Influence of Nitrogen Fertilizer Rate on Hop Looper

Hop looper, Hypena humuli Harris, can cause substantial defoliation and crop damage by feeding on hop leaves and cones. A 4-yr field study conducted in western Oregon evaluated the abundance of hop looper larvae and associated defoliation of leaves on plants fertilized with nitrogen rates ranging fr...

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Bibliographic Details
Published in:Journal of economic entomology 2018-09, Vol.111 (5), p.2499-2502
Main Authors: Iskra, A. E, Woods, J. L, Gent, D. H
Format: Article
Language:English
Subjects:
Abundance
Agricultural chemicals
Ammonia
Annual variations
Cones
Crop damage
Data processing
Defoliation
fertilizer
Fertilizers
Humulus lupulus
Hypena humili
Hypena humuli
integrated pest management
Larvae
Leaves
Nitrogen
Nitrogen fertilizers
Plants (Organisms)
SHORT COMMUNICATION
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Summary:Hop looper, Hypena humuli Harris, can cause substantial defoliation and crop damage by feeding on hop leaves and cones. A 4-yr field study conducted in western Oregon evaluated the abundance of hop looper larvae and associated defoliation of leaves on plants fertilized with nitrogen rates ranging from 44.8 to 269 kg/ha. There was annual variation in abundance of hop looper and defoliation, with a tendency for increasing nitrogen rate to increase both abundance of hop looper and defoliation. A mixed model analysis with data combined from 2014 to 2017 found that abundance of hop looper was linearly related to nitrogen fertilizer rate, with a 2.5 increase in hop looper-days per kilogram of nitrogen fertilizer applied. Similarly, based on data from 2015 to 2017, defoliation associated with hop looper increased 0.031 percent with each kilogram of nitrogen fertilizer applied.Therefore, avoiding unduly high rates of nitrogen fertilizer may reduce the abundance and defoliation caused by hop looper. Further studies are needed to understand the mechanisms associated with nitrogen stimulation of hop looper.
ISSN:0022-0493
1938-291X
DOI:10.1093/jee/toy229