Thrip Control

kpfl81January 29, 2013

I'd like to hear some feedback regarding the use of nematodes to control thrips. For the past four years, I've had a devil of a time with thrips. Most of what I have tried has met with limited success:

1. Tried insecticidal soaps & neem oil -- hardly any effect.
2. Bifenthrin & imidacloprid - marginal results.
3. Spinosad -- marginal.
4. Orthene -- this works; however, I have to apply almost every five days in order to keep the scoundrels down. At that rate, I start worrying about the health of the roses. Additionally, the Orthene smells so foul.

I feel like the time to strike for this season is now; however, I'm at a loss as to what will work. Nothing angers me more than seeing a big bloom open prematurely and sickly because of a thrip.

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nanadollZ7 SWIdaho(Zone 7 Boise SW Idaho)

I tried some of kpfl81's remedies, including spinosad, with no improvement in thrips' control. I didn't try Orthene. What I finally used that worked pretty well is a granule form of imidacloprid applied around the base of the affected plant and scratched in. I did this on a very limited basis, strictly on plants I knew were thrips magnets. The maker of this insecticide is Hi-Yield. Diane

    Bookmark   January 29, 2013 at 2:38PM
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Thrips can all but destroy a beautiful spring flush. I don't grow roses to feed the thrips. Especially after waiting all winter for some beautiful roses. Example: Moonstone. Do I want those big beautiful white tipped in pink blooms or do I want nice long stems with beautiful foliage and a ball of mud on the end. I'll do whatever I have to do to make sure I have good looking blooms. Orthene for 6 wks in the spring. It's your choice. Now if the nematodes work, I need to know.

    Bookmark   January 29, 2013 at 3:26PM
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lola-lemon(5b East WA)

I had a heck of a problem with thrips last year because I brought home an infested plant from a nursery (should have paid better attention to all those unopened blooms!) and didn't have enough time to treat it before I left on a month long vacation. Just one shot of spinosad.
Once those suckers get established they are dang near impossible to get rid of. that's also what the literature says. They spread to every flower on my property (they LOVE LILLIES of all colors, and Dianthus, and sage and... and ....). If you didn't know which plant was the original offender, you could have easily guessed by counting how infested the other plants were on my property. It was like a bomb (center zone red, then the orange zone, then yellow .... UG) those nearby were FULL of them, the furthest away were just getting impacted.
Anyway- I tried everything and I found that if things weren't too bad you could use a really nasty spray like orthene dutifully and get rid of them. But if they were everywhere, it took a more thoughtful approach. I can't be drowning my entire property in orthene. I'll get rid of flowers before I do that because you wreck all the natural habitat for any good bugs and you are forever stuck fighting everything.

anyway----What ever you plan to do- start yesterday and don't quit.

Here's what helped for me.
Nematodes- yes, definitely. I will use them always. I think I got a mix of nematodes.
helpful bugs: the most useful bugs for thrips also bite people and I didn't want my child being bitten so I used lady bugs and praying mantis to little effect. The lady bugs flew off to my lilacs (which they cleaned, thank you) and the praying mantis took forever to hatch. There are better bugs (pirate??)
I also used blue sticky traps and they caught thousands. I put many of those traps out and watched them fill up like a pile of whisker shavings.
I also sprayed a natural insecticidal soap (where the nematodes weren't ) every other day. And I removed almost all my blooms all summer. (sooo hard to do).
the soap helped keep new adults from laying new eggs.

I barely got some form of control at the end of the summer and I hope this winter has killed them, but I will start early with nematodes and lady bugs hoping to nip it in the bud.

I also will NEVER bring home nursery roses again unless they are from the rose seller here that I know NUKES her roses regularly and does not grow them in greenhouses (they are basically impossible to eradicate from greenhouses). I am mostly getting bareroots from now on though because the thrips come in the soil too. horrible little monsters. I told the nursery who sold me the infested plant about it and she said she thought thrips were only a nuisance and nothing to worry about as they don't kill plants, only prevent flowers. !! ( She sells plants, not flowers.)

This post was edited by lola-lemon on Tue, Jan 29, 13 at 17:30

    Bookmark   January 29, 2013 at 5:10PM
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buford(7 NE GA)

I never had thrips until I stopped using the Bayer drench. It's overkill for most of my roses, but for those that are ruined by thrips for most of the season, I am going to use the drench on them.

I also bought this spray, I think it's a fungus or maybe nematode that is supposed to control thrips. I will try it this year on all of my roses. Even the ones that don't get damaged are usually crawling with them.

    Bookmark   January 29, 2013 at 7:06PM
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Maryl zone 7a

Thrips are everywhere. Although it seems as if all the Thrips in the world are concentrated on your rose blooms, I assure you that unnoticed by you there are Thrips feeding in the acreage all around you. Kill the Thrips you have on your rose blooms and other Thrips will quickly move in to replace them. Thrips are also cyclical. They are always around, but some years their numbers are worse then others. Thrips pupate in the soil around the rose they are feeding on, so disturbing the soil under the rose may help kill some of the offspring. Some roses are more attractive to Thrips then others, and some roses will show Thrips damage more then others.....What you are smelling when you apply Orthene is the additive Mercaptan, which is a "stinky" organic substance used in gasoline and many oil products. It is basically harmless but the smell is there to alert people that what they are using can be dangerous and to pay attention...I gave up trying to kill thrips by chemical means years ago. It's not that I'm against responsible spraying, but nothing I used had much effect. If I heard of something that REALLY worked and wasn't going to nuke every living creature in my back yard at the same time, I might consider it. But barring that I have reluctently gotten rid of the roses that the Thrips seem to have on their favorite menus. I now have only a few light colored roses, and those I kept have fewer or looser petals so that the Thrips can't hide as well in between them. They don't seem to care for an open bloom as much as a closed bloom. There are exceptions. Tineke is a great white that seems not to show the Thrips damage as much as most light colored roses if the Thrips pressure is low to moderate. Last year after a warm winter, even it looked pathetic during spring bloom....I know you are looking for the magic bullet (who isn't), but so far I haven't heard of anything that works over the long haul....Maryl

    Bookmark   January 30, 2013 at 2:37AM
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I'm thinking of covering those flowering buds with brown plastic bag... or place a net over my roses. I'm also going to put lots of yellow sticky tapes . I hope one of those methods will work..I was very heartbroken when all the buds had been completely destroyed by those throps. None of them had open up completely. They turned yellow and died.

    Bookmark   January 30, 2013 at 5:51AM
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I just did some research online, prepared to buy the nematodes. Found out it's expensive to ship, and since most of the thrips are on leaves, the soil treatment is not very effective. Apparently, in Florida they love oak leaves, and I am surrounded by oak trees. I already bought the spinosad concentrate locally equivalent to Monteray spray (5% concentration), so that's what I will use, spraying the whole bush especially the undersides of leaves. It works because the thrips feed on the leaves. It is safe for bees once it is dry in a few hours. It is toxic to bees when wet, so they say to spray until drippy in the late evening or early morning when bees are not around, and I don't intend to get it on open flowers. Spinosad loses its toxicity after 8 to 24 hours and so it may be necessary to reapply a few days later if new larva hatch. (Please note that I originally wrote that it was effective for 3 - 4 weeks, but I found out that was wrong.)

I do not spray chemicals so this is a big deal for me. I have been disbudding and deadheading the whole garden once I see that they're here which has stopped the repeated generations. Last year red roses were effected. Louis Philippe was decimated, even Mrs B R Cant. Most of my roses are light colored & pastels. Not only is it disheartening to remove the whole spring flush, but it is painful, backbreaking work. I look like a cotton-picker with the trash bag (taped to a large-mouth jug with the bottom cut off) tied to my waist. It usually takes two or three bags to do the job, and when they're full, they're heavy. So I'm going to try the spinosad. I'm told that the thrips are here year-round, but April is their big breeding time. The rest of the year isn't bad, but it does explain why my blooms are never quite perfect with their brown-tinged edges.

Imidacloprid also works (it's in the Bayer drench), but it is systemic and kills bees because it gets in the pollen. REALLY, YOU SHOULD NOT USE IT (and other systemics) for the sake of the bees. The spinosad is also effective against grasshoppers and other bugs that chew on your leaves.

I'm also going to make my own "blue sticky traps" out of the large blue plastic drinking cups coated with vaseline. Last year I used some kind of automotive lubricant (forgot the name) which was nasty to apply, but the vaseline will be much easier.

Let's be safe out there and kind to our beneficial bug friends.


Here is a link that might be useful: If only sweat were irrigation...

This post was edited by sherryocala on Fri, Feb 1, 13 at 12:08

    Bookmark   January 30, 2013 at 1:04PM
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meredith_e Z7b, Piedmont of NC, 1000' elevation

On spinosad, I've used the Fertilome product ( ) with fine results around my precious bees. I don't quite spray till drippy, but I have sprayed until I can see good foliage coverage with a fine mist.

I haven't used it for thrips, but I don't use systemics because of bees, so I think the spinosad is probably better around them. One thing I do think I noticed is that the leaf-cutter bees may have been affected (once) by my using it. Now I absolutely won't spray it near their favorite haunts. I don't know the research on that, but I think maybe they shouldn't eat the leaves even days later if you use this product (or similar).

And make sure your companion plants aren't attracting them when you spray it. I do it at night and also pull off all the open flowers on the sages, etc. under the sprayed rose. I leave the bee flowers about 8-10 ft away, and the bees do go to those flowers the next day with no noticeable ill effects. HTH. I hate to use insecticides!

    Bookmark   January 31, 2013 at 5:30PM
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"... with the trash bag (taped to a large-mouth jug with the bottom cut off) tied to my waist."

Thank you, sherryocala! :)

I can't add any info about thrips, however I want to point out that the above is an excellent idea. I can totally see me using a version of this for other tasks in the garden.

I know I can use this for collecting seed heads, random small cleanup. etc.. I am always trying to keep my hands free and messing around with grocery bags doing these things, so this idea could really fix that.


    Bookmark   January 31, 2013 at 8:59PM
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You're welcome, Merlcat! You know, when I was deadheading echinacea, I never thought to use this bag thing. Duh.

Meredith, I also didn't think about the flowers on companion plants. Good thing you mentioned that.

Sorry the photo is such a mess. Couldn't get a very good shot in the bedroom mirror.


Here is a link that might be useful: If only sweat were irrigation...

    Bookmark   January 31, 2013 at 11:38PM
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Sherry, you are so sexy in that Garbage bag. How does your husband resist you? I'm just kidding, and your outfit is far more attractive than some of my get-ups.

    Bookmark   February 1, 2013 at 9:16AM
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It's the bungee that pulls the outfit together.

Bungee bling?! :)

All jokes aside. I love this picture. This is how beautiful gardens are made. Getting dirty and wearing garbage bags and bungees! :)

    Bookmark   February 1, 2013 at 9:26AM
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I love you guys. You're so funny. Sexy, bungee bling. NOT!
DH calls me "Field Hand". Such a tender guy.

I think this topic warrants a blog post on several levels.


Here is a link that might be useful: If only sweat were irrigation...

    Bookmark   February 1, 2013 at 10:42AM
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Merl, your fashion sense is amazing. It is the bungee bling that makes the outfit! I must get me some of these. I always like to be fashion-forward while gardening. Do they come in colors?

    Bookmark   February 3, 2013 at 1:04PM
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Thank you! Yes, they totally do come in colors: solids, stripes and a wide assortment of sizes! Even different color coded end hooks, plastic and metal. Ones small enough to wrap around your ponytail to keep your hair up. (Yes, I have done this)

In my past life I was a vendor on Grateful Dead tour, which evolved into vending my work at various large music festivals all over the country. My whole display was built of bungees, ez-ups and spring clamps! My stockpile of bungees and clamps is huge. They fill at least 2 of those big plastic storage bins you get at the big box stores.

I will say I have been know to wear both bungees and clamps. Spring clamps hanging off the tails of my shirts clamped in chains and bungees round my neck at the ready to build the booth.

During those said shows I would be found with at least a dozen clothes pins clipped to my fanny pack and shirt tails. Also high fashion.

I might not be the best rose gardener (yet, I am still hoping..), but give me a box of bungees, clamps, a couple tarps and a few poles and I could build a shelter that would survive hurricane and snow, and remain standing till the sun came out, for sure.

A spare roll of duct tape and some zip ties are always handy, too.

With all my past experience I know I could whip up an excellent PVC and plastic Hoop house greenhouse. Unfortunately I have not one square foot of available space to do so or I would have already done it.

    Bookmark   February 3, 2013 at 1:41PM
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Personally, I'm most proud of the fashion-forward Okabashi sandals and white socks.

Also, I've changed my mind about the spinosad for the thrips. I'm going with Saf-T-Side horticultural oil.


Here is a link that might be useful: If only sweat were irrigation...

    Bookmark   February 3, 2013 at 3:20PM
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Wow, Merl, I'm impressed. I have the space but not the talent. The socks and sandals do make quite a statement, Sherry. You should be proud.

So far thrips have not been a problem for me. When I first started gardening years ago, Elina had them. I sprayed her one time, and that was it. I guess I better knock on wood. I'm especially terrified I will get chilli thrips. Being isolated like I am, I'm hoping they won't find me.

    Bookmark   February 3, 2013 at 3:53PM
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Well that was entertaining...but back to thrips. I know most of you hate insecticides, but after having two horrible seasons with thrips and ugly spring flowers, the last two years I used the Bayer systemic only on the roses that got the thrips. I just use it once in March, and don't use it any more than that. It completely solved the problem. I have plenty of bees, worms etc.

    Bookmark   February 8, 2013 at 12:16AM
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buford(7 NE GA)

That mirrors my experience socabeth. I used to use the drench and never had thrips. But I stopped using it a few years ago and now have a horrible thrip problem. I am going to use the drench on a few roses that are absolutely ruined by thrips and other non-pesticide methods on the others (just to lower the thrip population in my yard).

    Bookmark   February 8, 2013 at 8:12AM
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buford -drench? never hurd of it- please define

    Bookmark   February 8, 2013 at 4:04PM
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