NATIVE HABITAT RESTORATION IN EASTERN WASHINGTON WINE VINEYARDS AS A PEST MANAGEMENT STRATEGY
Buckley, Katharine Denise
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Perennial crop systems such as wine grapes have begun using cover crops and hedgerows to increase beneficial insects and promote sustainable vineyard management in areas such as New Zealand and California. However, in arid wine growing regions such as eastern Washington, cover crops are often hard to grow and prohibitively expensive due to water costs. These studies were designed to determine if native plants, which require little or no irrigation, could be used to increase beneficial insect populations and enhance conservation biological control of vineyard pests in eastern Washington. Vineyards with some form of native habitat restoration in four different grape growing regions of eastern Washington were sampled using yellow sticky traps and leaf samples to monitor beneficial and pest insect numbers. These vineyards were compared with nearby conventional vineyards over a three-year period. Secondary pests such as spider mites were well suppressed in habitat-enhanced vineyards, though the primary pests, leafhoppers, were not. Most beneficial insect groups were found to be more abundant in native habitats than in vineyards, and were often significantly more abundant in vineyards with native habitat restoration over conventional vineyards. This indicates that native plants used as cover crops or in refugia patches may be a valuable addition to conservation biological control management strategies in arid areas. A partial cost/benefit analysis was also performed, which showed that habitat restoration may be more expensive in the short term than conventional pest control, although long-term benefits may outweigh costs. In a separate study to determine the best plants to use in habitat restorations, native and naturalized plants were evaluated for attractiveness to beneficial insects using clear plastic sticky traps. Plant attractiveness varied greatly by both insect group and time of year. Some native plants currently used to enhance beneficial insect habitat may not be the best option for growers in central Washington, and others such as sagebrush, Artemisia tridentata, may be far more important than previously realized.