Delayed flood for management of rice water weevil (Coleoptera: Curculionidae)

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Draining and reestablishment of permanent flood has been used to prevent injury caused by larvae of the rice water weevil, Lissorhoptrus orjzophilus Kuschel. However, there are negative effects associated with this management practice such as loss of weed control and nitrogen, which necessitate the reapplication of herbicide and nitrogen followed by the reestablishment of permanent flood. An alternative to draining rice, Oryza sativa L., fields for rice water weevil management is to simply delay the establishment of the permanent flood. Delayed flood avoids problems associated with draining and reflooding fields. The primary objective of this study was to evaluate the efficacy of delayed flood for rice water weevil management and its impact on weed management using a herbicide resistant rice line. Use of herbicide resistant rice lines enables the application of delayed flood for rice water weevil management because of an increased spectrum of herbicidal activity against weeds. Delaying flood significantly reduced and delayed rice water weevil larval populations, providing an alternative cultural practice for rice water weevil management. Significantly improved management of noxious weeds was also observed without additional herbicide inputs. We anticipate that the yield gain from rice water weevil management without an insecticide application and with reduced (or altered) herbicide applications will be such that the potential yield loss from delayed flooding (as a result of possible physiological stress on the rice plant) will be offset.

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Environmental Entomology

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