Do not spray for weevil or scale on most varieties at this time. You might be able to spray Howes if they are not yet in bloom.
Cranberry IPM Message
We have had reports of various spanworms being picked up in nets over the past week. We have been catching a few Spag moths here and there.
We are hosting a bogside workshop on Wednesday June 20 from 8-10 AM. We will be discussing pest management issues of the day as well as how to collect proper vine samples for diagnosis. We...
Pheromone traps should be out now. Place them on the upwind side of the bog so that the scent flows onto your bogs with the prevailing winds. Spag larvae have been picked up. If you are finding them in your sweep nets, the threshold is 1-2 on average. You should treat as soon as you can. The weather has not been good for spraying, so when you have a good window, you should take it.
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.