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IPM Message for Cranberry Growers: July 31, 2020

July 31, 2020

It’s a good time to treat for Poverty Grass and other warm-season grasses. Our grass herbicides are much more effective when applied before the grass flowers.  Remember to add the proper adjuvant with the herbicide.

We have not seen a lot of red berries due to cranberry fruitworm but we have seen quite a few fruit with symptoms of Tobacco Streak Virus. Please see the IPM message from July 24 for photos of the symptoms.  If you see these, please let Leela know (x18) or email

We suggest several approaches to growers depending on their situations on how to deal with heat wave:

  1. Consider doing a predawn irrigation in anticipation of a heat wave
  2. Raise the water level in the ditches
  3. Intermittent sprinkling irrigation at midday or when the trigger of >88F in air temp
  4. Do nothing and hope that the transpirational cooling will do its job

We have also seen multiple spots that folks thought were scale damage but we think they are areas of Phytophthora damage.  We are preparing an article on Phytophthora for our August newsletter due out soon.  Although we typically think of Phytophthora only happening and/or showing up when it’s wet, we think the impact of the disease (destroying the root system) can also show up when it’s really hot. The vines have fewer roots and cannot gather or uptake water in stressed conditions and areas of vines start to dieback.  So again, let us know if you are having issues and we can come check it out.