When you spray neem oil, what is recommended dilution ratio and application rate?
Great question Brian! This is actually the source of some frustration for me, as the only products with a controlled application rate are the few EPA approved, pesticide labeled products. So there are 2 scenarios for 100% cold pressed neem:
1. You buy an EPA approved product. The directions for the product are to create a dilution with .5% to 1.1% of neem oil, with 1/3 of that amount of emulsifier such as soap. This equates to 1 to 2 pints per acre as a farmer, and about 1 tsp per quart handsprayer or 4 tsp for each gallon of water for home gardeners. This is makes the neem go a really long way compared to other products and about as affordable as any chemical control, without the toxic effects to non-target creatures. The low usage rate is possible because of the high concentration of the active chemicals and the quality control in EPA approved neems.
2. You buy a product labeled as a 'leaf shine' or 'leaf polish'. These recommend 1 oz per gallon, which is 6 tsp - 50% higher usage rate to start off with, and they aren't designed to control your pests and won't deliver anything like reliable results. There is every chance that they are actually clarified hydrophobic extract of neem - since they are not labeled as a pesticide, the EPA does not regulate the names these products call themselves - BEWARE OF SNAKE OIL!!!
I'll admit that I crusade against these products because I was ripped off by a supplier myself and don't want beginners to have a bad experience and be turned off of quality pest control that is approved for organic production.