Spotted Wing Drosophila Update, August 24, 2012
Posted: August 27, 2012
What are we finding out this year?
1) Apple cider vinegar is not a terribly effective bait. Work at Michigan State is clearly showing that a sugar/yeast mixture (1 Tbsp. active dry yeast: 4 Tbsp. sugar: 12 oz water) is much more effective than apple cider vinegar. However, some growers who have tried the yeast/sugar mixture have found that it loses effectiveness quickly, and others have mentioned that its attractiveness to other insects has resulted in more bugs to sort through. The SWD will need to be strained out of the solution in order to see them, because the solution is not clear.
2) You don’t need to have a crop in order to have SWD. I was surprised to find that we are still trapping SWD out of a cherry orchard that had no crop this year. This means that there has been no fruit on these trees for over a year, but we are still finding SWD in this orchard. I don’t know where the flies are coming from or what they are feeding on, but they are there.
3) We hadn’t found SWD on black raspberries in the past, but we did this year.
4) Fruit on the ground is a significant source of SWD. Use strict sanitation measures and avoid letting fruit just drop on the ground.
5) This year we had more fruit loss in blueberries than we did last year, perhaps because SWD was present so much earlier.
Once again, if you need additional information on SWD, please see the following fact sheets:
Part 1: Overview and Identification
Part 2: Natural History
Part 3: Monitoring
Part 4: Management
These fact sheets are also available in printed form in many county extension offices, and from the Publications Distribution Center on campus. To order single printed copies of free publications (which these are), Pennsylvania residents may call toll-free 877-345-0691, locally 814-865-6713 or e-mail AgPubsDist@psu.edu.
- Senior Extension Associate