Bloom is here and as you are getting ready for fruit rot fungicide applications, here are important things to keep in mind.
Cranberry IPM Message
Spag (sparganothis fruitworm) is starting to show up. Larvae can be found in loosestrife tips (see photos below, courtesy Marty Sylvia) and cupped cranberry tips. Pheromone traps reportedly already have caught some moths, so once again, it’s a difficult, spread-out population. Intrepid, Invertid, or Delegate now or later are your options.
Sprays have been going out to manage green spanworm and cranberry weevil. Avaunt has been very effective in most cases, but reports of lower efficacy have been heard.
Buds are pushing out of elongation and even into roughneck at some locations.
As of May 12, we had 24 possible frost nights; 8 were called as dangerous and 7 as possible. 9 nights had no frost predicted. The recent string of frost nights may contribute to waterlogged areas on the bog, so improving (managing) drainage is very important. Proper soil drainage results in optimal aeration of roots, healthy vines and improved fertilizer use efficacy.
There have been reports from early scouting of very small larvae; they are likely green spanworm or winter moth. It is very hard to tell them apart when they are so small. We have also had reports of weevil, but mostly on edges near the woods. We would not recommend spraying right now anyway for high weevil numbers.
Upright Dieback (UDB) continues to rule the day. Orangey-brown dead uprights scattered throughout the greening up vine is an indication of this fungal disease at work. Pictures below show this damage on Stevens and Early Black. All the samples we received with typical UDB symptoms tested positive for UDB pathogen (Phomopsis vaccinii) in lab plating.
Frost update (from Tuesday April 20): EB and H at 20F (white bud stage); BL, ST, and super hybrids at 22 F 9white bud). We had accumulated 99 GDD as of Tuesday April 20.
Frost Update. As of Thursday April 15, we have accumulated 86 GDD (the threshold for frost to start according to the Dee model, using 44F as base T, is 100 GDD). Also note we reached the long day mark on April 7th. For the most recent reports and photos, go to https://ag.umass.edu/cranberry/frost-tolerance-reports.
We have been hearing about many bogs with vines in distress coming out of the winter. Some bogs have leaf drop, some have dead vines and dead spots and some are showing dieback of uprights. More than 20 samples have already come into the Diagnostic Lab. We do not know yet if it is abiotic or...