06/01/2026
I highly recommend soaking in water bowl with some vinager and rise and repeat
If you have ever raised blackberries and picked beautiful berries only to be soft and mushy, then open them up to see tiny larvae inside, more than likely it's Spotted-Wing Drosophila.
Tips for Avoiding Breakthrough Spotted-Wing Drosophila Infestations in Blackberry
Blackberries are already being picked across Arkansas and growers should be spraying weekly for spotted-wing drosophila (SWD). SWD is a major threat each year and the recent rain and cloudy
weather is likely gearing us up for a higher risk of infestation. In both 2024 and 2025, an early warm-up followed by periods of cooler and wet weather prior to and at the beginning of harvest season were a recipe for high infestation pressure for many growers. Depending on where you are in the state, you
may have gotten rain almost every other day for the last couple of weeks, which is exactly what we see in high infestation years. Any growers late starting their spray schedule for SWD will be more heavily impacted as the year goes on, as these first few sprays are paramount in keeping the population down in fields. See below for recommendations on management throughout the rest of the blackberry picking season.
Late Spray Schedules Increase Risk of Infestation
The main issue we seem to deal with each year is when to start the SWD spray schedule. We often see many farms apply the first applications after the first harvest, which yields many larvae in
berries. Research consistently suggests these first few sprays are the most important, and growers need to use the best products first (bifenthrin, fenpropathrin, zeta-cypermethrin, and malathion). No insecticide 100% suppresses spotted-wing drosophila infestations. This means we want to keep those numbers as low as possible, so 90% suppression only leaves a few successful larvae that we can hope to kill with cold storage, etc.
Integrated Management is Paramount for Successful Control
Early sprays with highly effective products will keep SWD numbers down, but without integration of cultural tactics, acceptable levels of control will generally not be realized season long. This is especially evident in “bad” SWD years where populations quickly get out of control. Below I will go through some ways to manage the environment on blackberry farms and make it less amenable for SWD.
1. Prune plants to maximize airflow and light pe*******on. Research shows that SWD prefer shaded, humid and cooler environments during the day.
2. Harvest fruit as soon as they are ripe. SWD are attracted to ripe or ripening fruit and will lay eggs on blushing fruit when populations are high.
3. Increase harvest frequency when possible. This lowers the exposure time of ripe blackberries to SWD adults which will mean less risk of egg-lay.
4. Do not leave culls on the cane or drop them within the field. Getting culled fruit out of plantings and disposed of will drastically reduce the number of flies. This is one of the key areas
where many Arkansas growers are hurting their management efforts.
5. Move berries to cold storage as quickly as possible. Getting berries close to 32°F will slow/stop the development of eggs and larvae, and even kill many. There may be trade-offs with berry
quality when you move from hot berries picked in the late afternoon to a cold facility. If problems occur, consider a step-wise manner of cooling down berries but push the envelope as
much as possible.
Tips to optimize spray programs:
1. Make sure your sprayer is calibrated. If you are applying less insecticide than you think, you should expect a large problem with SWD. Also be sure to frequently check that all nozzles on
sprayers are working correctly and within 5% or so flow rate of what is expected.
2. Don’t skimp on spray volume. A minimum of 50 gallons per acre of spray volume is necessary to fully cover plants and adequately suppress SWD.
3. Spray an effective insecticide at least every 7 days. This schedule should begin whenever fruit begins to blush (Picture 2) or when your SWD traps indicate infestations are beginning in
plantings.
4. Make sure your first insecticide sprays are highly effective chemicals
(https://fieldreport.caes.uga.edu/wp-content/uploads/2025/08/AP-121-5_1.pdf). Research shows that keeping populations down early is the key to full-season success.
5. Rotate effective modes of action (IRAC codes) with each spray.
6. Check berries often for larvae. You can use a saltwater rinse to easily quantify SWD numbers in berries. Increase spray intervals if you are finding large amounts of larvae in samples.
https://www.uaex.uada.edu/publications/pdf/FSA7088.pdf
https://www.uaex.uada.edu/publications/pdf/fsa-7079.pdf
Information provided by: Aaron Cato – Extension Specialist Horticulture IPM
