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Title: DELAYED FLOOD FOR MANAGEMENT OF RICE WATER WEEVIL,LISSORHOPTRUS ORYZOPHILUS (KUSCHEL)

Author
item Rice, William
item CROUGHAN, THOMAS - LOUSIANAN STATE UNIV
item RING, D - LOUISIANA STATE UNIV
item MUEGGE, M - LA AGRIC EXT SERV
item STOUT, M - LOUISIANA STATE UNIV

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Traditional methods for rice water weevil, Lissorhoptrus oyrzophilus (Kuschel), control are based on the use of chemical insecticides. However, concerns over the environmental effects of carbofuran, especially its toxicity to avian species, have led the EPA to revoke the registration of carbofuran for RWW control. Results of this paper suggest that delaying the epermanent flood that is normally applied to rice culture can significantly reduce and delay RWW larvae densities. This effectively prevents economic injury to rice plants caused by the RWW larvae. It should now be possible to eliminate or greatly reduce the amount of chemical insecticides required to prevent economic injury to rice plants caused by the RWW. This change in cultural practice is dependent on effective control of noxious weeds.

Technical Abstract: Cultural practices employing draining and reestablishment of permanent flood have been used to prevent injury caused by larvae of the rice water weevil, Lissorhoptrus oyrzophilus (Kuschel). However, there are negative effects associated with this management regime such as loss of weed control and nitrogen (due to oxidation and loss of a gas) which necessitates the reapplication of herbicide and nitrogen followed by the reestablishment of permanent flood. An alternative to draining rice fields for the control of te rice water weevil (RWW) 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 RWW control and its impact on weed control using a herbicide resistant rice line. Use of herbicide resistant lines enables the application of delayed flood for RWW control due to an increased spectrum of herbicidal activity against weeds. Delaying flood significantly reduced and delayed RWW larval populations, providing an alternative cultural practice for RWW control. Significant control of noxious weeds was also observed without additional herbicide inputs. We anticipate that the yield gain from control of the RWW without an insecticide application and with reduced (or altered) herbicide applications will be such that the potential yield loss from delayed flooding (due to possible physiological stress on the rice plant) will be offset.