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.
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.
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
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.
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..