Thrips in the Garden: Damage and Control 

Thanks for the feedback and support

Thanks so much for your encouragement and support!

Jason once again, I think you have walked in my garden! I didn’t know what was ruining my flowers until I watched your video this morning. Thrips have destroyed so many of my Dahlia’s and flowers and left me with sad/dead blooms and leaves that are lifeless and crispy. Thanks again for sharing your knowledge and advice. You are someone I rely on for sound garden advice.

I'm so pleased you found it useful!

Laura at Garden Answer just used a Drone to cast Preditory insects last week

That's so cool!

Most welcome!

Thanks for the encouragement!

My pleasure

My roses have black spot this year 😢

My pleasure. Thanks for watching

Wow - what an interesting project to raise your own! Props

Thanks!

Thanks. I have a much older video on the topic: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-mI5zowOac6I.html

Some thrips do have a life-stage in the soil, so something like steinernema will cut their numbers. The downside in comparison to something like cucumeris is the cost - the nematodes are far more expensive to apply last I checked.

That sounds about right - it's near impossible to wipe them out entirely with sprays! Best luck in your fight

Thanks for sharing your experience - definitely more challenging in a warmer climate. Here I can often "ride it out" with little or no intervention

Sure. Maybe I'll make it a video topic, but in the meantime it's really just a matter of hanging them (by twine, twist tie, whatever) into the foliage canopy of your plants. The yellow or blue color attracts the pests when they're abundant, and they stick to the surface. You come back every week or so and inspect the cards - if they're clean, it sets your mind at ease. If they have loads of thrips or other plant pests, you can start looking for signs of damage on the plant and decide according if it's worth adding beneficials or taking other measures.

@@FraserValleyRoseFarm Thank you! I did see some yellow cards and some blue ones online, and I wondered which was better for thrips. Sounds like either is fine. Some of the reviews say small birds can get stuck to them, too. But it's hard to know if that's true or not. Yes, a video would be great.

Thanks. Not so much - it seems to be the pests flying around looking for yellow leaves that are being trapping in high numbers

​@@FraserValleyRoseFarm The same with me. I only have the white Honor rose that really attracts the thrips as far as roses go, but the tomatoes, strawberry, and any other non-smooth leaf plant seems to be attracting them now that the temperature is warmer. Fortunately for me the nights are already starting to cool which is definitely keeping them from multiplying very quickly like down at the lower elevation. On the coffee farm the thrips were impossible to control even with biological beneficials. I just clipped the affected areas and made the best of it because here in the tropics it's a year round problem. The rainy season slows the down for a month or so and that's it because the temperature is rarely below 15C/60F unless you are above 1,000m/3,000ft elevation. Sprays and powders are completely useless, although many people use them think they will do something, but the don't. Unfortunately many pest control companies encourage treatment, but it is a dishonest game.

Thanks for those insights!

I've had issues with beneficial mites sticking to the sticky traps (I'm using them for fungus gnats) in a green house/container plant setting. The mites tend to love to circle around the pot edges and since the traps are touching the edge of the pot they do tend to walk into it frequently. I may remove the sticky traps initially next time when the mites are fresh and at their most active.

I think horticultural oil is the best recommendation

So sorry to hear it! I've generally gone with the loose bran, so I can split it up and spend some time on careful distribution to all the effected plants.

Hi! Do you mind giving some details like the ratio of glue to water and how and when you sprayed? This could be useful to me!

@@petramckean5041 sure! I use 1/2 cup of Elmer’s glue, next I add 1 teaspoon of cocoglycoside surfactant ( I use this because sulfate based or phosphate based anionic surfactant is toxic to leaves) or you can use any nonionic soap, then I mix until the two become a thick creamy paste. I add enough water to dissolve the paste and pour into 1 gallon of water. I shake it to homogenize it and I apply on top and bottom of leaves when the sun is setting so that it has the night to dry off and form a film. A more expensive polymer for agriculture and winter protection is Antistress 2000, or Floralife’s Crowning Glory spray. I do want to give a fair warning: some rose petals maybe discolored if sprayed under direct sun, the coating also mutes the scent of roses. It also masks the leaves from insects and fungus.

@@petramckean5041 I would also like to add that if this is the first time your roses are being treated with this, I would start off with a test spot at a lower concentration (dilute into 2 gallons) since each rose is slightly different with different thickness of leaves. As a rule, I always let new leaves mature and harden off before spraying. Spidermites like to work their from bottom to the top as the bottom gives them more protection.

Sure. Have a look at this one: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-4FicmVqT_a4.html

Nematodes can be helpful for controlling thrips that spend part of their life cycle in the soil (not chilli thrips, though). Feedback I've heard from other growers is that the fungi treatments are not strong enough in their effect to manage a full-blown infestation. I haven't looked into the chitosan treatment.

They'll find it!

Timing can have a lot to do with it. We tend to have about a month in the summer where the temps are higher and they roll through our rose field. As the temps subside the predators are also beginning to catch up. As mentioned by other commentors, this is not a certainty in warmer climates where the higher temps give thrips the upper hand over a much longer period.

@@FraserValleyRoseFarm Thanks!

There are pros and cons to each approach. Even with the initially more effective chemical methods, pests like thrips are not entirely wiped out, and it leads to strong selection pressure for resistance. I recently looked up the emerging resistance to Orthene on cotton thrips: it was seen as the best control, but it's started now to become progressively less effective from repeated application. That's not something that happens with biological controls, but they have their own application issues. I won't judge other growers for how they manage the problem, but I know applying toxic chemicals isn't for me for a variety of reasons.

@@FraserValleyRoseFarm : well, that's where detail and up-to-date research matters on any compound, on a one by one basis. certainly is complicated. any compound, natural or synthetic, can be problematic or toxic. that's why i no longer believe in this human invented distinction to signify much of anything. we've been inadvertantly breeding out pest resistance, by selecting more showy and more edible crops, that we want to produce in a scale and in places where they dont naturally grow by themselves in abundance. the universe/nature has no special plan or balancing acts with specific goal. the most pest/disease resistant roses are original plants that nobody would plant in their garden. copper, arsenic, sulfur, phosphorous, all occur naturally in some places and are deadly in those (natural) concentrations. animal manures are high in sodium. it's a balancing act on our part. there's too much organic good sounding stuff, but unfortunatelly not backed by sound science. but since i can easily get rid of weeds by regularly weeding, as i dont have a commercial farm, i dont spray any weed killing chemicals. the funny story is how we have minimum size specified for catching fish, which ironically is making fish populations evolve to smaller growing fish, as undersized mature fish start to dominate the gene pool. i dont have an answer to fix that, and i stick to the minimum size rules, despite their shortcomings.

Yes, nematodes ae helpful against the stage of the lifecycle where some thrips (not chilli thrips) pupate in the soil.

I'm not sure about the regional suppliers, but I've even seen them listed on Amazon.

Another one to consider might be spinosad - it's one the safer and more natural side so far as insecticides go. Yes on the insecticidal soap!

Yes, much more difficult indoors (or even in greenhouses) than out in nature where they have loads of predators. The cucumeris mite is still a good option indoors if you can find a handy supply.

I tried Swirskii mites this spring for the first time - I suspect they did work, but they need a constant supply of things to feed on or they die out. So as soon as their population dwindled I had a thrips boom again (currently in it now). I have a feeling you'd have to have a regular addition of mites every couple of months ad infinitum to solve the issue, which gets expensive and they don't ship them in the winter months. All I can think to do at this point is check every leaf on all of my 100 or so plants every 2 days and hopefully eventually I'll kill them all. Such a bummer! I hope you've had success in your situation - I had never heard of thrips until last year, and now everyone seems to be talking about them. Are they spreading/growing or just more awareness do you think?

I'm quite sure it's a matter of awareness - they've been a serious concern in agriculture all along

makes sense! thanks for your replies ☺

It varies by region - but even a quick Google "shop" search for cucumeris may give you an idea of options. The best time would be early in the infestation, so sticky cards for counting/monitoring can be really handy. But no worries if you missed their first arrival - you can take action now if warranted, and also note the approximate date for next year so you can get going earlier.

Thanks - polyantha roses are really quite like floribundas and other modern roses. It can make a difference if you're growing in the ground or a container. In a container, I like something like a 16-10-10 slow release (rate as directed on package). In soil I tend to go with more organic amendments like alfalfa pellets or manure. You can also top up with a liquid feed of something like fish fertilizer for a boost in nitrogen.

it's in the ground. am i allow to use ferterlizer when the bulbs show color?because i know it will shorter the number of blooming days of the ROSE.but some bulbs have color some just start as a mini bulb ,then i don't know what to do.@@FraserValleyRoseFarm

The timing is not critical - adding fertilizer or organic matter to the soil is a matter of feeding the soil microbes, which then over the long term make the nutrients available to the roots. That'll support a healthy plant. Healthy plant = better flowering. Don't worry about the stage of the flower buds.

That's rough - another crop they really impact in a bad way