Evaluation of Organic Insecticides for Harlequin Bug Management in Kale
Applied Research
Haley Sater
Agriculture Extension Educator; Agriculture and Food Systems
University of Maryland Extension
Salisbury
Abstract
Harlequin bug (Murgantia histrionica) is an important pest of brassica crops in the later part of the summer in the Mid-Atlantic region, and can cause significant feeding injury that reduces vegetable quality and marketability. Management of this pest is particularly challenging in organic production systems where insecticide options are limited and field-based efficacy data are scarce. A field trial was conducted in fall 2025 at the University of Maryland Lower Eastern Shore Research and Extension Center in Salisbury, MD, to evaluate several organically approved insecticides for harlequin bug management in kale. Treatments included an untreated control, neem oil, spinosad, and pyganic, arranged in a randomized complete block design. Six insecticide applications were made between August 29 and September 23, and harlequin bug adults, nymphs, and eggs were counted on six plants per plot 3–4 days after application. Neem consistently resulted in significantly fewer harlequin bug nymphs and adults compared to the control throughout the trial. Pyganic and spinosad reduced pest abundance on some sampling dates, when compared to the control. However, kale treated with neem oil exhibited noticeable leaf discoloration due to the neem oil's ability to strip wax from the kale leaves. These results indicate that neem may be an effective organic option for harlequin bug management, though potential impacts on crop appearance could affect marketability.
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Authors: Haley Sater, Emily Zobel
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Sater, H. Agriculture Extension Educator; Agriculture and Food Systems, University of Maryland Extension, Maryland, 21801
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Zobel, E. Agriculture Agent , University of Maryland Extension, Maryland, 21613