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Nursery
Volume 54 Number 18 Date 08/28/2009 ASTER YELLOWS - This leafhopper-transmitted disease was observed on Echinacea 'Harvest Moon' and 'Avalanche' in Douglas County. Symptoms of infection include abnormal flowers, irregular stem growth, and green, stunted ray and disk petals. The aster yellows phytoplasma persists in both wild and cultivated coneflowers and other perennial or biennial hosts over the winter months, thus infected plants may act as reservoirs next spring. Removal and destruction of symptomatic plants is the recommended control method. BALSAM TWIG APHID - Balsam firs in Pierce and Polk counties are showing twisted, distorted needles caused by this insect. While light-moderate amounts of needle injury are usually inconsequential, populations may build to economic levels if left unchecked. Horticultural oils applied to the eggs in fall or spring, or insecticides directed against the immature stages in spring, can provide adequate control. SPRUCE NEEDLE DROP - Numerous Colorado blue spruce trees in Langlade and St. Croix counties are reported to be lightly infected with spruce needle drop, also called sudden needle drop. The symptoms are well described by the name "needle drop", since this disease typically defoliates second-year needles, leaving behind only the newest growth. The fungus forms small, black, round spore-producing structures on the stems and bud scales of spruce. Distribution of affected branches is non-uniform and randomly scattered throughout the crown. As with most fungal diseases, measures that increase air circulation should reduce its occurrence. --Liz Meils, DATCP Nursery Inspector 
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