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IPM Message for Cranberry Growers: Apr 8, 2010

April 8, 2010

We have a new fact sheet for winter moth available on the web site: Winter Moth Factsheet 2010.  It has some color photographs to help aid in identification and management.  With the warm weather we have been having, larvae could be emerging a bit earlier than the usual mid-late April.  Eggs begin hatching in mid-April.  Researchers at UMass are predicting high numbers of WM based on moth flight.  The newly emerged larvae look like black-headed fireworm larvae; it is very hard to tell them apart at this stage.  There is no defined threshold but as young larvae they can be quite voracious and do a lot of damage.  The Ent lab’s general gut feel at this point is that if you find an average of 10 or more, you should consider treating.  Once winter moth caterpillars become free-feeders, they are easier to control but have likely done most of their damage by that point.  Be prepared to sweep early than usual (early May) and sweep more often, especially if you have had injury in the past.  Orthene, Avaunt, Intrepid, and Delegate are good choices for control; Sevin and Diazinon are NOT as spanworms are often resistant to these compounds.

EPA granted our emergency exemption request for the use of QuinStar for dodder control in mid-March.  Growers can use up to 12.5 fl. oz/A per application of the 4L, not to exceed 16 fl. oz/A per season with a maximum of two applications.  In a similar fashion, growers can apply up to 8 oz/A per application of the Dry Flowable formulation, not to exceed 10.67 oz/A per season with a maximum of two applications.  Irrespective of which formulation you use, up to 2 applications can be made, not to exceed a total of 0.50 lb active ingredient/acre per season. 

Due to residue concerns for product bound to foreign markets, OS is prohibiting the use of QuinStar in 2010.  All growers should verify that their handlers will accept fruit treated with quinclorac PRIOR to treatment.

We have VERY limited data for its efficacy in MA.  Be very selective about which bogs you treat; do not treat large areas of bog.  If you can apply QuinStar (that is, your handler will take treated fruit), applications made earlier in the season (pre to early postemergence of dodder seedlings) seem to be most effective.  Scout for early emerging seedlings on your bogs and time your application based on the appearance of seedlings.  Applications made once dodder has attached to its host are much less effective, and if fruit are present, are more likely to present a residue risk.  A 30-day interval must elapse between applications and QuinStar has a 60-day PHI.

If you have any questions about using QuinStar, please call me at ext. 21 and/or contact your handler.

I have two numbered compounds that may be effective against woody perennials like poison ivy and dewberries.  If you have an area that you would be willing to let me try these compounds, please call me. We would set out the plots this summer and treat them next spring.  Any fruit would need to be removed (which we would do) prior to your harvest since there are no food tolerances for these products.

The CCCGA’s frost service will be activated this Friday April 9 for all eligible members.