Some insects use UV light for flight navigation and UV light reflectance patterns for recognizing host plants. Reflective materials placed on the ground or above plants may disorient certain pests so that they are deterred from landing on crops. Our objective was to evaluate the feasibility of using plastic mulches and plant covers with reflective surfaces to reduce thrips populations on 'Matsumoto' asters. Plots were established in cut flower fields in three commercial nurseries in major floricultural production areas in California. Treatments were reflective ground mulch, reflective cover, a combination of ground mulch with plant cover, and uncovered rows (control); there were four replications per treatment. In one nursery site, the plant cover was permanently set 1 m above the crop. In the other sites, the plant cover was continuously adjusted so that it was near the top of the plant canopy throughout crop production. Sticky cards and three plant samples around each card in plot centers were examined weekly. All thrips, predominately Franklinella occidentalis (Pergande), were counted on the sticky cards, and on three leaves plus a flower/terminal tap examined from each plant sample. Weeds in center plot grids were also counted. Reflective ground mulches protected the crop initially, but effectiveness was later reduced when the plant canopy covered the mulch. In the nursery where plant covers were set 1 m above the crop, the combination treatment was better than either reflective plastic treatment used alone. As plants matured and the canopy covered the ground mulch, overhead covers became more important at this site. In the other nurseries where reflective covers were adjusted to plant canopy height, thrips control results in the cover treatment were similar to the combination treatment. However, the combination treatment reduced weeds, an economic benefit not realized with the sole use of overhead plant covers.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA