Pear psylla, Cacopsylla pyricola (Förster), has remained the most challenging pest of commercial pears in Washington and Oregon, the top producers of pears in the United States. The lack of effective integrated pest management tactics for this pest has been a major barrier to effective management. In this study, we examined the potential for reflective plastic mulch affixed beneath pear trees to suppress pear psylla. In 2017 and 2018, single pear tree (cv. Bartlett) plots of reflective plastic mulch, black plastic mulch, and no mulch (check) were established in a research orchard to compare their effects on pear psylla. Arthropods were sampled every 7–14 d from March through late summer. In both years, reflective mulch plots had significantly fewer pear psylla adults, eggs, and nymphs of the first generation compared with black plastic and check plots. However, later generations of psylla were not suppressed by reflective mulch. Semi-field tests were conducted in 2019 and 2020 using uniformly pruned potted pear trees on either reflective plastic mulch or grass to determine whether summerform adults were tolerant to reflected light from mulch, or if shading from vegetative growth negated the effect of the mulch. In both years, significantly fewer summerform adults and eggs were found in reflective mulch plots, suggesting that shading, rather than summerform tolerance, reduced effects from reflective mulch in the summer. This study demonstrates the potential for reflective mulch to suppress pear psylla and justifies future examination as part of a season-long management program.

No abstract

Mexican bean beetle, Epilachna varivestis Mulsant, is a serious pest of snap beans, Phaseolus vulgaris L., in the eastern United States. These beetles are intolerant to direct sunlight, explaining why individuals are typically found on the undersides of leaves and in the lower portion of the plant canopy. We hypothesized that snap beans grown on reflective, agricultural polyethylene (plastic mulch) would have fewer Mexican bean beetles and less injury than those grown on black plastic or bare soil. In 2014 and 2015, beans were seeded into beds of metallized, white, and black plastic, and bare soil, in field plots near Blacksburg, VA. Mexican bean beetle density, feeding injury, predatory arthropods, and snap bean yield were sampled. Reflected light intensity, temperature, and humidity were monitored using data loggers. Pyranometer readings showed that reflected light intensity was highest over metallized plastic and second highest over white plastic; black plastic and bare soil were similarly low. Temperature and humidity were unaffected by treatments. Significant reductions in Mexican bean beetle densities and feeding injury were observed in both metallized and white plastic plots compared to black plastic and bare soil, with metallized plastic having the fewest Mexican bean beetle life stages and injury. Predatory arthropod densities were not reduced by reflective plastic. Metallized plots produced the highest yields, followed by white. The results of this study suggest that growing snap beans on reflective plastic mulch can suppress the incidence and damage of Mexican bean beetle, and increase yield in snap beans.