Noting the date of the book, Potassium nitrate (saltpeter) isn't necessary and has associated risks.

If cabbage loopers are a problem for you - not that they congregate in gangs as the author implies ;) - then Bt ) bacillus thuringiensis label Dipel) is the accepted, effective, common, and organically accepted solution.

Dave

"...associated risks."

Such as?

Jim

"...associated risks."

Potassium nitrate is a Class 5 rated hazardous material, highly flamable.

Per its MSDS: STRONG OXIDIZER. CONTACT WITH OTHER MATERIAL MAY CAUSE FIRE. HARMFUL IF SWALLOWED, INHALED OR ABSORBED THROUGH SKIN. CAUSES IRRITATION TO SKIN, EYES AND RESPIRATORY TRACT.

Wear appropriate protective clothing to prevent contact with skin and eyes. Wear a self-contained breathing apparatus (SCBA) to prevent contact with thermal decomposition products. Containers may explode in the heat of a fire. Vapors may be heavier than air. They can spread along the ground and collect in low or confined areas. May decompose explosively when heated or involved in a fire. May accelerate burning if involved in a fire. May explode from heat or contamination.

So it's use requires wearing protective equipment and special storage conditions. Plus there are reported cases of nitrates converting to toxic nitrites.

Likely they weren't aware of all that back in 1917. ;)

Dave

Here is a link that might be useful: MSDS - Potassium Nitrate

Apparently they weren't aware of it in the 1940's either, when potassium nitrate was one of the reagents supplied with my Gilbert chemistry set. Things have changed. Potassium nitrate hasn't changed but attitudes have. The chemistry set didn't say anything about wearing SCBA gear. Chemistry sets aren't sold anymore. Some of my friends, all of whom had Gilbert chemistry sets, went on to become doctors and chemists. I truly believe their chemistry sets were the seeds of their interest in those professions.

Jim

If they're anything like the cabbage worms in my yard, they'd have a chance to gather again by the next morning.

The first (and last) time I grew kale I picked about 25 worms off the plants every day. (and that was only off of a few kale plants) They completely decimated it.

If I try growing it again, I'm going to use rowcovers.

Yet another example of the miracle that we all survived our childhood, right Jim? If playing in the dirt, the mud pies, barn cats, and rolling in the leaf piles didn't get us the chemistry kit should have. ;)

Dave

All of that and more, Dave. We used to like the taste of the little oxalis plants that grew around our homes, the ones with the little yellow flowers. They were intensely sour because of the oxalic acid in them. In those days we got away with it, but today I'm sure it would kill a kid to eat that toxic stuff.

Jim

Saltpeter + sulphur + charcoal = gunpowder

Separately not a problem. Combine it and you can get great control of the loopers (and cabbages) and they'll haul you away to boot.

Sevin, Malathion, or Diazinon if you still have any also work quite well on loopers, however in my dry climate, I think Bt provides control for a longer period.

Row covers work. I've been using them for years on all my cole crops--cabbages, broccoli, kale, Asian cole crops, etc. Not a single worm. They're easy, cheap, resusable, effective, and safe.

Thanks for all of the info on saltpeter! I've heard that hardware stores around here used to carry dynamite...now THAT might just take care of my cabbage loopers! But alas, I think you need permits, licenses, and such to use it. Just when you find something effective, they take it off the shelves...

Thank you didgdirt & laceyvail... I will try the BT & row cover approach since dynamite is out of the question in my locale!

Jim,
The oxalis you speak of is Oxalis stricta which is a wildflower (or weed) here in Kansas and Missouri. When I was a kid, we used to eat them too and the kids used to call them sour pickles. I've read that back East they are referred to as "sours". Interesting how much of this plant we ate and never suffered for it although references indicate that occasional and limited use of the plant is not harmful. Here's a link.
http://www.missouriplants.com/Yellowalt/Oxalis_stricta_page.html

Sorry for the interruption. Floating row covers are inexpensive and invaluable in preventing cabbage worms.

Ya I kinda miss the dynomite I never used it on cabbage worms but it sure took care of stumps and rocks LOL. Oh wait that was 60% TNT we used the most. We could rattle windows a mile away if we got the charge right!

Curt :O

Shotguns or dynamite for cabbage loopers...very rarely do I actually "LOL", but this was one of those times.

That image makes me think of Bugs Bunny cartoons. LOL

Jim

I have yet to try it but, Spinosad may work well as an alternative to Bt. Bt has worked very well for me for many years but the possibility of developing resistance has me thinking of trying out Spinosad this year. If Spinosad works well, I'll use it this year early and rotate it with Bt thereafter.

I found, much to my surprise, an 8 oz. bottle under the Fertilome label at Ace Hardware a month ago.

Michael