Re: Brussels sprouts, holes in the leaves… help.

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  • Tue, Apr 28, 2009 - 04:54pm

    Peak Prosperity Admin

    Peak Prosperity Admin

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    Re: Brussels sprouts, holes in the leaves… help.



[quote=cat233]Thank you c1oudfire and Plickety,

Upon investigation this morning, I found the culprit.  I tiny worm about .25 of an inch long.  Lime green and yellow…. Any thoughts?


Without seeing it, I’d say it could be cabbage loopers.  The good news is that Bt works on all "worms" (small caterpillars, actually).  Apply the Bt ASAP, as it takes a couple of days to work.  It disables the gut of the caterpillars so that they starve to death.  For those who are sensitive, I’m sorry to be so graphic. . . .


If you don’t want to use Bt, you can also purchase and release trichogramma wasps to destroy any remaining unhatched eggs. Pheromone lure traps can keep the adults from breeding and laying the eggs in the first place.


Bt is so effective, there’s no reason to use conventional pesticides and exposing yourselves to their inherent risks.  Bt is nonspecific and will work on any caterpillar that is young enough that the gut may be penetrated by the bacteria.  However, it may kill the caterpillars of harmless butterflies, too.  If it bothers you to use the Bt, then the trichogramma wasps are another option, but they won’t be effective  against hatched caterpillars, which are your current problem.  Parasitic wasps, in general, are trickier and less reliable to use than Bt.  They are very host specific, so that if you don’t match the parasitic wasp to its specific preferred host, it won’t work at all.  If all of the above seem less than ideal, then floating row covers are the way to go, next year.