Generalist predators and true bug pests were monitored in the orchard groundcover and tree canopy from 1998 to 2002 in selected southern Oregon pear orchards which were in an IPM program. The most abundant generalist predators in the groundcover were often predaceous true bugs (e.g. Nabis alternatus and Orius tristicolor). Lygus hesperus, the primary true bug pest of pears, was much more prevalent in the groundcover than in the orchard canopy. A comparison of four groundcover mixes was conducted at the Research Center adjacent to a pear orchard, the plots were about 0.1 acre in size and a Latin square design was employed. The four groundcovers planted were: 1) a standard orchard sod consisting of companion grass, a mixture of fine fescue and perennial ryegrass, 2) a combination of companion grass and white clover, 3) a combination of companion grass and trefoil, and 4) a mixture of companion grass, white clover, trefoil, along with a blend of perennial broadleaf plants providing for a higher degree of plant diversity. Following successful establishment of the different groundcovers in 2000, the populations of pest true bugs and generalist predators were monitored throughout the 2000 and 2001 seasons using a sweep net. Plots planted to a sod generally had the lowest levels of both generalist predators and pest true bugs. The highest populations of L. hesperus were observed in the sod/trefoil mixture while the highest levels of pest stink bugs were found in the plots with the blend of perennial broadleaf plants.
Species 1: Heteroptera Miridae Lygus hesperus
Keywords: groundcover, pear
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