I have also used rubbing alcohol (isopropyl alcohol) on spider mites with very good results.I used it full strength, but probably half strength is fine.It did not burn the leaves at all.Dish detergent knocked them down, but alcohol eliminated them.I spray it on or put it on a cloth and wipe the leaves.The wiping also eliminates any residue on the leaves For powdery mildew and black spot I have used baking soda, one tablespoon in a quart of slightly warm water, then added about a teaspoon of the spreader that I bought to use with copper for my peach trees.I'm sorry, I can't remember the name.It has also been recommended to use a horticultural oil such as Sunspray as the spreader.This mixture worked better than any fungicide I had tried on my roses.It also was good for rust.I tried it on rust on my oxalis, but it burned the leaves, but even horticultural soap burns oxalis leaves Diana Telos Rare Bulbs diana chapman mailto:rarebulbs@earthlink.net