Growers have been reporting seeing “umbrella bloom” on beds this year. This is the condition when the terminal bud of an upright produces flowers, but there is no vegetative tissue formed above the flowers.
On a normally developed flowering upright, there is at least 1-2 inches of new growth above the flowers. That vegetative tissue above the flowers is where most of the carbohydrates are made to support fruit during development. Despite the fact that there are flowers present on umbrella bloom uprights, the consequence of having no tissue above the fruit means less food to support fruit development and reduced yield on those uprights.
Umbrella bloom can be caused by a lack of chilling (not enough cold hours accumulated over the winter) or by frost injury. In the case of what we are observing this year, frost or winter injury is the likely culprit.
From the 2008 Cranberry Production Guide: “Buds injured later in the spring may sustain injury only to the vegetative portion of the bud. Such buds may go on to produce flowers with no vegetation.”
Frost injury can result in injury to the floral initials only (can still develop healthy vegetative tissue but will result in no flowers) or damage to the vegetative part of the bud only (can develop flowers but no vegetative tissue, aka umbrella bloom).
Insects
Most growers who had high counts of Cranberry weevil have treated the populations with general success. If high weevil counts are occurring now, they surely will be laying eggs into the flower pods guaranteeing a second generation in July. Flower pods are being seen on many varieties now and timely management of any weevil counts over 10 should be considered. Fanfare, Avaunt, and Actara are the only options for weevil management (Fanfare can only be used once for export fruit).
Green spanworm, on many bogs, is completing development. If you are sweeping inch long inchworms, it is too late to manage this insect. If you are still finding smaller caterpillars in high numbers (over 10 on average) a spray of Avaunt may be warranted.
A few sites have been confirmed to have black bug nymphs and blunt-nosed leafhopper nymphs. Be aware that these “new” pests can cause problems for your bog. Be aware that these insects are really, really small. Assail or Arvida (acetamiprid) is a good option (with sticker) or Fanfare.
Scale spots have started to appear. Off-color round areas may be percolating scale spots. Inspect the uprights for small round black spots towards the base of the upright. Samples of uprights can be dropped off at the station or you can use the microscopes in the diagnostic lab yourself to look! If you confirm that you have a live scale infestation, you should wait until mid-June to manage this insect. They are protected under their covering until they start releasing their crawler phase.
Commercial bumblebees are expected to arrive next week, mid-week! Migratory honeybees will likely start trickling in the second week of June.
Disease
There is a huge range of bud development stages out there. We have seen everything from beds with some buds still at cabbagehead to beds that are starting to enter bloom!!! Although it is too early for to spray for fruit rot (applications begin between 10-50% bloom), it is not too early to start thinking about your fungicide program and formulating a plan. Use fungicide resistance management strategies by rotating or mixing fungicides with different modes of action. To help slow resistance development, limit applications of Group 3 and Group 11 fungicides (such as Proline, QuadrisTop, Indar, and Abound) to no more than two total applications per season from that group.
The pathology lab is studying the distribution of Phytophthora species in Massachusetts cranberry bogs. If you suspect Phytophthora infection in your bog, please consider submitting a sample for testing
Upcoming workshops at the Cranberry Station
1. Bogside Workshop (no credits) Free - Tuesday, June 3, 2025
8:00-10:00, AM Hybrid (you can attend online or in person in AD Makepeace Room, UMass Cranberry Station)
You can join the meeting by Zoom or in-person. Here is the link:
https://umass-amherst.zoom.us/j/95022345182?pwd=pZoqATjHiW7jZgjJR7m75q8O35pubV.1
Meeting ID: 950 2234 5182
Passcode: 503956
AGENDA
8:00 Phytophthora root rot and Fruit Rot Management – Leela Uppala
8:20 Cranberry Weeds – Katie Ghantous
8:40 Winter injury and Spring Frost – Peter Jeranyama
9:00 Drones for frost/scouting in the spring – Giverson Mupambi
2. Insect and Disease Clinic III (2 credits) Free - Thursday, June 12, 2025
8:00-10:00 AM, In-person, AD Makepeace Room, UMass Cranberry Station
Interested in Internal Fruit Feeders??
Get a review of the history, the lifecycle, and the management of our two biggest summer pests in cranberry, Sparganothis Fruitworm and Cranberry Fruitworm. In addition, there will be a quick review of our other big problem; fruit rot, including a discussion of the limited options available to manage. Hosted by Marty Sylvia, Crysta Taylor (Ocean Spray), and Leela Uppala.