Back to top

IPM Message for Cranberry Growers: May 18, 2018

May 18, 2018

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. In other words, even buds that have not begun to elongate will exhibit the same tolerance as the elongated ones. Once buds have reached the Cabbage Head Stage and associated tolerance, the tolerance advances a stage every 5-7 days even if there is no visible change in appearance. At Elongation Stage, the bud begins to grow upward. Early in this stage, when the bud is observed from above, the cabbage-like appearance remains. However, a side view shows the outward/upward expansion. As the bud grows outward (upward) to about 0.25 inches, it is at roughneck stage. Roughneck Stage tolerance for all varieties is 29.5°F. From this point forward, tolerance of the new growth remains at 29.5°F. Remember: once Cabbage Head Stage is reached, bud tolerance advances every 5-7 days even if appearance does not change.

Marty has continued to find and hear about very high numbers of cranberry weevil from several locations throughout cranberry country.  The weather has been unstable, so if you see a window to spray and you need to spray, you should spray!!

If you are holding LW floods, floods should already be off inland locations. Coastal Plymouth County floods should be off by the 20th and Cape bogs with late water should remove their floods by late May.  Remember, frost tolerance is automatically 29.5 F once the flood is removed, no matter the appearance of the buds.  LW bogs must be swept for early season insects, even though we do not think it will be a bad year for gypsy and winter moths.  Heather Faubert from URI reported 12 days ago that winter moth hatch was just about over and very few caterpillars had been seen in commercial fruit crops. CB weevil is NOT impacted by late water and you should be on the lookout for those as well.  We recommend NOT adding any fertilizer to a LW bog for at least 2 weeks after the flood comes off. Monitor the vines closely and add amounts based on vine response.  Generally, no fertilizer is needed until bloom. Casoron can be applied for dodder control to a LW bog if needed.  Apply soon after the withdrawal but be sure the bog is dry and the soil has drained.

Non-LW bogs: If you are applying Casoron, Callisto or QuinStar for dodder, in most situations you will be targeting to get your herbicides out in the next available window.  Dodder will “pop” if we get the high temperatures that are predicted and the window for getting good efficacy could close pretty quickly.

For most situations, the window is now closed for spring applications for control of upright dieback, fairy ring, and Phytophthora.  If you are using slow or controlled release fertilizer, 50-100% goes out around mid-May.