Bugs on the Bog
This past week proved to be the time to sweep! Despite fairly high winds, many sites had over threshold weevil counts. Populations of weevil are expected to continue to grow as more weevil move out of the woods and off blueberry and onto cranberry. Your choices for management are Avaunt, Actara and Fanfare. Remember Fanfare has a 120-day PHI if on export fruit. If you plan to harvest starting Sept 25, your last spray option with Fanfare would be May 25!!
Green spanworm populations are out there and ranged in size from tiny to up to ½”, but rarely more than just one or two in a sweep set. Consider treating if you find more than 10 spanworm on average. Avaunt is your best choice, but Intrepid and Delegate are also options.
Scale damage is starting to be more clear – orangy dieback areas may indicate scale at work. Contact Marty if you think you have an infestation.
Additional WPS Handler Trainings, June 2 and June 9, 8-9 AM on zoom
Anyone working on the cranberry bogs (bogs that have been treated within 30 days) who does not have a Massachusetts Pesticide Certification needs to have worker protection training each year. I am offering a few more dates on ZOOM that your workers could attend to cover this requirement. This will be a handler training and will allow workers to help applying general use pesticide and apply Roundup (glyphosate) or spot treat with Callisto, Intensity or Stinger. This training can be done with each person on a smartphone or computer, or in a group setting around a screen – but I need verification of each person attending. Paperwork will be completed that covers EPA WPS requirements. Cost is $5 per person. To attend a training or for more information please contact Marty at 508- 265-6921 or martys@umass.edu.
Nutrition
For making decisions on Nitrogen application rates, take consideration of the cranberry cultivar, previous summer tissue tests and historic bog response. Aim to provide enough Nitrogen to produce a stand of uprights with optimal density and length that will provide an optimal crop of good quality fruit. A thin, stunted stand will not support a large crop since there will not be adequate leaf area, leading to a deficit in photosynthesis and a shortage of carbohydrates for making fruit. If the upright stand is too dense or too long, it obstructs pollinators, causes shading and higher retention of relative humidity which is congenial for fruit rot fungal infections.
Disease Management
As you are purchasing and making plans for upcoming fruit rot applications, in compliance with your handler and fungicide label recommendations, incorporate the fungicide resistance management strategies such as 1) Alternation or mixing of fungicides with different modes of action. Use FRAC (Fungicide Resistance Action Committee) codes on the labels to determine the mode of action. Fungicides from the same FRAC codes have similar modes of action. 2) Follow all ALL-label instructions, including application interval, recommended rates, water holding time and pre-harvest interval.
If you are considering broad-spectrum fungicides such as Chlorothalonils (e.g., Bravo Weather Stik and Bravo Ultrex) and Mancozebs (eg. Manzate Max, Dithane M-45) as part of fungicide regimes, please use them early in “the possible infection period” or “disease development phase” (when the maximum number of flowers are open: Early to mid-bloom). Do not apply more than two applications of Group 3 and Group 11 fungicides (e.g., Proline, QuadrisTop, Indar and Abound) due to resistance concerns.
Copper fungicides (e.g., Kocide 3000, Badge SC, Previsto Champ, Mastercop), if chosen, should be applied starting from late bloom. Based on our 2021 and 2022 studies, Copper products showed efficacy in managing fruit rot when applied as part of fungicide regimes.
Please note that there is a correction to the Chart Book Update from 2022: under Disease Management. Howler, recommended application rate should be 5 lb/A not 5 fl oz/A.
If you suspect Phytophthora Root Rot in your bog or have any disease related questions, please contact Leela Uppala (508-296-5330) or suppala@umass.edu.
