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IPM Message for Cranberry Growers: Apr 24, 2020

April 24, 2020

The Preliminary Keeping Quality Forecast is FAIR; we got 3 out of 10 points.  Based on the preliminary forecast, fruit rot fungicide applications and the rate of fungicides applied for fruit rot control should not be reduced. As for the holding of late water this year, there are no definitive indicators pro or con.   As of Wednesday April 22, BL were at 25 F frost tolerance, EB and ST were at 22 F and Howes were at 20 F. It’s been an active frost season. Just since April 15 (9 nights), we have had forecasts for very dangerous frost 5 times and possible frosts 3 times. Some of the frost nights have started very early (8-9 pm).  It is certainly in these conditions that cycling is really helpful to keep your bog from getting drenched.

Most handlers are permitting spring applications of Bravo or other chlorothalonil products for upright dieback control; check with your handler before using.  Applications typically go out between April 25-May 15.  Best results occur when the fungicide is applied when the bud is expanding and starting to elongate.  Don’t go too early.  Applications dates will vary greatly based on location and variety.

If you think you have Phytophthora, make sure you get a diagnosis first before applying any fungicides.  Please contact Leela at 334.728.1025 to arrange a drop-off of your sample.  Also, once diagnosed as positive and before applying any fungicides, improve drainage first.  Otherwise you will be pouring money down the drain.  If you are in a position to apply fungicides, the first application goes out between April 24 and May 15.  See P13 for the suite of fungicides available for use against Phytophthora.

First applications for Fairy Ring go out in early May at budbreak.  You need to irrigate for both before and after applications.  A combination of Indar and Abound are the recommended fungicides for this treatment and they are applied as a soil drench.  This is pretty labor intensive (but not as bad as the Ferbam drench). You should treat the affected area plus a 10 ft outer margin. To stay within the label rate per acre using this drench, you can treat about 4300 sq ft. Repeat applications (with Ferbam) can be made if needed 2 weeks later.

We will be holding a virtual (zoom) Grower Lunchtime Bogside Workshop on Wednesday May 6, 2020 12:00-1:00 PM. We will discuss the issues of the day.  One contact hour will be offered. Please contact Robyn Hardy at or 508-295-2212 x10 for the meeting information. Ocean Spray is also offering a workshop on Monday April 27, 4-5 pm; Leela and I will be presenting. Contact Erika Saalau-Rojas for more information.
Within another week or so, the window will be closed to use Zeus, our new herbicide. It should go out between spring dormant and cabbagehead. It is Zone II restricted, so contact me if you want to use it in a Zone II ( Please see our March 2020 newsletter for more information.  We would NOT recommend using Zeus on new plantings.


Here are some pictures taken of buds on 4/23/20: Early Black, Stevens, Howes, Ben Lear, DeMoranville (top row), Mullica Queen, Crimson Queen (bottom row)

Early Black 4.23.20 Stevens Howes Ben Lears DeMoranvilleMullica QueenCrimson Queen