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United States Department of Agriculture

Agricultural Research Service

Research Project: Reducing the Impact of Diseases on Hop Production

Location: Forage Seed and Cereal Research

Title: Suppression of Hop Looper (Lepidoptera: Noctuidae) by the fungicide Pyraclostrobin

Authors
item Woods, J -
item Gent, David

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2014
Publication Date: April 30, 2014
Citation: Woods, J.L., Gent, D.H. 2014. Suppression of Hop Looper (Lepidoptera: Noctuidae) by the fungicide Pyraclostrobin. Journal of Economic Entomology. 107(2):875-879.

Interpretive Summary: The hop looper is a pest of increasing importance. In this research field experiments uncovered that a fungicide commonly utilized for control of powdery mildew, pyraclostorbin, was inhibitory to the hop looper and minimized defoliation from feeding of the pest. The insecticidal activity of pyraclostrobin was found to be unique among fungicides evaluated in the same chemical family. A single application of fungicides containing pyraclostrobin applied for disease control in late July to early August may be a novel means of suppressing hop looper and avoid use of broad spectrum insecticides.

Technical Abstract: The hop looper, Hypena humuli Harris, is a reemergent pest of hop that often requires treatment to mitigate crop damage. In four years of field trials, plots treated with fungicides were observed to sustain less hop looper defoliation as compared to nontreated plots. Further investigation revealed that abundance of hop looper and associated defoliation were reduced when the fungicide pyraclostrobin was applied in late July to early August. Two other fungicides possessing active ingredients in the same chemical family (quinone outside inhibitor) did not reduce abundance of hop looper or its defoliation. Pyraclostrobin is efficacious against powdery mildew (caused by Podosphaera macularis (Wallr.:Fr.) U. Braun & S. Takamatsu), and the application timing evaluated in these studies corresponds with a period of juvenile susceptibility of hop cones to the disease. Use of fungicides containing pyraclostrobin at this time may have the ancillary benefit of reducing hop looper damage, potentially obviating the need for broad spectrum insecticides later in the season. Follow up studies are warranted to determine if pyraclostrobin may inhibit other lepidopteran species.

Last Modified: 12/22/2014
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