as soon as possible after harvest is complete.
, once you have confirmed SWD presence at your farm with traps or fruit infestation or field history predicts early infestation, once fruit coloring begins you should follow the 3 point program of
1) frequent and thorough harvest
2) prompt refrigeration of harvested fruit
3) spray program (organic or conventional) using recommended materials at intervals of no more than 7 day, rotating IRAC classes to avoid developing a pesticide resistant SWD population.
In addition, keep in mind that if a significant rainfall occurs after a spray application, the material may need to be reapplied. See article from Michigan State University on
Rainfast Characteristics of Spray Materials.
Once harvest begins, it is recommended that you conduct a
salt flotation test on your fruit on a regular basis to determine if SWD egg laying has occurred. An excellent description of how this test is performed written up by Ohio State University Extension Specialist Celeste Welty can be found at this location:
http://entomology.osu.edu/welty/pdf/ProtocolSWD_larvae24April.pdf.
It may also be helpful to install some support trellising in raspberries and blueberries to hold heavily fruit laden canes or branches up and off the ground. This creates air space between the humid shady ground (which SWD like) and the susceptible fruit and can lessen infestation levels.
Finally, exclusion netting has been shown to provide some protection from SWD infestation and can be a viable option for certain situations, especially for organic growers whose spray material options are very limited. See
this article from UVM that describes their findings using exclusion netting. Another excellent source of information on the use of exclusion netting can be found in a Northeast SARE report from New York Berry Grower Dale Ila Riggs at:
http://mysare.sare.org/sare_project/fne14-813/?page=final&view=print.
What does this mean