Pesticides for Fruit Trees
Insect pests can destroy a fruit crop or kill a fruit tree entirely. Their life cycle continues throughout the year, even during the winter. For effective insect control, a regular spraying program must be put in place to control insects. Because most fruit trees are hybrid plants susceptible to pests, knowing which pests infect fruit trees, their life cycle, and the correct pesticides to use, will help you have a productive and bountiful season.
Spinosad is made from the Saccharopolyspora spinosaus bacteria and is derived from a special fermentation process. It has a residual period for up to four weeks and is used to control beetles, worms and thrips. Some insects are killed on contact, while most need to consume a part of the plant containing Spinosad for control, according to Texas Cooperative Extension.
Dormant oil is sprayed on fruit trees during the dormant period when flower and leaf buds are just beginning to swell in the spring. It smothers insect pests that overwinter on trees waiting for spring bloom and fruit production. It not only effectively controls scale and mites, but kills the eggs of insects that were laid on the tree in the fall. Most fruit tree pests can be controlled with one application of dormant oil applied at the right time of year.
Malathion is a chemical pesticide used for insect control any time of the year because it kills all insects on contact. However, the best time to spray Malathion is before the eggs of the offending pest are laid. That is why it is a good idea to know the life cycle of the fruit tree pest you are trying to control. It can mean the difference between one application per season or several. Malathion kills bees and other beneficial insects, so it must be used after the flowers on the fruit trees drop and fruit begins to form.
Imidacloprid kills most insects upon contact with the pesticide. It also works as a systemic insecticide. A systemic insecticide enters the plant's vascular system and kills sucking and feeding insects by interfering with their nervous systems.
Carbaryl is a pesticide available in a spray of dust. It kills all insects, including beneficial insects, on contact. It is not effective in killing borers and some beetles. It must be reapplied every seven to 10 days for control. However, it is best to use Carbaryl to control a specific insect problem rather than using it for general insect control over the entire season, so beneficial insects are not affected.
Bacillus thuringiensis, or Bt, is an organic pesticide used for controlling worms and caterpillars. It is not effective against other types of pests. However, there is a strain of Bt known as Bt Kurstaki, used for controlling potato beetles. It is made from a naturally occurring bacteria and kills by interfering with the worm's or beetle's digestive system. It has a short effective life, and must be reapplied every four to seven days. It does not harm beneficial insects.
- University of Rhode Island Landscape Horticultural Program: Home Tree and Small Fruit Pest Management Guide
- University of Missouri Extension: Fruit Spray Schedules for the Homeowner
- New Mexico State University: Fruit Tree Pest Control
- Bexar County Cooperative Extension: Spinosad: An Insecticide to Make Organic Gardeners Smile