Blueberry Bush Diseases
Blueberry bushes are native to the eastern part of North America. Rabbiteye blueberry bushes (Vaccinium ashei) grow in north Florida and southeast Georgia. Highbush blueberry bushes (Vaccinium corymbosum) grow in the eastern third of the United States and southeast Canada. Highbush blueberry bushes bloom and set fruit earlier than rabbiteye blueberry bushes. Most people cannot tell a difference in the taste, but rabbiteye blueberries have a firmer texture.
Care of Blueberry Bushes
Plant blueberry bushes in full sun and in well-drained soil. Allow at least 7 square feet for each rabbiteye blueberry bush and at least 4 square feet for each highbush blueberry. Use a 2- to 3-inch layer of pine bark mulch to hold in moisture. As the pine bark deteriorates, it will acidify the soil. Maintain a soil pH of 4.0 to 5.5. Apply lime to increase soil pH or sulfur to lower it.
Blueberry bush diseases result in smaller plants, smaller yields and sometimes even death of the plants. Incidents of infection are usually sporadic and preventative measures tend to work well. Since no variety is resistant to all blueberry bush diseases, choose varieties with resistance to the most common diseases in the area. Do not plant blueberry bushes in the shade. Keep the area around plants weeded to improve air circulation. Avoid excessive use of fertilizer, especially nitrogen.
Crown gall is a bacterial disease that forms bumps on the tops and roots of blueberry bushes. Infected bushes are usually stunted and weak. Treat with a suspension of hypervirulent Agrobacterium as recommended by the manufacturer. Bacterial diseases also cause cankers on flowers, leaves and shoots of wood less than a year old. Remove diseased plant parts and spray with a solution of Bordeaux mixture (copper sulfate and lime) following the manufacturer's directions.
Fungal diseases on blueberry bushes can be controlled by removing the infected plant parts and spraying with a fungicide as directed by the manufacturer. Gray mold causes leaf spots and blossom blight (deformity). Powdery mildew coats the stems, leaves and flowers of blueberry bushes with a white layer. Fusicoccum and Phomopsis cause cankers on blueberry bush stems, which results in the stems wilting and dying. Other fungal diseases cause shriveled or watery fruit and root rot.
Viral diseases commonly affect the leaves of blueberry bushes. Symptoms include reddish-brown spots on leaves or bright yellow and green mottling of leaves. Leaves may be cupped, twisted or elongated. Leaves and berries are smaller than normal on blueberry bushes with stunt virus. Berries on plants with shoestring virus turn purplish-red instead of blue. Blueberry bushes infected with a virus should be removed and burned.