Weed growth and insect occurrence as affected by irrigation regimes and weed and insect control methods.
1990
Estorninos L.E. Jr. | Moody K. | Estano D.B. | Litsinger J.A.
The experiment was conducted at the International Rice Research Institute [Los Banos, Laguna, Philippines] in the 1988 wet and 1989 dry seasons to evaluate the effect of irrigation regimes on weed growth, insect occurrence, and the effectiveness of different weed and insect control combinations. In the wet season, weed weight at 45 days after transplanting (DAT) significantly differed between irrigation regimes, insect control, and weeding treatments. Whorl maggot (Hydrellia philippina Ferino), damage at 21 DAT was significantly lower when irrigation was applied 30 DAT and was reduced by prophylactic insecticide spray. Continuous irrigation until maturity or until 30 DAT resulted in superior yield compared to the other irrigation regimes. Grain yields were lower when irrigation was done after 30 DAT. Yields were increased with prophylactic insecticide spray and when weeding was done at 21 DAT. In the dry season, weed weights at 45 DAT differed significantly between irrigation regimes and weeding treatments but were not affected by insect control methods. Number of hoppers and natural enemies were lower with a prophylactic insecticide spray and with one weeding regardless of irrigation regimes. Yields were lower when irrigation water was applied after 30 DAT and higher when there was prophylactic insecticide spray or one weeding.
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