Blueberry Stem Blight Info
More commonly referred to as ‘blueberry dieback’, stem blight on a blueberry is caused by the fungus Botryosphaeria dothidea. The fungus overwinters in infected stems and infection occurs through wounds caused by pruning, mechanical injury, or other stem disease sites. Early symptoms of stem blight on a blueberry are chlorosis or yellowing, and reddening or drying of foliage on one or more branches of the plant. Inside infected stems, the structure becomes a brown to tan shade, often on only one side. This necrotic area may be small or encompass the entire length of the stem. Symptoms of blueberry dieback are often mistaken for winter cold injury or other stem diseases. Young plants seem to be most susceptible and have a higher mortality rate than established blueberries. The disease is most severe when the infection site is at or near the crown. Usually, however, the infection does not result in the loss of an entire plant. The disease normally runs its course as the infected wounds heal over time.
Treating Blueberry Stem Blight
Most stem blight infections occur during the early growing season in spring (May or June), but the fungus is present year-round in the southern regions of the United States. As mentioned, generally the disease will burn itself out over time, but rather than risk the possibility of losing a blueberry crop to infection, remove any infected wood. Cut off any infected canes 6 to 8 inches (15-20 cm.) below any signs of infection and destroy them. Fungicides have no efficacy with relation to treating blueberry stem blight. Other options are to plant resistant cultivars, use disease free planting medium, and minimize any injury to the plant.
