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Thanks for the advice everyone. What a wealth of knowledge! Seems we will
be ready next year with beneficial insect habitat plantings, and if
necessary, a diversified spray regime including Rango, Mycotrol, and
Surround. Maybe this is in the works, but if anyone has time to run a study
on the use of beneficial nematodes for control that would be greatly
appreciated.

Thanks again,

Carl

*Amendment to Original post: We have been rotating Entrust and Pyganic. *
*Original Question: We are losing (lost?!) our onion crop to thrips this
year. We use silver plastic mulch,  had well timed applications of Entrust
+ Biolink at 70+ PSI. In the past we have achieved control with Entrust. We
are guessing the population has developed resistance and that the pressure
this year is beyond what we've ever experienced. We would love to hear
others' strategies so we can be prepared for next year. *

*Thanks, *

Carl

Responses:
1. I have a similar experience using silver mulch and Entrust, though it
sounds like our overall damage wasn't as severe in the end.  We were
certainly helped by some overhead irrigation early and hard thundershowers
later in the planting.  I also wonder if I am seeing resistance, and would
love another alternative material for rotation.  I've tried Des-X soap and
oils before with little apparent success.  I have noticed that our late
yellow onions with more robust leaf growth fare much better than other
cultivars with fewer, slimmer leaves, given the same silver mulch + spray
treatment.
2. That is a bummer. Some advice (regarding western flower thrips and not
onion thrips) we got from Caleb, Jason, and several growers was to increase
beneficial insect habitat both on field borders/hedgerows and within
plantings. Not sure if that would help for onion thrips also? We are
planning to start by using sweet alyssum transplants either directly in the
cash crop or in harvest/spray lanes (essentially turning these lanes into
beneficial insect lanes) depending on the crop.
3. We are conventional, even so, thrips are a real problem. Spinosad was
long ago burned out in the ornamentals industry from overuse...in fact less
than 10 years from its introduction. Any strategy going forward organically
will likely entail something from every IRAC or FRAC group, cocktails. etc.
The strong version of Pyganic should be in the mix. We have some success
with synthetic pyrethroids. I would specifically reach out to Jack Mannix
at Walker farm to check with him if he doesn't respond.  UVM is working on
organic and biological thrips control so hopefully in a couple of years we
will have another tool.

If you have significant damage at this point, I am not sure there is
justification for further spraying, they are likely inside the leaves as
well. My condolences. Been there, done that....

4. That sucks Carl, sorry to hear it. For what it's worth, we're getting
good natural control by planting a lot of alyssum to attract hover flies
(and perhaps other predators of thrips that I'm not familar with). We only
have 3/8 of an acre of onions and shallots, blocked in 50 foot beds, but we
transplant a sweet alyssum at the head and foot of every row. We are
modeling that practice after Frith Farm, who also gets a good crop without
having to spray. They have even more pollinator habitat developed than we
have.
I think some people direct seed alyssum in line with the crop when they
have long rows. It wouldn't interfere with cultivating if it was in its own
bed.

5.We tried silver mulch for a few years but switched to white. Last year
and this much reduced thrips but it could be the weather, hard to know yet.
Last year we did a comprehensive spray program which included entrust,
m-pede, pyganic and a spreader sticker, had excellent results. This year I
only sprayed once but included Rango, a new neem product in the mix and no
m- pede, again excellent results and the few thrips I saw were dead.
Starting to harvest today and all varieties look very good with no disease
present. Good luck,onions can be a heartbreaking crop of nominal profits
Howard

6. We have used Surround successfully.

7.Wicked pricey, but Proteknet works. The onion tops push up against the
cover but it doesn;t seem to bother them. I can get 2 years out of a piece.

8. IPM labs has a nematode they recommend spraying for thrips.  I ordered
some this year but haven't made time to spray them...oh well.  Maybe a
thought.
Best to all at GF.

9.We have a customer trialling nematodes for onion thrips in outdoor
onions. We do have a history of very successful control for many years
under a high tunnel in Minnesota, at first an acre, but later .6 acres
because the onions got so large that they cut back the area under
production. A conventional grower who never went back to pesticides.

10.So sorry to hear about your thrip problem.  We use Surround. Here's the
article my husband Tom wrote for the MOFGA paper about thrips.
https://www.mofga.org/resources/onions/onion-thrips/

11. Overhead watering can suppress populations, don’t plant near grain,
alfalfa (other legumes), or cucurbits. Beauveria bassiana (Mycotrol ESO)-=
when populations just start, pyrethrin.

12. Good chance to run a variety trial next year! I can pretty much
guarantee we run grower trials in alliums every year now. What varieties
did you grow this year? and did you see it as bad across your whole crop or
worse on some varieties.. ?



We get thrips pretty bad up here at Johnny’s too. John Navazio has been
selecting for thrips resistance on his onion breeding material too so might
be able to work with him also..