Scorch
Blueberry
scorch virus
Annemiek Schilder,
MSU Plant Pathology
Bill
Cline, NCSU Plant
Pathology |
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Scorch is a serious
disease of blue-berries on both coasts of North America, but
it has not been found in the Midwest. In New Jersey, it is
also known as Sheep Pen Hill disease, which is caused by a
different strain of the same virus. |
| Blighted flowers are brown at first but later bleach to gray. |
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Symptoms
In some cultivars, a sudden and complete necrosis
of flowers and leaves occurs, while others remain symptomless. Twigs
may die back 4 to 10 cm. The scorched blossoms are often retained
throughout the summer. Severe infections can kill the bush. Symptoms
may be confused with spring frost injury or other blossom blights.
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| Leaf necrosis (above and below). |
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Some cultivars also exhibit marginal leaf chlorosis. |
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Disease
cycle
The scorch virus is vectored by aphids and
spreads quickly in the field in a radial pattern from a point
source. Eventually all bushes in a field may become infected.
The virus spreads readily to neighboring fields but usually
not more than a half-mile. Mechanical harvesters may spread
the aphids that carry the virus. |
| In Sheep Pen Hill disease, leaves often show a line pattern in the fall. |
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Management
Plant virus-tested, clean planting stock; test
bushes showing symptoms to confirm the disease; remove and burn
infected bushes; plant tolerant cultivars (these remain a source
of infection, however); apply insecticides to control aphids;
clean harvesting equipment.
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