Author
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BRUCK, DENNY |
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Submitted to: Compendium on Hop Diseases and Pests
Publication Type: Book / Chapter Publication Acceptance Date: 6/16/2006 Publication Date: 5/1/2009 Citation: Bruck, D.J. 2009. Root Weevils. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H. editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p.93. Interpretive Summary: Technical Abstract: Numerous species of root weevil, Otiorhynchus spp. (Coleoptera: Curculionidae), infest hop. The black vine weevil, O. sulcatus (F.), is the dominant species infesting hop followed by the strawberry root weevil, O. ovatus (L.), rough strawberry root weevil, O. rugosostriatus Goeze, and O. meridionalis (Gyllenhall). While the habits and characteristics of each weevil species are unique, the general life history for all species is similar. Root weevils overwinter in the soil, primarily as last instars, although a small percentage of the population can survive the winter in the soil as adults (5-10%). Pupation begins in mid-April and adult emergence is generally complete by mid-late May. Oviposition by newly eclosed adults begins in late June continuing thru September. Overwintered adults can begin to oviposit by late May and continue until early July. Larvae are the most damaging stage. Severe larval infestations can significantly shorten the useful life of a hop yard through feeding on rhizomes, roots and crowns of plants. Root damage by larval feeding results in reduced nutrient uptake and plant growth as well as water stress. Plantings heavily infested with root weevil larvae can drop leaves prematurely and may require that individual plants or entire fields be removed from production. Larval feeding not only reduces plant vigor but can serve as an entrance point for soil-borne plant pathogens. Preovipositional adults are the life stage most actively managed in hops with nighttime insecticide applications. Larval infestations can also be effectively managed with applications of entomopathogenic nematodes and fungi. |
