Alfalfa Weevil Sprays

     Marsha Campbell Mathews
    Farm Advisor

    A trial conducted last spring in Yolo County compared several insecticides for Egyptian alfalfa weevil and pea aphid control and evaluated their effects on populations of beneficial insects.

    The treatments were:

    Imidan 50WP
    0.75 lb ai/A
    Furadan 4F
    0.75 lb ai/A
    Lorsban 4E
    0.75 lb ai/A
    Pounce 3.2EC
    0.15 lb ai/A
    Pounce 3.2EC+Imidan 50WP
    0.75+0.1 lb ai/A
     
    Furadan and Lorsban were the only treatments that provided better that 80% control at 21 days after treatment.  In a similar test in 1983, Guthion 3F and SevinXLR Plus gave about 80% weevil control.

    Pea aphids were common in the plots, especially at the later sampling dates.  The best pea aphid control was given by Pounce and Imidan+Pounce with intermediate control provided by Furadan.  However, Pounce was also the most disruptive to natural enemies such as lady beetles and other predators and parasites that help control aphids and other pests such as late season worms.

    This trial was conducted by Larry Godfrey, Extension Entomology Specialist, UCD and Rachel Long, Farm Advisor in Yolo County.


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    November 5, 1999