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EAS as thinning 'ally'

Posted by Josh Karp 
EAS as thinning 'ally'
May 22, 2017 03:38PM
Ok, a bit provacative here but: many of us have some European Apple Sawfly pressure. With a huge bloom currently underway, I'm wondering about using these guys to do some thinning for me. Of course the question is , in their exuberance, will they overdo it. But, if we're supposed to thin 90% of the fruit anyway, what are the odds they would overthin?? I know, par of the answer is that 'it depends on your EAS pressure' . In my case, having managed it for a long time, the pressure is low-moderate. Put white sticky cards out there at pink, caught some but not tons, no more than 8 per trap.
If I could come up with a metric, i.e. trap threshold of i.e. up to 8 catches per trap is the perfect thinning population, more than than = maybe need to spray 'em instead.
This is kind of tongue-in-cheek but am also seriously wondering. For those of you who DON'T manage for EAS, how many of you lose a huge % of your crops due to this insect, in a big EAS year?
Re: EAS as thinning 'ally'
May 26, 2017 06:31PM
FOR SALE: Trained sawflies able to distinguish proper spacing of fruit on apple trees. Will sell only to young and upcoming farmers in northern Vermont. Each of these sawflies comes with a certificate of rigorous training from the USDA-Monsanto division. Guaranteed results!

The rub, Josh, is that each female EAS lays one egg per blossom cluster along with a chemical cue telling other females to go to the next blossom cluster. Highly efficient egg dispersal going on here. The resulting sawfly larvae is in turn quite capable of eating the seed cavity of several fruitlets. The net result is no fruits on branches from the outside in. Crop loss in this case is not about spacing prospects but rather the best potential fruit with full sun exposure. The other thing about letting EAS run amuck is that far more larvae will reach the soil to come back the next year.

I am seeing moderate trap presence but will gauge fruitlets at pea-size. I just have to find a few winding trials in process on those fruitlets to know a dose of spinosad in the Spring4 application a week after petal fall will be a good call.

Lost Nation Orchard
Zone 4b in New Hampshire
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