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TWOSPOTTED SPIDER MITES | |
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Twospotted Spider Mite (Acari:
Tetranychidae) in Peppermint: Population Dynamics and Influence of Cultural Practices¹ CRAIG S. HOLLINGSWORTH² AND RALPH E. BERRY Department of Entomology, Oregon State University, Corvallis, Oregon 97331 © Copyright 1982 Entomological Society of America ABSTRACT Environ. Entomol. 1 1: 1280-1284 (1982) Populations of the twospotted spider mite, Tetranychus urticae Koch, declined abruptly on peppermint, Mentha piperita L., after reaching a peak density during late June in southwestern Oregon and during early August in central Oregon. Populations were highly aggregated in all leaf strata at the beginning of the season when mite densities were low, but dispersed as density increased, especially on top leaves. Distribution became more random during population outbreaks. Fall plowing delayed mite population development the following summer by nearly 1 month. Fall flaming with a propane burner reduced T. urticae density, reducing the probability of an early outbreak of mites the following season. The impact of predators on T. urticae in commercial peppermint fields is examined. Spider mite populations in the laboratory increased rapidly on water - stressed peppermint plants, but not on plants stressed by Verticillium dahliae (R & B). |