New Techniques

The Search for New Integrated Production Methods

Orchard scouting and other monitoring techniques, combined with alternate and border row spraying has resulted in a 65 percent reduction in insecticide use.

Adoption of alternative-row-middle spraying for leaf spot has resulted in a 20 percent reduction in fungicide use. Strategies currently being researched or under development, such as reduced spray programs for plum curculio and development of better spraying technology, should result in significant additional reductions in pesticide use.

Here are a few of the innovative techniques being practiced to increase safety in the orchard:

1. Using orchard scouts and trapping devices to insure that pesticide applications for cherry fruit flies are timely and precise.

   1. Growers and private consultants are trained to conduct weekly orchard inspections for cherry pests and beneficials. Simplified sampling procedures are used to monitor key insects and, based on predetermined threshold levels, detect the need for chemical treatment.

   2. Bait-lure traps are used to attract adult cherry fruit flies through a combination of their attractive color (canary/yellow) and the odor of ammonia given off by the bait. The flies are trapped in a sticky substance coating the trap. By inspecting traps at regular intervals, fruit fly presence and abundance can be judged. Traps, placed at the edge of cherry orchards, alert growers when sprays are needed. Pesticide use is reduced to a minimum by spraying only when needed. Further pesticide reduction for this pest is achieved by applying sprays only to alternate middle rows in the orchards or by treating outside rows rather than whole orchards.

2. Recent plum curculio research in tart cherries.
   This research has resulted in reductions of insecticides used to control plum curculio in tart cherries. Studies established that growers who have low populations of plum curculio can postpone insecticidal sprays for their control until 300 degree days after full bloom. Any infestation that occurs before the insecticidal application will result in the larva dropping out of the fruit before harvest. This will still allow cherry growers to produce a product that has zero larva in it at harvest time. This practice saves growers one to three insecticidal sprays, depending on the year.

3. Enhancing biological control of mites.
   Weed-free zones under the tree during early spring, drought, and the use of pyrethroid insecticides are conditions that may contribute to damaging populations of phytophagous (pest) mites.

   1. Conserving natural populations of beneficial mites is a critical part of effective integrated mite management. Habitat for entomophagous (predacious) mites (Amblyseius fallacis and Zetzallia mali are the most prevalent in Michigan) can be improved by the presence of weeds under the trees during fall and early spring. Some growers intentionally leave some weeds under the trees to enhance biological control of mites. Late spring applications of herbicides are preferred to fall applications. Scouting determines the need for additional control measures.

   2. Predacious mites have developed resistance to organophosphate insecticides. When pyrethroid insecticides are used to control insect pests, the populations of predacious mites plummet, negating efforts at biological control of mites and often requiring applications of miticide. This stresses the importance of currently maintaining organophosphates as chemical control tools. In addition they are very effective at controlling fruit fly and curculio using the strategies outlined above.
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