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IPM Message for Cranberry Growers: August 13, 2021

August 13, 2021

Sparganothis fruitworm is starting to show up in berries, only about 1/4". If Altacor applications did not get on or if spots were missed, cranberry fruitworm red berries are clear now. Flea beetle are out now feeding on lush growth. Upright dieback has started to appear on some bogs. Poor keeping quality prediction and an unusually wet summer have everyone worried about rot developing before harvest!

Please wear ALL appropriate PPE when handling, mixing, and applying pesticides.  If you are having any issues with a product or have questions on what is the appropriate PPE, please call Marty x20.

Roundup is most effective, especially on well-rooted perennial plants, when applied as the plant is preparing for dormancy.  Applications made when the plant is sending sugars and reserves to the root transports the most herbicide to those tissues and will give the best long-term control. So it is recommended to wait as long as you can to treat while still observing the 30-day PHI.

Now is the good time to collect tissue for nutrient analysis (through September 15). Samples should contain no more than the top 2 inches of growth (no roots, soil, runners, or fruit). Collect tissue from vegetative and flowering uprights. You typically need about 1 cup of vine tissue. Do not collect samples when the vines are wet and do not send the samples in plastic resealable bags. Always request nitrogen determinations when you submit your samples. Due to short staffing, UMass is currently NOT processing tissue samples.  Please try UMaine or a commercial lab instead.

This will be the last of the weekly messages.  If you have particular issues or topics you would like to see addressed, please call me at x21 or email me at

Good luck with harvesting and stay well!