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IPM Message for Cranberry Growers: June 23, 2023

June 23, 2023

If you are using pheromone traps for timing management of girdler, black-headed fireworm and/or Sparganothis, you should be monitoring and counting moths at least weekly; more visits may be needed if counts are high. Baits should be changed every 3 weeks. Be sure you are counting the correct moths.  Especially in the girdler trap, other/impostor moths can be caught but should not be counted.

For BHF, when treating summer generation with Altacor, Intrepid or Confirm, apply insecticide 2 weeks after the ONSET of moth flight (usually around June 20) and again 10 days later. Conventional insecticides (Diazinon or Delegate) should only be used after bloom is over. See p30 of Chart Book for more info.

For Spag, if treating with Altacor, Intrepid or Confirm, apply insecticide 3 weeks after the moth flight begins (ca. late June) and again 10-14 days later. Timing for conventional insecticide (Delegate) is 10-14 days after PEAK moth captures. See p31 in Chart Book for more info.

No insecticides are currently recommended for girdler. Please see p36 of the Chart Book for current management options.

Green spanworm moths are flying. It is too late to do anything about this pest at this time.

It’s also time to be thinking about cranberry fruitworm management as fruit are setting. Some of the newer varieties have a lot of fruit out there already! To calculate percent out-of-bloom (% oob), you need to go out every few days as pinheads start to form, usually around the end of June. Randomly collect (or assess in the field) 10 uprights and record the number of pods, flowers, pinheads and fruit. Divide the total number of pinheads and fruit by the total number of pods, flowers, pinheads and fruit and multiply by 100. For all varieties except Howes, apply your first CFW spray 0-7 days after 50% oob. For Howes, apply 7-9 days after 50% oob. Altacor is the best choice for first fruitworm. Two applications are allowed but must be separated by 7 days; 10-14 day spacing is better as it has a long residual.

I have gotten a few calls about adjuvants. There are a lot of products out there and we have not tested nor worked with many of them. Adjuvants can have many ingredients (inert and active) and they can behave and interact differently depending on what they are mixed with and when they are used. I would recommend staying with 1 or 2 products that you have used with confidence (crop safety, efficacy) instead of switching around among products.

If you have specific items you’d like to see addressed in the IPM message, please let me know.