Massachusetts IPM Berry Blast
July 8, 2016
Spotted Wing Drosophila - First Find
The Massachusetts SWD monitoring network has recorded it's first find of the 2016 season. One male and one female SWD were found in traps in Hampshire County on 7/8/16. No other captures have been reported in the state yet, but are expected in the next week. New York has been reporting trap captures for the last couple of weeks, also at very low numbers and with few repeat captures at any locations. Ontario has reported captures for several weeks now. And, Rhode Island has reported a single incidence of infested fruit (summer raspberry), but no trap captures.
We expected the SWD 'season' to be somewhat early this year as compared to previous years based on a relatively mild winter and reports from southern states that their SWD populations showed up early. Our first find was in late June last year and not sustained captures until mid-July. This year we don't yet know when we'll have sustained captures but it may be around the same time. The dry weather in New England has helped keep this pest at bay, but now with some recent rains and more expected, it is likely that the population will begin to build up in available hosts.
What does this mean?
• For strawberry growers, mowing and renovating fields promptly following the end of harvest is highly recommended. Some states are recommending an insecticide spray to the field prior to tilling in order to knock down SWD that might be building up in unharvested fruit. This could be especially helpful if strawberries are near other berry plantings (summer raspberry or blueberry).
• For all susceptible fruit, keeping an open and airy canopy to promote air circulation and light penetration is a key element in successful SWD management. Some of this is accomplished during the winter pruning season. But now, you can still improve conditions by making sure to keep weeds down between blueberry, currant and gooseberry bushes and by maintaining a narrow row for raspberries and blackberries. Image to the left is an example of a very weedy blueberry field where SWD have ample shelter and good conditions for fruit infestation. Weed wacking the space between bushes can help improve this situation significantly.
Note Hummingbird feeder in photo: Hummingbirds can be an asset, especially in organic systems. Encouraging them by placing feeders around the field can result in some suppression of SWD populations according to reports from southern states.
• Possibly the most important action you can take to keep the impact of SWD on your fruit low is to harvest frequently and thoroughly. Avoid leaving ripe fruit in the field and don't allow cull fruit to be dropped to the ground. Give harvest staff or PYO customers a second container in which to put cull fruit and provide an incentive for doing so (additional pay, discount on final cost, etc.).
• Monitor harvested fruit by using the salt flotation test. This will alert you to cases where management practices may not have kept SWD out of your fruit. It is better for growers to know this before selling fruit than for them to be alerted to it by customers. See here for a good protocol for the salt flotation test.
• For summer raspberry and blueberry growers, if you had early infestations last year, now is a good time to begin your spray program. Remember to rotate chemical classes (IRAC code) of materials used so as to avoid promoting a population that is resistant to any particular material. See here for information on recommended labeled spray materials.
• Specially designed insect exclusion netting
is another viable approach for keeping SWD away from susceptible fruit. Now is a bit late to begin installing this system, but for interested growers who want to try to use this tactic next year, a good write up of the system can be found at: http://mysare.sare.org/sare_project/fne14-813/?page=final&view=print
(Photo Credits: Cornell University, Michigan State University, UMass)
Archived IPM Berry Blasts are available at the UMass Extension Fruitadvisor website.
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