Agriculture Reference
In-Depth Information
and syrphid flies, and do not usually harm bumblebees. They have a very low
level of toxicity to mammals and birds, although the soaps are irritating to
the skin and eyes. Ammonium-based soaps are sometimes touted as being
repellent to deer and rabbits, but do not count on them to protect your trees
or bushes against these pests.
Although pesticidal soaps are very useful, they have definite limitations
and must be used as part of a system that integrates other pest controls.
Their effectiveness is rather low, perhaps 40 to 50 percent, against small,
soft-bodied pests. Soaps kill only pests that are contacted directly by the
soap solution and in relatively large amounts. Once the soap solution dries on
the plant, it has no effect on pests. You need to spray thoroughly to ensure
the upper and lower surfaces of branches, leaves, and fruits are covered. This
means using large amounts of soap solution, usually at about 2 percent con-
centrations.
Hard water makes soaps ineffective. If your water is hard, you may need
to treat the water to soften it. Some products are available that can be added
directly to the water to improve insecticidal soap effectiveness. Follow label
directions carefully. Soap sprays work best when they dry slowly, such as on
cool, cloudy days, or in the evening.
The soaps can be phytotoxic if used too frequently or at concentrations
that are too great. Similar soap products have been developed as organic
erally tolerate pesticidal soap applications well, but fruit can be damaged if
large amounts of spray collect at the bottoms of fruits. Soaps are also highly
unpalatable and have offensive odors. Be sure your fruits are free of soap
residue before using or marketing them.
Microbial Insecticides
Microbial insecticides include assorted strains of
Bacillus thuringiensis
and
Beauveria bassiana
.
