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SWD control 2024
Updates on organic SWD control
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rabbiteye
10 Posts
(Offline)
1
May 5, 2024 - 7:48 am

New poster here.  I'm a commercial organic fruit grower in the southern Willamette valley.  

Just wondering how folks have been faring with SWD the last few years.  We started getting decimated with our brambles about 14 years ago and have struggled with the pest mightily.  The only thing that has helped are spinodsads (Entrust) sprayed weekly.

What I did want to share though is I've been working with Vaughn Walton at OSU with a couple of things.  First, he was kind enough to provide me with his innovation that they are having manufactured:  "Decoy".  And second, we were able to receive two Ganaspis wasp introductions on our farm.

First let me tell you how Decoy worked for us.  Decoy is a small tablet like a sugar candy that smells like sweet cherry.  When kept moist it attracts SWD who stay on it and lay eggs.  Place on a 40' grid it theoretically can level out population spikes for SWD.  We first started placing DECOY during sweet cherry and raspberry season.  We didn't notice any favorable results....at first.  What I realized was that just wetting the tablet with a watering can was not sufficient.  They table remained hard.  SO we started placing the tablets in a small paper 1/2 oz sampling cup and filling it half way with water (to which we added 1 drop of Entrust in a quart watering jar.  The results were amazing.  We were able to get away form weekly Entrust sprays in strawberries for several weeks during June and july.

But finally when the himalaya blackberries were about 3/4 of the way done in mid August the huge population of SWD breeding there overcame DECOY and we had to resume Entrust coverage on susceptible fruits.  This year we want to get going earlier with Decoy.

Now, the part I'd been waiting for....well, just about forever.  We were able to finagle a Gansapis brasiliensis release on our farm.  Actually two releases.  The first from Vaughn Walton, and the second for the USDA.  Both brought out by a grad student working with Vaughn.  We only got a total of 60 wasps released but like the old testament admonishment they were told to go forth and multiply.

The grad students were particularly excited about the sorry state of my blackberry infested blueberry patch for the release site.  Perfect cover for these delicate little pinhead sized wasps.

Anyway, don't want to go on forever but thought I would share my experiences with you.  (And by the way, I chose 'Rabbiteye' as my user name because I have 5 acres of rabbiteye blueberries. SurprisedSmileMaybe a topic for another day).

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Rooney
Vancouver SW Washington
793 Posts
(Offline)
2
May 5, 2024 - 12:43 pm

Interesting.

Possibly take a look at the many areas of the PNW for a blessing to replace the Enthrust. The idea here is native bitter cherry prunus emarginata which are highly similar in DNA to the east Asian groups of cherry land races and also where SWD originated. Upon crushing or storing parts in enclosures of our trees is the far beyond a slight notice to the olfactories! (stinks)

Spraying Enthrust sounds like it works but should this bitter cherry wood be as proposed "specially formulated" then possibly if you have the time seek the safety recommendations of whatever people (ie. Vaughn Walton) you work with of what to use as a moisture base for the spray and what to wear. Myself, have used powerful blenders for grinding up twigs and leaves of American pawpaw for eradication of potted plants of nematodes before (hos archives and posts). So if I had SWD I would have given the first idea of cherry as source material the try. 

My sources of bitter cherry, the producer of hopefully 'juglone from walnut trees and roots' like properties, are also existent as prunus x-pugetensis as hybrids between other cherry types, a few which are fast growing enough to mass cultivate for the possible purpose of this yet to be revealed substance. 

In the case of juglone as a known toxin I recently read about as to soil microbes and other trees (and apples) also has me worried enough not to plant bitter cherry near enough to other fruit trees, so in such cases a great abundance of caution is always advised!

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jafar
780 Posts
(Offline)
3
May 5, 2024 - 9:27 pm

rabbiteye,

Thank you for joining and sharing that post. I'm very excited for you.  SWD has been discouraging to my fruit raising ambitions.  We are in the forest with lots of Himalayan blackberries.  Trying to grow brambles seems pretty futile.  And the one benefit of the blackberries, the fruit, is ruined since they are leaky mush before they sweeten.

There is quite a bit of year to year variation.  I hope the wasps make it to our little corner.

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rabbiteye
10 Posts
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4
May 6, 2024 - 7:41 am

Here's an interesting tidbit on the wasps:  When I first started begging Vaughn Walton for a release on our farm he mentioned that he wouldn't be surprised if we already have them!  OSU has found them already occurring naturally in various locations in Oregon and Washington.  But there are some issues with G.b. ; 1. Is they tend to lag behind SWD in the early summer build up.  At best Vaughn figures that the parasitoids are just another helping hand but not a cure-all for SWD.

If you want to figure out if you already have parasitoids at your location you can do the following (this info courtesy of Vaughn's grad students who are charged with monitoring and rearing):

About the time your Himalayas start getting infected gather up a few pints of infected fruit and place them in a 5 gallon bucket.  Have some humid potting soil (about an inch or so at the bottom of the bucket for the fruit to sit on).  Cover the bucket tightly with a super fine cheese cloth and tape down the rim and store the bucket in a darker controlled temp area trying to keep the temps around 60-75F.  Wait for up to a month to see if you get little wasps to emerge after the SWD do.  It is key that the top be of a material that is not so porous that the wasps can escape.  They are very tiny.

I think they will be coming back this year to trap for parasitoids here after their initial release.  If not I'll be trapping myself to see if the releases took hold.

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Rooney
Vancouver SW Washington
793 Posts
(Offline)
5
May 6, 2024 - 10:46 pm

rabbiteye said
...  At best Vaughn figures that the parasitoids are just another helping hand but not a cure-all for SWD.

...  

Parasitoid Wasps and the various methods found inside plants to function in similar fashion to a magnet to attract these Parasitoid wasps:

L‐DOPA functions as a plant pheromone for belowground anti‐herbivory communication

Not even perfect plant health and a perfectly optimized communications system is a perfect " cure-all for SWD " either. Consider the necessary elements needed (and if possible get them) and 'engineer' them into a corner of your farm to test operate these principles as a trap crop.

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John S
PDX OR
2834 Posts
(Offline)
6
May 7, 2024 - 8:33 am

I have been growing a lot of carrot family plants, not just due to the pollination but also for the attraction of positive insects.  The parasitoid wasps are attracted to them, as well as syrphid flies, lacewings, minute pirate bugs, ladybugs, etc.  I have different levels of plant heights, which an entomologist told me would attract spiders.  Hummingbirds like to eat small insects.  Rampant diversity harbors predators of such insects. I don't sell fruit so a bit of extra protein doesn't bother me too much. I freeze a lot of my pie cherries and some blackberries.   I also use clay drenched fruit sox on especially vulnerable apples. Sturmer Pippin is my most fruit soxed apple. Great keeper but vulnerable to bugs.

John S
PDX OR

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rabbiteye
10 Posts
(Offline)
7
May 7, 2024 - 10:38 am

Good stuff there John.  By default I have a lot of diversity around our farm as we grow certified organic and our 13 acres of certified ground is surround by another equal amount of wooded or idle ground that we own.  We do some plantings of phacelia and crimson clover for mid-late summer pollenizer foraging.

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