The twospotted spider mite is an important arthropod pest of greenhouse cut roses. Relatively little is known about the relationship between mite feeding, plant damage, and economic loss. About half of the annual pesticide use in this crop is typically directed against mites, which are foliage feeders that extract the cell contents from leaf parenchyma tissue, causing foliar stippling and disruption of the plant’s photosynthetic and water balance mechanisms. Twospotted spider mites also leave webbing on foliage and at high densities can move onto flowers, rendering them unsalable. Growers spray frequently for mites because of their serious injury and because mite populations can increase quickly in the greenhouse environment. There are no accepted sampling methods or thresholds for mites on roses, and thus there are no guidelines for timing sprays.
The objective of this study is to develop an economic injury level for twospotted spider mites on greenhouse cut roses that is based on the relationship between mite density and vertical movement onto the harvested flower, feeding injury, and yield loss. Preliminary results suggest that very high densities are needed to cause vertical movement onto the harvested flower. Much lower densities will cause visible injury and physiological injury.
Species 1: Acari Tetranychidae Tetranychus urticae (twospotted spider mite)
Keywords: economic injury level, greenhouse
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA