![]() ![]() At harvest, the overall appearance of infected plants is markedly different from that of healthy plants of the same cultivar. Fruit production and shoot growth on infected plants is significantly reduced. This pattern differs from symptoms caused by Blueberry shock virus (below), from which plants usually recover after exhibiting blight symptoms. Once plants become infected and show symptoms, they do not recover and will exhibit blight symptoms year after year. Symptoms first appear on one or a few branches, but the entire bush becomes infected within one to three years. The margins of leaves on the interior of affected bushes usually are chlorotic. ![]() Blighted blossoms are brown but bleach to a silver-gray as they weather. In some cultivars with some strains of the virus an oak-leaf pattern develops in the fall, but this symptom is easily overlooked. The cultivars Olympia and Stanley only exhibited a marginal leaf necrosis. Bluecrop develops a general chlorosis, and Jersey is the only northern highbush cultivar that remains symptomless. Blighted tissues, especially flowers, remain on the twig, or flag, and in some cultivars they may be present the following year if not pruned out. When shoots blight in the spring, they usually turn grayish-black, but when fully expanded leaves die back, they often turn orange-brown. In cultivars that develop severe symptoms, the flower clusters blight in the spring just as the flowers are about to open. ![]() BlScV has also been found in asymptomatic cranberry plants in the Pacific Northwest and in native black huckleberry in the interior of British Columbia. The disease has also been reported in Connecticut, Massachusetts, Michigan, New York and Pennsylvania, as well as in the Netherlands and Italy in Europe. The disease was first reported in British Columbia in 2000 and has since been found to be widespread there, while still limited in its distribution in Oregon and Washington. The virus is also the causal agent of Sheep Pen Hill Disease described in New Jersey in 1970. The disease has since been detected in three fields in Oregon and several more in Washington. Virus diseases of major importance in the Pacific Northwestįor photos and more discussion of blueberry viruses, see the Pacific Northwest Plant Disease Handbook.īlueberry scorch disease was first reported in 1980 in a field near Puyallup, Washington, and Blueberry scorch virus (BlScV) initially was characterized from two fields in Washington in 1988. There are no field treatments to cure a virus-infected plant. The use of certified virus-tested planting stock is the most important component of a virus management program. ![]()
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January 2023
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