Gardening with Allen: Organic Pesticides Control Many Insects
To control root maggots, spray the soil around radish plants and other root crops as soon as the seedlings emerge from the soil. It can also be sprayed on the seeds before they are covered with soil.
To avoid deworming apples, start spraying the fruit as soon as it reaches the size of the tip of a little finger and repeat at two week intervals until early August.
Spinosad will also control insects on roses and other woody ornamentals, including borers and caterpillars on trees.
The word “spinosad” may not appear on the primary label. You may need to check the active ingredient labels to find it. It will most likely be available at full service nurseries and garden stores.
Bacillus thuringiensis (Thuricide) is a biological pesticide particularly effective on caterpillars. It is very effective in controlling cabbage worm which feeds on cabbage and related vegetables like broccoli and cauliflower.
Neem oil is another organic pesticide. Derived from the neem tree, it is effective in controlling major insects as well as a number of leaf diseases. This is my favorite pesticide for roses because it controls both insects and diseases. Spray roses every two weeks to prevent black spots and other leaf diseases.
Other organic fungicides for plant disease control include lime sulfur, copper, and horticultural oils.