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IPM Message for Cranberry Growers: August 4, 2023

August 4, 2023

We have been fielding several calls about mixing pesticides. You should ALWAYS do a jar test before mixing a new combination of pesticides in your tank.  We have tried Delegate and Callisto and do NOT recommend that combination; it forms clumps and would be a big problem in your tank. People have asked about mixing coppers and Callisto. I have not had experience with that combination. Here is the link to doing a jar test. You should check for clumps, formation of layers, discoloration, heat or cold.  Do not combine if you see any of these. You should only combine pesticides that form a nice smooth solution when combined together. Fact sheet on how to do a jar test can be found here:


We have also had a few calls about treating for dodder. The best option is to treat dodder before it flowers and certainly before it sets seeds. You can get some control once flowering/seed set has occurred but it is much less than if you apply treatments before. Concentrated solutions of Callisto (1-1.5 oz + 1.5 oz NIS per gallon water) work, as well as using flame cultivation.

Most bogs are well into fruit sizing now and bloom has passed. There is no value to applying fungicides once the flowers are gone.

Now is the time to look close at your bogs for vaccinium scale (see photo). Dead areas with dead vine at the edges are not signs of scale. Completely dead brown uprights are drought or old damage. Areas with mottled color change are the indicators of a current infestation that could be treated with Diazinon in the next week or two. Not seeing a lot, not like last year, but it's worth looking!

The next IPM message will be posted on August 18th.

Scale damage on cranberry