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IPM Message for Cranberry Growers: Jun 19, 2020

June 19, 2020

Sparganothis fruitworm moths and Cranberry fruitworm moths are flying.  There are pictures on the IPM Message on the Cranberry Station web site. Picture #1 below shows a cranberry fruitworm moth resting on a pod waiting patiently for a cranberry to lay its egg on.

Green spanworm moths are really flying!  Picture #2 below shows green spanworm moth and pupae, picture #3 shows what the moth looks like on the bog after it has lost most of its coloration (wing scales).  These moths lay eggs that will overwinter and be the spanworms you see next May!

Weevil sprays are done, it’s too late to spray now.  Scale sprays went out this week, don’t spray not unless you have no bloom and no bees. First fungicides should be going on now.

We would be grateful to receive feedback from growers who have used Zeus for moss control (or other weeds).  Please email me or Katie ( and ).

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 compared to other clethodim products, like Select.  Select cannot be applied between hook and fruit set, but Intensity products can.  Select cannot be chemigated; Intensity products can. The only window of concern with clethodim products is roughneck.  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.

Sparganothis fruitworm and Cranberry fruitworm Green spanworm Green spanworm