Fruits such as caneberries, blueberries, and grapes are at highest risk and in New Jersey we have found infested blueberries and now caneberries. We are currently trying to identify the risk for peaches and critical periods for grapes.
SWD is a small (1/10”) fruit fly that looks similar to vinegar flies. Unlike native fruit flies, SWD attacks ripening fruit, especially thin-skinned fruit. Females use a serrated ovipositor to saw through the fruit skin to lay their eggs. The larvae (maggots) develop inside the fruit causing collapse. Fruits such as caneberries, blueberries, and grapes are at highest risk and in New Jersey we have found infested blueberries and now caneberries. We are currently trying to identify the risk for peaches and critical periods for grapes.
It is important to implement IPM programs to minimize the impact of SWD in NJ. The first step is to monitor the population with apple cider vinegar traps to determine if SWD is present. We recommend a conservative approach for management; if you have ripening fruit and SWD is present in vinegar traps, growers should: 1) increase monitoring efforts, 2) implement cultural control and maintain insecticide applications through harvest.
All infested fruit and dropped fruit should be collected and disposed of. Research in Oregon suggests placing fruit in a plastic bag in direct sun to kill larvae – composting and burying are ineffective measures. There are some reports that significantly increasing the number of vinegar traps may reduce infected fruit but this has not been studied thoroughly.
IPM programs for SWD are being developed although some insecticides already registered for caneberries will provide protection against SWD, specifically the pyrethroids, spinosads, and organophosphates. However, SWD has multiple generations per year and a very quick development time, therefore it is highly important to rotate insecticide chemistries with different modes of action. Due to the quick development time it is also important to be mindful of the PHI and the maximum allowable for each product. Malathion, Delegate and Mustang or Mustang Max have a 1 day PHI in caneberries and are recommended for control (see table). These compounds should provide 7 days of residual activity, although this will be decreased in hot weather for pyrethroids including Mustang Max. Similarly for organic growers, insecticide recommendations are Entrust, Pyganic and Azera. Attaining proper spray coverage of the canopy is important as the flies rest in shaded areas.
Always Read and Follow Label Instructions!
|Trade Name||Label Rate for Caneberries||Max. allowable/Season|
|Malathion 5EC||2pt/A||3 applications|
|Delegate||3-6 oz/A||19.5 oz|
|Mustang||4.3 oz/A||25.8 oz|
|Mustang Max||4.0 oz/A||24.0 oz|
|Entrust||1.25-2 oz/A||9.0 oz|
|Entrust SC||4-6 oz/A||29 oz.|
|Azera*||1-2 pt/A||10 applications|
|Pyganic 1.4EC*||64 oz/A||none|
Insecticide recommendations from Oregon State University, Virginia Tech and NC State University.