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|Controlling Aphids on Cole Crops|
|Written by Ann Shepphird|
We recently received the following question: I am a home vegetable/herb gardener in San Diego. I have only been growing for three years, so I am still learning. I tried to grow cauliflower, broccoli and cabbage last cool season and they looked so wonderful. I harvested them and got ready to cook, and they were FULL of aphids! What a disappointment. I spoke to my local nursery, Walter Anderson, and they advised me to “just give up growing cole crops organically.” Well, I just refuse to believe that! Can you help me with some tips on controlling aphids on my cole crops here in San Diego? I'm in Sunset climate zone 23. Thanks, Jennifer Boles
For the answer, we contacted Nick Sakovich and here are this thoughts.
I wouldn't give up. There are some things to do: The two main organic insecticides you can use are horticultural oils, including neem oil, and soap sprays. These will do a decent job. Spraying when you first see the problem, i.e. when the aphid population is low, is best. Other organic insecticides that can be used -- but are more toxic to humans and beneficial insects -- are the pyrethrins (derived from the chrysanthemum flower) and rotenone. One should always read the labels to make sure the product is registered to be applied to that particular crop. When spraying with insecticides, repeat applications are needed since the sprays usually do not control all stages of the insect’s life cycle. Labels usually recommend at least two applications at 5 - 7 days apart.
Spraying with a heavy spray of water offers some control. Most of the aphids removed will not return.
The University of California, San Diego, Cooperative Extension always has good answers on a variety of horticultural problems.
The University of California also runs a statewide program that matches gardeners with a master gardener in their area available to answer questions. The list can be found at the University of California, Davis, Statewide Master Gardener Program website.