Dormant oil spray is a horticultural spray that is used on wood plants, such as fruit trees, as a pest preventative. Dormant refers to the time of year that it is applied more than the actual type of spray. The spray is used to prevent pests and disease during the growing season. Dormant oil is available as both organic and nonorganic treatments. Natural and organic methods of controlling pests and disease are available. Diatomaceous earth (DE), nematodes, neem oil and crop rotation are a few examples of alternatives to dormant oil spray.
Diatomaceous earth is made from microscopic single-celled plants. Diatoms have existed for hundreds of thousands of years. Their fossilized remains are mined and processed into a fine powder. DE has very fine, razor-sharp spines that cut through the tough exoskeleton of insects causing vital fluids to leak out. The insects die from dehydration. Diatomaceous earth is not effective against plant diseases.
Beneficial nematodes are an effective alternative to dormant oil spray. Beneficial nematodes are microscopic worms that thrive in moist soil. There are over 20,000 species of nematodes, a handful of which are considered pests and will not be affected by beneficial nematodes. Nematodes enter the host body, usually the larvae stage of common pests, and infect them with a bacteria that kills, physically alters or renders the larvae sterile. They are considered parasites because of their need for a host body. Beneficial nematodes are not effective against plant diseases.
Neem oil is a plant extract from the neem plant. The leaves and seeds are harvested and then the oil is extracted. It acts as antibacterial and antifungal agents. It stunts the growth of many weeds and leaves insects unable to reproduce. As an alternative to dormant oil spray, neem oil is effective because of its ability to control both pests and diseases.
Rotating crops and allowing field to remain fallow (unused) helps to control pests and disease. Most pests require that the same food source be available year after year. Removing their food source eliminates the pests in most fields. Allowing a field to remain fallow has a similar affect on bacteria and fungi. With no reliable source of nutrients necessary to procreate, bacteria and fungi presence will diminish in most soils.