Management of Pear Psylla (Hemiptera: Psyllidae) Using Reflective Plastic Mulch

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.