Crop Profile for Strawberries in California - Regional IPM Centers

primarily a contamination problem.
Description of Pest. Vinegar flies, also known as fruit or pomace flies, are small, yellowish flies. This
pest has become more important in recent years with an increasing need for alternative control methods.
Monitoring. No monitoring or treatment guidelines exist for vinegar flies in strawberries, although
yellow sticky cards are sometimes used to monitor adult fly populations. Adults and their offspring may
be monitored with fermented fruit traps consisting of a container filled with overripe fruit covered with
an inverted funnel.
Cultural:
Controls
● Removal of Ripe Fruit. Growers limit breeding sites for fruit flies by making certain that ripe
fruit are completely removed from the plants. When possible, harvest intervals are shortened as
temperatures increase.
● Sanitization. Good sanitation is practiced in and around the field with growers cleaning up
external sources of flies such as cull piles of strawberries or other rotting fruit in nearby acreage,
such as citrus groves, where old fruit may be on the ground. This practice is rarely performed due
to labor costs and worker shortages.
Biological:
There are no known biological controls that specifically target vinegar flies.
Chemical:
Vinegar fly eggs and larvae in the berries cannot be killed using insecticides. Treatments are applied to
kill adult flies.
● Naled. 1 day PHI. Naled (DIBROM) is the most common treatment for vinegar flies. It is an
organophosphate that is applied at rates of about 1 lb ai per acre. It was applied to about 18% of
the state's acreage. When used naled is typically applied once a year. Naled provides good late
season control but is not used when temperatures exceed 85°F due to phytotoxicity. Use is
typically limited to regions where the end of the season is cool. The restricted-entry interval for
naled is 24 hours.
● Malathion. 3 day PHI. Malathion provides effective control of vinegar flies. Malathion is applied
at an average rate of 2 lb ai/acre to 55% of strawberry acreage. The restricted-entry interval for
malathion is 12 hours.
● Methomyl. 3 day PHI for fresh strawberries and 10 day PHI for processing strawberries.