Cranberry Weed and Insect Update!

Thursday, June 27, 2013

Hi Folks,

I've been out to a few cranberry bogs in the last while and the potential crop is looking pretty good!  Lets hope the pollinators are busy over the next few weeks - fingers crossed for warm weather and sunshine!

Weed control continues to be an issue for many growers - the new registration of two applications of Callisto does seem to be making a difference on some of the problem weeds like narrow leaf goldenrod, sedge, and dewberry!  Drop me a line and let me know if you've used this product under the new label this year and how it worked for you! 

Cranberry insect number in sweep counts have been quite low this year - perhaps a positive by-product of that cold winter and spring - there's got to be a silver lining right? 

We are getting close to bloom in some areas of the province so I thought it was timely to post my calculating % Out of Bloom instructions for timing your cranberry fruitworm sprays.   And it's also time to remind you that the thinking on when to apply cranberry fruitworm sprays has been revised.  Click here for the full presentation on this change. 

In the past, it was suggested you apply your sprays 3-5 days AFTER 50% out of bloom on Stevens, 5-7 days after 50% out of Bloom on Ben Lear and for Howes or Early Blacks, wait until 7-9 days after 50% out of bloom.   Now researchers are saying to apply AT 50% Bloom for Stevens, Ben Lear and Early Blacks - only use the 'old' recommendations of 7-9 days after 50% out of bloom for Howes! 

How to Calculate % Out of Bloom: 

Collect 10 uprights from at least 5 areas of the field and count the # pinheads, fruit, hooks and flowers. 

   Total pinheads + fruit                                X 100     =   % Out of Bloom
total hooks, pinheads, flowers, and fruit

You should time your first cranberry fruitworm spray at the 'egg stage' - which would be at 50% out of bloom for Stevens, Ben Lear, and Early Blacks and 7-9 days after 50% out of bloom for Howes. 

Five days after the first treatment, randomly collect 50 fruit per acre  (or a minimum of 200 per bed for smaller acreages), and use a microscope to record the number of eggs.  On beds sized 1-5 acres, the threshold is 1 egg, on larger beds add 1 egg per every 2 acre increase, for example, the threshold on a 7 acre bed would be 2 eggs.   If egg numbers trigger a spray, spray immediately, if no eggs are found, continue to scout for eggs every 3-4 days until mid august.   

Happy Counting!