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Optimizing Spinosyn Insecticide Applications for Allium Leafminer (Diptera: Agromyzidae) Management in Allium Crops
Horticultural Entomology
Document Type
Academic Journal
Source
Journal of Economic Entomology. April 2022, Vol. 115 Issue 2, p618, 6 p.
Subject
New York
North America
Language
English
ISSN
0022-0493
Abstract
Allium leafminer, Phytomyza gymnostoma Loew, has been a pest of allium crops in Europe for many years, but recently has become a serious concern in North America (Barringer et al. [...]
Allium leafminer, Phytomyza gymnostoma Loew (Diptera: Agromyzidae), is an invasive pest of allium crops in North America. Spinosyn insecticides, spinetoram and spinosad, have been effective choices for managing P. gymnostoma infestations in allium crops, but their use should be optimized for economical and resistance management purposes. In New York from 2018 through 2020, performance of each spinosyn insecticide was evaluated by making two applications spaced either 1 or 2 wk apart beginning at various intervals after P. gymnostoma was first detected in the field; a weekly spray program also was included. Results indicated that weekly applications of each spinosyn insecticide provided [greater than or equal to]98% reduction of P. gymnostoma densities in scallions and leeks relative to the untreated control. Spinetoram applied twice, regardless of initial timing and duration between sprays, provided an acceptable level of P. gynostoma control (71 to 98% reduction in densities relative to the untreated control). Spinosad also was effective when applied twice (85 to 95% reduction in densities relative to the untreated control), but not when sprays were made consecutively beginning when P. gymnostoma was first detected and not when the P. gymnostoma infestation was extremely high (i.e., 38 insects per plant in the untreated control). Management of P. gymnostoma with spinosyns can be successful with only two applications, but control tended to be best when first applied 2 to 3 wk after initial detection. Optimizing applications of spinetoram and spinosad will save growers time, reduce insecticide costs, and mitigate resistance development without significantly increasing the risk of yield reduction. Key words: Phytomyza gymnostoma, spinetoram, spinosad, Allium porrum, Allium fistulosum