The Q&A Archives: Help With Pest Control

Question: I have approximately 60 sweetbroom plants lining my fence that are being ravaged by caterpillars. The plants have lost all leaves and flowers and are very brown.

I had a similar problem last year and used both pesticidal oil and pesticidal soap (alternating between oil and soap each week). Last year, after a few weeks of spraying, that seemed to do the trick. This year it is not working and I'm afraid of losing all of the plants. I tried malathion (yesterday) but that those little buggers are still there and chomping away at the sweet brooms. Any suggestions? Thank you for your help!

Answer: Brooms are on the noxious weed lists of most counties along the west coast. While the invasive brooms are not necessarily the ones gardeners choose for their landscapes, botanically speaking, brooms are brooms. There has been an attempt to control the spread of invasive brooms by introducing an insect called the twig mining moth (Leucoptera spartifoliella). These fellas (and their caterpillar youngsters) love to feed on brooms of all kinds. Before you make further attempts to kill off the critters, why not take a specimen to your local cooperative extension office for identification? (Phone 619-694-2845) If it's the biocontrol insect, the extension office would like to document it. If not, they can recommend control measures for them. Good luck with your brooms!

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