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Page 2 of 3
Aphid Control With Benefits
Finding An Alternative
UC researchers (both campus and county based), supported by public (UC SAREP, UC IPM, and CA DPR) and private (local growers and California Dried Plum Board) funds, have worked on alternatives for prune aphid control since the mid 1990's. Their goal was clear: Can pesticide type, timing, and/or rate be adjusted both to control aphids and reduce the risk of pesticide runoff?
The answer is yes, with many teams of researchers contributing.
Key, basic work by Dr. Nick Mills and his lab at UC-Berkeley showed that adult plum aphids move back into prune orchards from their summer hosts by mid-October at the earliest.Dr. Frank Zalom and his lab at UC-Davis also showed that diazinon runoff is significantly reduced when the pesticide is sprayed during dry periods between storms, when orchard soils are less saturated and more able to absorb rainwater (and pesticides which are then broken down by soil microorganisms). Their results suggest that the potential for runoff is least early in the dormant season, before rain saturates soils and increases runoff potential.
Leaf curl plum aphid (left) and mealy plum aphid (lower right) are two of the biggest pests facing California prune growers. Recent University of California research has led to new ways for growers to control these insects, while reducing runoff at the same time.
Photos by Jack Kelly Clark, courtesy UC Statewide IPM Program
UC farm advisers showed that reduced rates of diazinon (1 to 2 pints per acre) or Asana (esfenvalerate, DuPont Crop Protection at 1to 5 ounces per acre will control prune aphids during a traditional dormant timing (February). Spraying less material means there is less pesticide released into the environment and available to run off if a big storm hits. Note: these reduced rates are effective against aphids. If other pests like peach twig borer or San Jose scale are particular problems in a given orchard, the higher label rates may be needed.
Recently, UC farm advisers have shown that labeled pesticides can give effective prune aphid control if applied either in the fall or just before bloom (see Aphid Control Trials), and may give growers a good option to traditional dormant treatments.
If you have questions about any of the research results presented in this article, please contact University of California Cooperative Extension. Contact information is on the Web at
fruitsandnuts.ucdavis.edu/crops/prune.shtml
Information for this article was provided by UC Cooperative Extension's Franz Niederholzer, Bill Krueger, Rich Buchner, Carolyn Pickel, Bill Olson, Frank Zalom, and Nick Mills. E-mail questions or comments about this article to afg.edit@meistermedia.com.
from AMERICAN/WESTERN FRUIT GROWER - February 2005
Next - Aphid Control Trials - Page 3 of 3
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