Back to top

IPM Message for Cranberry Growers: June 2, 2023

June 2, 2023

We have dissecting microscopes available in our Diagnostic Lab (Rm 121) and in our Entomology lab (Rm 106) that you can use to examine your sweep net contents or upright samples.  Just come on down, the labs are available 8:30-4:30. If one of us is around, we are glad to help or you can do the inspection yourself, whatever works best.

When making plans for upcoming fruit rot applications, in compliance with your handler and fungicide label recommendations, incorporate fungicide resistance management strategies such as alternating or mixing fungicides with different modes of action. Use fungicides from different registered FRAC (Fungicide Resistance Action Committee) codes; fungicides with the same FRAC codes have similar modes of action and should not be used repeatedly.

If you are considering broad-spectrum fungicides such as Chlorothalonils (e.g., Bravo Weather Stik and Bravo Ultrex) and Mancozebs (e.g., 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.

For making decisions on nitrogen application rates, consider cultivar, previous summer tissue tests and historic bog response. Aim to provide enough nitrogen to produce uprights with optimal density and length that will provide 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 uprights are too long or dense, they obstruct pollinators, cause shading and higher (localized) humidity, conditions which favors fruit rot fungal infections.

Weevil numbers continued to be high this week and applications of Avaunt, Actara or Fanfare have targeted them.  As blossom buds appear, the weevil are laying their eggs in them.  Green spanworm is wrapping up its feeding and about ½ have turned into pupa and will start flying next week and the week after.  Scale damage is becoming more apparent as bogs should be fully greened up by now.  It looks unlikely for an early crawler release this year. Stay tuned for difficult timing after June 10th and hold your bees off if you plan a Diazinon management spray.  If you have a population that needs assessment, bring in a bag of scale infested upright to the Entomology Lab or call Marty for update (508-265-6921)

The third (and final) Hands-on Bug ID workshop will be held on Tuesday June 13, 7:30-9:30 am. Meet in the Makepeace room and then we’ll go to the lab. 2 contact hours offered. We will be hosting a Bogside Workshop Thursday June 22 from 8-10 AM in-person at the Station. 1 contact hour will be offered. We will cover issues of the day. To participate, join us here at the station next to State Bog or contact Robyn Hardy at 508-970-7635 or