EFFECT OF UNDERSTORY AND BORDER VEGETATION COMPOSITION ON PHYTOPHAGOUS AND PREDATORY MITES IN MASSACHUSETTS COMMERCIAL APPLE ORCHARDS

Ground cover and border composition were determined using ordination in 28 Massachusetts commercial apple orchard blocks. The presence or absence of phytophagous and predatory mites was recorded after 2 min timed scans of ten randomly selected apple leaves and of the five most commonly occurring plants at ten aisle, row, and border sampling sites. Orchard ground cover vegetation was very diverse. Grasses were the predominant groundcover in aisles, with broadleaf plants predominant in the rows. Orchard borders were somewhat less diverse than the orchards themselves. Rubus spp. were the most frequently occurring border plants. All types of phytophagous and predatory mites examined were significantly more likely to be found on herbaceous forbs and woody plants (dicots) than on grasses (monocots).