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IPM Message for Cranberry Growers: June 9, 2023

June 9, 2023

Timing for Diazinon (or Sevin) treatment is here (or coming up) for Vaccinium scale. Check your bogs. There is a lot of variation among beds. All scale samples that were checked this week showed that egg production has started. For super hybrid samples, crawlers were emerging, and we advised sprays for this weekend and next week.

For many (but not all, some were advanced) BL, ST, EB or Howes beds, we saw only eggs under scale covers, so we advised waiting until the end of next week (after 6/15) to better target crawler emergence.

You should ONLY treat if you see active infestations. Some suspect spots (orange vines, usually around dieback areas) that we checked had no active scale. Be aware that some growers are seeing treatable scale buildup even if they treated two years ago.

Keep in mind that crawlers are released in mid-June and again in mid-August. We believe that the June population is more synchronous, and thus, is better managed than the August population. Last year, some beds saw severe vine injury from summer populations that flared up with little warning, likely owing to multiple stresses.

Free Insect ID Clinic – Tuesday June 13, 2023, 7:30-9:30 am in person only: Meet in the Makepeace Room (upstairs new building), then we will move to the Entomology lab. You will gain hands-on experience to better ID pests in your sweep net. We will also cover false blossom disease and other issues of the day. 2 credits offered. Questions? Write Anne at or Marty at

We will be hosting an in-person bogside on Thursday June 22 from 8-10 am.  One contact hour will be offered. Meet in Makepeace Room.

Grass herbicides (Poast, Select, Intensity) can be applied anytime grasses are growing and are best applied BEFORE grasses flower. Multiple applications are allowed and are often needed to manage the wide suite of grasses that may be on the bog.  Remember to add an adjuvant as per the label (NIS or COC). Callisto can be mixed with the grass herbicides with growers reporting efficacy.  Any questions, contact Hilary or Katie. or

The window for treating for upright dieback has passed. If you used chlorothalonil for URD, you are only allowed two more applications (if your handler permits) for fruit rot.

Phytophthora samples are coming into the diagnostic lab. The window for the first (spring) treatment is closed. Summer applications are typically timed 60-90 days after the first. Multiple applications should be made until vine recovery is visible. Before starting any fungicide treatment, first confirm that the problem is Phytophthora. Drainage issues should be corrected before embarking on a fungicide program. Please call or email Leela if you have questions at 508-970-7644 or

As you are getting ready for your first fungicide spray, please note that fungicide applications should have good coverage and take place before fruit rot fungi infect plant tissues. Most fruit rot infections occur during the bloom period and early fruit set, before berries start to size up. Your first application should happen before 50% of flowers are opened. Once the fruit has set and begun to increase in size (mid-late July), fungicides are no longer necessary or effective. If you need have questions related to the choice of fungicides, frequency, how to count bloom and time fungicides please contact Leela Uppala ( or 334-728-1025)


Plan an efficient fruit rot management program:

  • Cultural practices are as important as fungicide applications. Any practice that promotes excessive vine growth such as excessive N fertilizer, holding water high in ditches could favor fruit rot development. Other factors that increase the risk of fruit rot include dense vine growth, poor air circulation, high humidity, slow drying-out of dew, and poor drainage.
  • Always read the label and communicate with handlers for making fungicide decisions.
  • If you are considering broad-spectrum fungicides such as Chlorothalonils (eg. 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 (eg. Proline, QuadrisTop, Indar and Abound) due to resistance concerns. Copper fungicides (eg. Kocide 3000, Badge SC, Champ, Mastercop), if chosen, should be applied starting from late bloom.
  • Do not use a fungicide at less than the registered rate.
  • Bloom and early fruit set are susceptible for infection. Monitor bloom on regular basis for timing your fungicide applications.
  • Aim for uniform coverage. Apply materials with low phytotoxicity during fruit set.
  • Avoid sprays when pollinators are working whenever possible.