Tuesday, October 2, 2007

Codling Moths in Your Herbs

I've found that the people who typically know about codling moths are those with fruit orchards (since the larvae are the stereotypical "apple worm"). This is after I've asked I don't know how many (vegetable) growers, who look at me as if I have two heads when I mention the pests! (For a photo and some information, you can look here: http://crawford.tardigrade.net/bugs/BugofMonth33.html)

This summer, I've had an unusually difficult time with them in the greenhouses. I didn't even realize what they were. All of a sudden, my thyme beds looked like they had clumps of mysterious webbing throughout, and (it seemed) within a few weeks, regardless of my efforts to eliminate the webs and the larvae (little worms), I'd lost a few beds. They progressed into quite a few other beds -- mostly the ones with tightly clumped leaves/plants, like mints, oregano, and rosemary. What a nightmare! Cutting back the plants didn't do much -- in fact, it sometimes seemed to make matters worse. The parent moths -- small, mottled, brown things -- were all over, and it took a bit of detective work to find out what they were, and that it was their larvae eating my plants!

So during my investigation, I first looked at biological controls. There are some insects that attack the larvae, and maybe long term, I will consider them, but I needed something fast, before they ate and killed everything! I found a broad-scale OMRI-approved (organic) insecticide -- Agroneem, with a base from the oil of the neem tree (http://www.agrologistic.com/content/agriculture/agriculture.pdf) -- that was supposed to control the buggers. And after several applications over a period of weeks, I noticed a marked improvement (though they're still not completely gone). However, I'm still not satisfied -- I hate having to apply anything like that regularly (even though it's natural and completely safe for humans) -- so I've been considering another method. Some fruit growers have had success using pheromones, which disrupt the mating cycle, and the process includes putting out bait traps in high concentrations to lure the males, confuse them, and prevent them from mating with the females. I've also read that nasturtium is a natural companion plant to deter the moth, and though putting them throughout the greenhouses would be a bit difficult, I might try it!

Anyway, I thought I'd share this with you, because I'd bet that many of you have had this problem in your garden, in one way or the other, and never understood why it was you lost some herbs from the mysterious webbing. I'll try to take some photos and post them, so you can get an idea of what I'm talking about...

I'd imagine this been particularly cumbersome in my situation because of the protected greenhouse environment, though I did see some of the problem (though not as bad) in my outside beds, too. I'm open to any other suggestions! Let me know your thoughts, and if you've had similar problems. Photos to come!

No comments: