Grape-Spotted-wing drosophila

Drosophila suzukii

For pest description, crop damage, biology, life history, sampling and cultural management

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This insect has limited known commercial impact on wine grapes in Oregon and Washington to date. Adult SWD can be found feeding on damaged or cracked berries directly before harvest. Wine grapes in Western production regions are more susceptible to SWD impact, especially when the berry surface area is cracked due to insect damage, bird damage or Botrytis. Research has shown that drosophilid flies vectors spoilage bacteria under these conditions, thereby influencing fruit quality. Growers should take necessary steps to minimize berry damage. Identify blocks impacted by vectoring of spoilage bacteria spread by SWD. Remove or harvest affected berries. Virtually no fully intact berries collected in vineyard studies have SWD eggs or larvae developing in them. A very small portion of damaged berries may contain eggs and an even smaller portion of eggs manages to develop to adulthood. However, research continues to determine seasonal differences.

Management-chemical control: HOME USE

  • spinosad-This product generally provides a relatively high level of adult control, and 5-7 days residual activity, depending on conditions. Under rainy conditions, this residual period may be shorter. Some formulations are OMRI-listed for organic use. Group 5 insecticide.

Management-chemical control: COMMERCIAL USE

Note: Treatment with pesticides is generally not necessary for this pest. However, if infestations and damage are noticed, the following insecticides can be used to manage this pest.

Laboratory tests and field experiments indicate that many of the pesticides registered for use in grapes are effective in controlling the adult SWD. Although SWD may not be listed on a label, it is legal to use for SWD management. The products listed below target the adult stage of SWD. The relative level of control indicated for each pesticide was determined under both laboratory and field conditions.

  • malathion (Malathion 5EC) at 2.0 lb ai/a. PHI 3 day. Toxic to bees and most aquatic invertebrates, and carry the risk of mammalian toxicity. Do not apply when bees are foraging. They provide 100% mortality of SWD, and 7 to 10 days residual control in the field. Under rainy conditions this residual period may be shorter. Group 1B insecticide. This is an organophosphate insecticide.
  • pyrethrin (Pyganic and other brands)-Consult label for rate and use directions. Toxic to bees; do not apply when bees are foraging. Highly toxic to fish. Provides 80% control of SWD but has no residual activity. Some formulations are OMRI-listed for organic use. Group 3A insecticide.
  • spinetoram (Delegate WG) at 0.047 to 0.078 lb ai/a. PHI 7 days. Retreatment interval 4 days. Do make more than 5 applications per season (not to exceed 0.305 lb ai/a per year). Toxic to bees for three hours following treatment. Do not apply when bees are foraging. May provide 100% mortality of SWD, and 5 to 7 days residual control in the field. Under rainy conditions this residual period may be shorter. Group 5 insecticide.
  • spinosad (Success or Entrust) at 0.0625 to 0.125 lb ai/a. PHI 7 days. See label for use in grape for OR, WA and ID. Entrust is OMRI-listed for organic use. Toxic to bees for three hours following treatment. Do not apply when bees are foraging. May achieve 100% mortality of SWD, and provide 5 to 7 days residual control in the field. Under rainy conditions this residual period may be shorter. The bait formulation of spinosad (GF-120) is not effective against SWD. Group 5 insecticide. Do not make more than 2 consecutive applications of Group 5 insecticides. Do not apply more than 0.45 lb ai/a per season.