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IPM Message for Cranberry Growers: May 15, 2020

May 15, 2020

Aside from today (which looks to be wet and warm), the 5-day forecast is still looking cool (in the 50s for highs). Certainly, inland areas may get a good scouting day here and there, and you should jump right out and see what’s going on if we do.  You should be gathering up your fertilizer to be ready for applications when the vines start to move.  If you are doing a total slow or controlled release program, 50-100% goes out at pre-roughneck, which is usually mid-May. 

Based on bud development, there may still be time to make a fungicide application for upright dieback control.  The best time is bud swell through bud elongation.  Regarding Mancozeb, Ocean Spray has not yet decided if it will be allowed.  Lassonde restricts QuadrisTop and Mancozebs.  Check with your handler to verify restrictions before using pesticides!

We have heard that growers aren’t seeing efficacy from Zeus yet.  There have been a lot of frost nights and rain this spring, and we don’t know how this will impact efficacy. Do not to expect fast results on haircap moss; it may take 1 or 2 months to see.  Please let Katie and me know what you are seeing.

Now is a good time to see scale damage and if you think you have them, get a dozen uprights (from base) from area of damage and drop off at the station (in cooler at front door) with name and site for confirmation. Call Marty to let her know you will be dropping samples. Erika from Ocean Spray netted 12 weevils in Taunton and possibly a few winter moth larvae. New scale samples are coming in, with live scale. It’s not too soon to be thinking about gathering up your supplies for pheromone traps.  These go out by June 1.  We can trap for Sparganothis, black-headed fireworm, and cranberry girdler.

Some early season grasses are up and you should treat. Our grass herbicides permit multiple applications and you can take advantage of that depending on what suite of grasses you have.  Avoid applying during roughneck if at all possible.  Remember, Intensity and Intensity One are the only clethodim products that can be chemigated.

For those of you who held late water (LW) and withdrawing the flood this week, keep in mind the following:

Irrigation: For at least 2 weeks after the LW flood is withdrawn, there should be no need to irrigate (unless protecting for frost). We recommend that you schedule irrigation based on soil moisture status determined by sensors or tensiometers.

Frost protection: After LW flood, buds are sensitive to frost injury. If you held the flood for > 2 weeks LW flood: Protect the bogs for 30˚F regardless of what the buds look like.

Fertilizer use: Nitrogen (N) dose should be reduced to avoid overgrowth. The best tactic is to add no fertilizer for at least 2 weeks after the flood withdrawal and then time your applications by the plant’s development. No fertilizer should be needed until bloom.

             < 3 weeks flood: standard fertilizer regime

              > 3 weeks flood: Reduce N dose (30-40%) by eliminating the spring application and/or reducing the fruit set dose.

We will be holding a virtual (zoom) Grower Lunchtime Bogside on Wednesday May 20, 2020 12:00-1:00 PM. One contact hour will be offered. Please contact Robyn Hardy at or 508-295-2212 x10 for the meeting information.