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Integrated Control of Potato Leafhopper on Apple: Implications for Fireblight Management

Kathleen P. Leahy, University of Massachusetts Amherst

Abstract

The plant growth retardant prohexadione-Ca (Apogee®) is able to suppress the bacterial disease fireblight (causative agent: Erwinia amylovora) on apple, and shows some suppression of several other common orchard pathogens and insects. The potato leafhopper, Empoasca fabae (Harris), is a frequent pest of apple orchards in the Northeast and mid-Atlantic U.S., which can require multiple insecticide applications to control severe infestations, and which has been implicated in the dissemination of fireblight. The efficacy of prohexadione-Ca in suppressing potato leafhopper was compared with that ofimidacloprid (Provado™), a commonly used orchard insecticide, which is known to have excellent efficacy on leafhoppers. A factorial experiment with +/- prohexadione-Ca and+/- imidacloprid as the treatments was conducted, using a randomized complete block design, in two separate orchards over two growing seasons. Prohexadione-Ca and imidacloprid suppressed potato leafhopper feeding damage comparably in both.years, and an additional level of suppression was documented when both materials were used. It appears that commercial orchardists will be able to control potato leafhoppers with prohexadione-Ca using little or no insecticide.