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IPM Message for Cranberry Growers: Aug 16, 2019

August 16, 2019

Cranberry fruitworm larvae are full-sized now and berry inspection typically ceases by August 15.  Sparganothis fruitworm larvae are reported at about half size.  It is really too late to be spraying for any insects at this point.  The only possibility could be flea beetle and you should have very high numbers prior to considering treatment.  Diazinon remains the best choice here; Delegate and Actara are much less effective. Please call Marty or Anne if you have questions (x 20).

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.

It is too late for additional fungicide applications as well.

Now is the good time to collect tissue for nutrient analysis (through September 15). Please see the previous two IPM messages for specifics on collecting tissues.

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!