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IPM Message for Cranberry Growers: Jun 13, 2012

Jun 13, 2012

First fungicides are going out now (or have been applied for advanced bogs).

We are looking for bogs with Poverty Grass and Phragmites. If you have either of these weeds, please contact Hilary at ext 21, hsandler@umass.edu or Chelsea at ext 27 chedderig@bridgew.edu. If you are using Poast, be careful of your blooms as the crop oil that is mixed with the herbicide can injure sensitive blossoms. 

The season is ahead in many locations and very slow in others. We have seen a wide range of growth and flowering stages out on the bogs. Some are barely at 5% open blossom and other sites have pinheads and bigger. To properly time cranberry fruitworm (CFW) sprays, the biggest point is to know what stage YOUR bog is at with respect to %OUT-OF-BLOOM. This can sometimes be confused with %IN-BLOOM, which is used to time FUNGICIDE and/or FERTILIZER applications. CFW sprays should go out at 50% OUT-of-bloom (0-7 days) for all varieties except Howes (apply 7-9 days after 50% OOB). Refer to Page 15 in the 2012 Chart Book for directions on calculating %OOB. You should get at least one (but 2 is better) sampling BEFORE 50% and then one sampling after. 

A reminder that Altacor is not intended for use as a clean-up spray. It is NOT effective against large caterpillars or adults. It is meant to be used as an ovacide, which kills eggs. It is effective against the eggs of Spag and cranberry fruitworm. So, it is really important to know what stage of the life cycle is out on your bog before making an insecticide application. These materials are quite expensive and should be used wisely for both environmental and economic reasons. If you choose to use Altacor, your system should be 6 minutes or less and this is the only compound that has NO bee toxicity. 

It is probably too late to be spraying for cranberry weevil (eggs are in the pods already) and for spag larvae. Spag adults are flying and have been for about 1 week. If treating with Intrepid or Confirm, apply 3 weeks after moth flight begins and again 10-14 days later. Conventional insecticides are applied 10-14 days after PEAK flight. 

Many sites have green spanworm moths flying. This is notable in that the numbers are higher than usually seen. Even sites that have been well managed have some moths flying. Control efforts target the larvae, not the adult moths. Likely the eggs laid this year will not hatch until next spring.

green spanworm moths

Photo courtesy T. Dittl.


Grub damage is high in some locations. The Ent lab has gotten many reports of problems. This may be related to the warm winter. Oriental Beetle is out there and infestations continue to spread. The adults for OB, cranberry root grub and white grub are out there now. Like Altacor, Admire (imidacloprid) also targets the EGGS, not the adults. Applications (soil drenches) are usually made late July but with the advanced season, applications may need to go out a few weeks earlier. Be careful with bees with this product.