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IPM Message for Cranberry Growers: Apr 10, 2020

April 10, 2020

Chart Book updates are going in the mail today April 10 by both email and snail mail.  If you need a new Chart Book, contact Krystal at to arrange a pickup.

From Peter J: Frost tolerance information (as of Thursday April 9):

  1. BL is now at 22 F tolerance
  2. EB, ST, Howes have not broken dormancy
  3. Hybrids (Rutgers—CQ, DeM, MQ) are now at 22 and need to be protected.

Archival pictures of these frost tolerances can be found at:

Or you can refer to:

Spring Frost Tolerances for Cranberry Buds Photo Fact Sheet (2019)

We will be holding 2 virtual (zoom) Grower Lunchtime Bogside meetings to discuss matters of the day, scheduled for: Thursday Apr 16, 2020 12:00-1:00 PM. Topics will include newly registered herbicide Zeus, scouting for scale as vine is coming out of dormancy, timing and chemical options for upright dieback, and frost and Wednesday May 6, 2020 12:00-1:00 PM. We will discuss more herbicide timing, early season insect management, winter moth, gypsy moth and blackheaded fireworm, and continued timing and chemical options for upright dieback as well as fairy ring.  Please contact Robyn Hardy at or 508-295-2212 x10 for the meeting information.

We have a Special Local Needs label for the herbicide, Zeus, which can be used to control of moss. Applications should go out BEFORE the buds reach cabbagehead stage to minimize injury to the vines.  It is Zone II restricted, so if you want to apply in a Zone II, email me your bog’s address (and GPS coordinates, if you have them).  Zeus may control other weeds, such as dodder, and it is legal to use the herbicide to target weeds other than moss.  Please see our March 2020 newsletter for more information.  We would NOT recommend using Zeus on new plantings; the label recommends use on established fruit plantings. We are recommending that you treat only a small bit of your acreage in 2020 as we do NOT have experience using Zeus through the chemigation systems on commercial farms.  We suspect it should be fine, but we want to start small and mitigate any possible issues before people start to use it on a large scale.

We also have a Section 18 Emergency Exemption to use Kerb for dodder control.  The permit is active from April 15 through June 30, 2020.  Copies of the label are available on our web site at:

and from wherever you will buy your product.  You will need to report your use of Kerb to MDAR by November 30, 2020 but to the best of my knowledge, the 2020 forms are not yet available.  Feel free to contact me later to inquire about the availability if you need one.

Late Water floods for inland areas usually start now, Coastal Plymouth is April 15-20 and the Cape is usually April 20 or later.  Bear in mind, these time frames were generated with Early Black and Howes in mind. If you have large-fruited hybrids (and particularly if your farm is inland), you should be out there right now!, so that you get your flood out at the right time.  Conventional Wisdom says that floods should not be held if vines appear stressed coming out of the winter.