Central Virginia Organic Gardener

"And 'tis my faith that every flower enjoys the air it breathes." - William Wordsworth, 1798

Sunday, February 3, 2013

What is BT?


Sometimes people ask me for what product to use to stop some sort of pest.  I do not use a lot of these organic pesticides, preferring barriers, hand picking or squashing (not for the squeamish), blasting them off with a spray of water, growing resistant varieties, and/or rotating crops (this last practice reduces recurrence of infestations).  I also try to grow plants that attract beneficial bugs.

There is one organic product, technically a pesticide as it kills pests, that I do use and am experimenting with: BT, also BTk.  What is BT?  It is Bacillus thuringiensis (Bt), a bacteria that produces crystals toxic to susceptible insects, almost all caterpillars, those pests that like to munch their way through your broccoli, cabbage, squash and other plants.  (Btk is BT kurstaki, a variant that works best in most garden applications).  These crystals are toxic to nothing else, do not harm people, pets, bees or birds.  In order to die from the toxin, then caterpillar must eat it, and then the toxin causes it to stop feeding.  It dies in a day (unlike chemical pesticides which kill on contact).  Toxic Free NC has a page dedicated to one of these BT susceptible pests, the cabbage worm, at:

If you want to buy this product, you cannot just ask for "BT" (I have done just this and been given blank stares).  You have to look at the labels of "organic caterpillar killer" to see if they contain  BT (they probably do).  Brand names are Dipel and Thuricide.

So if you don't like hand picking, or do not have the flexibility to be vigilant abut this (twice a day with big infestations) try BT.

Happy Gardening!
Oh, and Happy Belated Groundhogs' Day!  Mechanicsville Mike says spring is just around the corner!


Anita said...

Occasionally, I do wonder what the long term effects of the mucho amount of pesticides we use.

How did I miss Punxsutawney Phil yesterday? I didn't even give him a thought. Glad you have a good report from Mechanicsville Mike.

Anonymous said...

Once I asked for BTk (verbally) at a Home Depot around the time that some primetime television show reported on the search for a serial killer whose tagline was BTK (can be googled). Agreed: best to ask for organic caterpillar pesticide!