Raising fruit trees can be a challenge due to numerous pests that attack the trees and developing fruit. Fruit tree growers have a choice between chemical-based pesticides and pesticides that are derived from plant and animal sources, commonly known as organic. There are now several organic sprays for fruit trees widely available in nurseries and garden centers.
Pyrethrum is a pesticide derived from the flowers of the chrysanthemum plant. It is available in a spray or dust and is useful for all pests because it stuns or kills them on contact. The target insects must have direct contact with the spray or must be exposed within a few minutes after it is sprayed. The active ingredient in Pyrethrum, known as Pyrethrin, has a short active life and degrades within 24 hours of application. Pyrethrum should not be sprayed on blossoms or during the time of day bees are active because it is very toxic to bees.
Neem oil is derived from the Neem tree and is a light oil with insect killing and disease preventing properties. It is most useful against aphids, mealy bugs, thrips and white flies. It degrades after two to three days so it must be reapplied often.
Rotenone paralyzes or kills any insect or pest it touches, so care must be taken when using rotenone around beneficial insects such as bees. It is found naturally in the roots of a variety of tropical plants. Rotenone is often used as a spray mixed with pyrethrum. Frequent applications are necessary for complete control of damaging insects as rotenone only remains effective for up to six days when exposed to sunlight. Rotenone is very toxic to fish.
Sabadilla is a less toxic alternative than some other pesticides. It is derived from a tropical lily plant. Sabadilla is not active for very long once exposed to the environment. It must have direct contact with the pests to be effective. Sabadilla begins to degrade within 24 hours after exposure to sunlight.
Nicotine sulfate is commonly diluted to 40 percent for insect control. It is derived from the tobacco plant and is effective against aphids, leaf miners, and all types of bugs and worms. Nicotine sulfate is easily washable from fruit so it is considered a safe alternative to chemical pesticides. Nicotine sulfate begins to degrade within 24 hours after spraying and is ineffective within one week.
Bacillus thuringiensis, or Bt, is a naturally occurring bacteria that lives in soil all over the world. When the bacteria is concentrated and sprayed on plants where it is consumed by worms, caterpillars and some beetles it causes them to stop feeding and eventually die. It is considered a pesticide of low toxicity and is used up to the day of harvest, if needed. It remains viable on the plant for about 14 days and is not as toxic to bees as other organic pesticide sprays.