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IPM Message for Cranberry Growers: June 21, 2021

June 21, 2021

First fungicides should be going on this week on most varieties.  Some growers sprayed Mullicas and Crimsons last week.  Bees on “in” just about everywhere.  Don’t forget to check your pheromone traps and record your numbers.

We would be grateful to receive feedback from growers who have used Zeus for moss control (or other weeds), especially if this is your second year in a row.  Please email me or Katie ( and

The next period for fertilizer is usually early fruit set but this can vary depending on what you’ve done so far, variety, and other items.  If you have questions about your fertilizer program, please reach out to Peter at or call the station at x29. 

Applications of concentrated Callisto solutions for poison ivy control can go out anytime now.  It is most effective to treat twice in each year and to treat multiple years in a row depending on the response.  The Special Local Needs (24c; SLN) that permits the use the concentrated solution is only available for Callisto; the other generic mesotrione products do NOT have this special labeling and cannot be used in this fashion.

Grass herbicides can also be applied anytime grasses are actively growing, in accordance to timing restrictions for each product type.  Intensity products have SLNs that expand the application window; this exemption is NOT available with other clethodim products, like Select.  Select cannot be applied between hook and fruit set, but Intensity products can.  Intensity One is the only grass herbicide that can be chemigated. The only window of concern with clethodim products is roughneck and we are well past that.  This is the growth stage that is associated with petal fusing.  Poast (sethoxydim) cannot be chemigated.

Growers have asked about making herbicide applications during bloom.  In general, if you don’t have to spray during bloom, that is always best.  However, herbicide efficacy is often based on growth stage of the weed, so if you need to spray during bloom, you can usually do so.  We have not experienced issues with using the grass herbicides or Callisto during bloom.  The biggest issue is usually NOT the herbicide but the ADJUVANT you are using.  Any questions, give me a call or email.