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IPM Message for Cranberry Growers: May 30, 2017

May 30, 2017

All LW floods should be off your bogs by now (or if on the Cape, by the end of the month).  Frost tolerance is 29.5 F once the flood is removed, no matter the appearance of the buds.  Sweep for early season insects and CB weevil.  Generally, no fertilizer is needed on LW bogs until bloom. Casoron for dodder control should be applied soon after the withdrawal but be sure the bog is dry and the soil has drained. Most varieties are in very late roughneck to jewel.

Cranberry weevil is still being found on many bogs at or over threshold and should be managed. Sparganothis fruitworm is big enough to see now (though they are still very small) and management for the 1st generation should go on now (Intrepid, Confirm, Delegate).

Grass herbicides (Poast, Select, Intensity) can be applied at any time grasses are up and growing.  All of these materials work best when applied BEFORE the grass flowers.  You will still get some control after flowering but it won’t be as good as applications made before flowering. Intensity is the ONLY grass herbicide that can be chemigated.  Be sure to get a copy of the SLN (or 24c) label from our web site or local ag suppliers for complete direction and to make a legal application.

If you are using pheromone traps to monitor for Spag, girdler and/or black-headed fireworm, your traps should be out.  Use 1 trap/10 acres and place them on the windward side of the bog.  Check your traps weekly, recording the number of moths captures.  Be sure you are counting the right moths as sometimes nontarget species can be caught.  Depending on your control choice, you will use the trap counts in different ways.  Sprays of Altacor, Intrepid or Confirm for BHF are timed 2 weeks after ONSET (usually around June 20) and again 10 days later. If treating for Spag with Altacor, Intrepid or Confirm, treat 3 weeks after moth flight begins (usually around late June) and another 10-14 days later. If using conventional insecticides (Delegate), treat for Spag 10-14 days after PEAK flight (mid-late July). For BHF, use of conventional insecticides (Delegate or Diazinon) should be used only after bloom is over. Control of girdler is targeted with nematode applications made 2 weeks after the END of flight.