I conducted an interview with Dr. Linda Chalker Scott, an urban horticulturist at Washington State University, on what might be the best organic method to help me get a better yield from my squash plants. Bacillus thuringeinsis is an organic solution I've heard of so I wanted to get her opinion on using it on squash. She answers that question and many others on my blog.

What's been your experience using Bacillus thuringeinsis?

I tried spraying the plants down, but I think I discovered the borers too late. It might have helped with later infestations, but I don't know. I used Thuricide mixed 4T to a gallon. Wear goggles when you spray it! It irritates the eyes.

I also injected BT directly into the infected vines. I mixed it at 1 teaspoon BT to 1 cup water and injected 1ml at each spot. I used an 18g needle and 3ml syringe. They are available from any farm and ranch/livestock catalog or feed store. I also tried injecting predatory nematodes into the zucchini vines. I mixed it up as instructed, transferred to the sharp needle (the one it comes with is useless) and injected .5 to 1 ml per spot. THIS IS IMPORTANT: wear safety glasses/goggles when injecting. The squash vines will clog the needle occasionally and, when that happens, the needle comes away from the syringe and the bt or nematodes shoot back directly into your face. It is not any fun flushing your eyes out for 20 minutes and then frantically searching the internet to find out if the nematodes are about to eat your eyes (they won't, there have been accidents at the facilities that grow the nematodes and everyone is fine). Also, do not dispose of the needles directly into the trash. Drug stores sell containers for used needles (for insulin needles).

Something worked, but I don't know if the nematodes or BT did the job. It definitely saved my African and Delica winter squash. Unfortunately, some of my squash were too far gone to recover.

I'm going to try it again next year and attempt row covers for the time period when I had problems.

Bellatrix