal disease - anthracnose. This disease causes problems mostly in cool and wet springs. In severe cases, twigs can die and defoliation can occur. All diseased leaves and canes should be pruned off, gathered and disposed of. Cut canes several inches below the damaged area. Early in the season, spray with lime-sulfur.

Leaf and cane spot diseases can cause purple spots on blackberries leaves and canes. All diseased leaves and canes should be pruned off, gathered and disposed of. Cut canes several inches below the damaged area. Early in the season, spray with lime-sulfur.

Bright orange pustules on the undersides of the leaves usually indicate a fungal disease - orange rust. This disease is incurable and can't be controlled by sprays. Diseased plants never recover but the disease can be transferred fast, so dig up and destroy all infected plants as soon as you notice them. Avoid planting blackberries in proximity to wild blackberries as they can carry orange rust.

These symptoms usually indicate a fungal disease - verticillium wilt. This soilborne fungal disease makes leaves yellow, wilt and fall off before the entire cane dies. Avoid planting blackberries near strawberries, potatoes, tomatoes, and eggplants as they are susceptible to verticillium wilt. Soil solarization may prevent the disease.

The most likely cause for this is a fungal disease - crown rot. This disease can't be cured, so remove and destroy all diseased plants including their roots. You can prevent crown rot by maintaining good soil drainage. Soil pH levels should also be above 6.0.

Borers often cause blackberries canes to die. These pinkish, up to 2 inches long larvae enter the cane at the top and tunnel down. In fall, remove dry leaves as they might carry borer eggs and destroy badly infected plants in spring. In spring, you can also dust the base of the plants with pyrethrin to kill emerging larvae.