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Cranberry IPM Message

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.

As of the bud check on May 16 (at Rosebrook Bog and at State Bog), all varieties had many buds at Bud Elongation stage and some buds at early Roughneck Stage; all varieties are at 29.5 F. Based on research in Wisconsin, by May, one can expect all buds to have similar tolerance to those with the most advanced appearance.

Cranberry weevil numbers are above threshold (more than an average of 4.5 weevil/sweep set) in several areas.

We have heard of several reports of single gypsy moth larvae; most were off-bog but one was on-bog.  We think it will be a low GM and winter moth year, but if you have had issues with these insects in the past, you should start sweeping and monitor your populations. We also had a report of 1 cranberry weevil on-bog.

Upright dieback symptoms have been reported in many beds, particularly in areas where traffic is high (e.g., loading areas) or where the vines are stressed for any additional reason. There is very little to be done for URD at this time of year.  If the disease has been diagnosed, you should plan to treat with Champ or a chlorothalonil product between April 25 through May 15 next year.

If you have flea beetles out there with numbers “too high” to count, you should spray Diazinon as soon as possible.  Cranberry weevils (second generation) are out and abundant in some cases.  The threshold for spraying is higher for the summer generation; an average of 9 is used to trigger a spray.

Weevil counts are abundant on many sites.  We had counts of 18-30 per sweep on State Bog. Many bee hives are being picked up this week.  So if your bees are gone, you can spray Belay. It is highly toxic to bees. It is inexpensive and goes out at 4 oz/A. Cranberry is getting pulled from the Belay label, so you should use up existing stock when possible.

Most growers are in the midst of fruitworm and fungicide spraying. The week is looking to be very unsettled, so grab whatever spray window you can get.

Altacor is the best early cranberry fruitworm management option; it should have good residual and rainfastness.  Intrepid and Delegate can also be used. Current recommendations are to spray at 50% out-of-bloom for all varieties except Howes.

Green spanworm moths are out flying.  Do not target this stage of the life cycle for control.  Cranberry fruitworm moths are also out, scouting for just the right berry.  Now is the time to be planning your CFW management approach as 50% out-of-bloom won’t be that far away.