We established an experimental vineyard at the Agricultural Experiment Station in Geneva, New York comprised of cultivars of Vitis vinifera, V. labrusca, V. vinifera interspecific hybrids, and clones of V. riparia in 1998 to investigate the potential of using a tydeid mite Orthotydeus lambi (Arari: Tydeidae) as a biological control agent against grape powdery mildew Uncinula necator (GPM). Abundance of O. lambi per leaf exceeded 60 on some V. riparia clones and averaged 30 across all grape genotypes in 2001, representing nearly a doubling of the population each year since 1999. Grape genotypes with well-developed domatia (small tufts of hairs in vein axils on the underside of leaves) had the greatest mite densities. However, even on cultivars with small domatia, densities reached 20 mites per leaf in 2001. GPM on leaves of vines with only O. lambi (no GPM fungicides) was 60% of levels on control vines (no mites, no GPM fungicides) in 1999 (6.8% foliar infection verses 11.0% on control) but 20% of control vines in 2001(6.5% verses 33.2%). Similarly, GPM on clusters was about 7% of surface area for fruiting genotypes with O. lambi verses about 23% for control vines in 2000 as compared to less than 1% for vines with O. lambi verses about 20% for control vines in 2001. In 2001 we began trials to evaluate disease and arthropod control programs for commercial vineyards that were effective and also conserved O. lambi.
Species 1: Acari Tydeidae Orthotydeus lambi
Keywords: mycophagy, domatia
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