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IPM Message for Cranberry Growers: May 25, 2018

May 24, 2018

Weevil continued to be swept in high numbers on some bogs over the past week.  Avaunt is effective (weevils die in the lab) but environmental conditions can play a role in efficacy in the field. Spraying just before or during cloudy, rainy, or moist condition may lead to decreased efficacy. The pesticide works best when applied prior to sunny warm dry conditions. Cool temps and little feeding prevent the weevils from ingesting an effective dose of indoxacarb. If you've had rainfall, after 2 weeks there is likely to be little product left out there so a retreatment would definitely be necessary especially if weather improves and weevil activity increases. We did hear a couple of reports of gypsy moth and winter moth larvae collected in sweeps but not in numbers high enough to trigger a spray.

If you are using pheromone traps for Spag, Cranberry girdler and/or black-headed fireworm, they should be set out by June 1.  Place them on the bog such that the prevailing winds will blow the pheromone across the majority of the bog.  Use 1 trap for every 10 acres.  Use fresh lures every 3 weeks for best results and check traps weekly and record the numbers.

If you are using QuinStar as an early postemergence application for dodder control, your window is now in most locations.  You should be scouting for dodder seedlings to determine the best timing.  QuinStar is restricted by most handlers so you should check with your handler PRIOR to using this herbicide.

I have gotten a few calls about Japanese knotweed.  This is a serious invasive weed.  You do not want this getting on your bog!  Control is very difficult and long-term.  The best controls that we can use are mowing and treatment with Roundup.  Mow now to deplete stored carbohydrates; treat later in the season to move the herbicide down into the roots of the plant.  Please call Hilary 508-295-2212x21 if you have any questions.