What Evil Lurks in YOUR Shrubbery?

BAG WORMS

"Nice looking evergreen shrubbery.  Bet ya would hate to lose it"  is what I imagine little bag worms saying to home owners. These caterpillars are a nemesis of evergreens...

This shrub, at first blush, looks OK...

...until you zero in on this thing.

This is  bag worm in its "home."

People sometimes mistake bagworms for some natural part of their evergreen, like a pine cone (they have an upside-down pine cone sort of appearance).  But they contain a destructive caterpillar, one that secretes a gooey substance and builds a "house" of sorts for itself.  Bagworms prefer juniper, arborvitae, spruce, pine, and cedar, but may also attack deciduous trees. A serious infestation can kill a tree, smaller infestations can cause death of portions of the plant,
The best organic remedy is to catch the infestation early, and cut each bag off the plant.  This may be impossible if the plant in question is a large tree.  On this case,  Bt, spinosads and pyrethrins are organic controls, but must be applied in May or June, when larvae are small and susceptible.  After they build their "home" they are less susceptible to pesticides and other controls.  In any case, cut off the bags you can reach before you spray.

Happy gardening!
And Happy St. Pat's Day, the traditional day to plant your peas!

What is BT?

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:
http://www.toxicfreenc.org/organicgardening/cabbage_worms.html

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!