I took this photo last year on March 31st, intending to post it on this blog to show the get-up I had devised for disbudding and disposing of thrips-infested rose blooms. Turned out to be just too devastating to my fragile self-image, so I never used it. The season of thrips (the word is both singular and plural) is approaching again, and, apparently, they are a problem for gardeners everywhere both for ornamentals and veggies. The topic came up this week on The Roses Forum. It’s a very serious subject, but when I posted this photo last night, it evoked some good laughs. I’m going to quote here extensively from that thread.
The original poster, kpfl81 from Arkansas, was inquiring about the use of beneficial nematodes in battling flower thrips in her roses. She shared the results of her previous efforts to control the pests, as follows:
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.
After reading the comments that followed I decided that I needed to get on the stick to be prepared for the onslaught that will come to my garden in late March/early April. I 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 had already bought the spinosad concentrate on my recent trip to Grower’s Fertilizer. It’s equivalent to Monterey spray (5% concentration), so that's what I will use, spraying the whole bush especially the undersides of leaves. There is also a Fertilome product that contains spinosad. It works because the thrips feed on the leaves as well as on contact. 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 in the late evening or early morning when bees are not around, and I don't intend to get it on open flowers or on the flowers of companion plants. Meredith in NC “does it at night and also pulls off all the open flowers on the sages, etc. under the sprayed rose.” 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.
I do not spray chemicals so this is a big deal for me. For the last two years I have been disbudding and deadheading the whole garden once I see that the thrips are here which did stop the repeated generations. My understanding is that the adult thrips inject their eggs into tiny, new flower buds where they grow and feed on the flower, damaging the flower at the very least and at worst preventing the flower from opening, called balling. Hopefully, killing the adults before they can accomplish this injection will protect the flowers. Typically, thrips favor light-colored roses, but last year red roses were effected. ‘Louis Philippe’ was decimated, even ‘Mrs B R Cant’ which in previous years was not bothered. Most of my roses are light colored & pastels. Not only is it disheartening to remove the whole spring flush which is the best of the year, 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, as shown in the photo. It usually takes two or three bags to get the job done, 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.
** 2/2/2013 - My Plan has been revised. Thanks to a very accomplished rosey friend I have new information on dealing with flower thrips that I need to include in this post. She suggested Saf-T-Side horticultural oil. She uses it to keep the thrips population under control and says it's cheap, doesn't burn except in the hottest summer temps, and is very friendly to beneficials. I did some investigating myself last night and found that she's right, of course. I wondered why such an easy, non-toxic remedy wasn't mentioned anywhere else in my searches for an answer to thrips - or maybe I was only looking at the chemical remedies. You can read about it HERE. As I was thinking about it last night, I became concerned about getting the spray on flowers because the oil damages them, and the whole point of spraying anything is to prevent damage to the blooms. Then I considered the timing. In two or three weeks I will prune (though not all of the bushes get pruned), so they will not have flowers or even much foliage on them. (Hmm, I'm recalling Dr. Malcolm Manners' practice of stripping leaves on all of his roses at pruning time.) The roses will be leafing out and setting flower buds during the weeks after that, and that's when the thrips arrive - just in time to hit all that tender new growth. I think that will be the time to spray the Saf-T-Side. There doesn't seem to be much difference to me between the Saf-T-Side and the spinosad except in their toxicity to bees which probably amounts to a huge difference ecologically. This spraying business is definitely a reach for my inexperienced brain. Gardening is surprisingly full of new experiences, and I'm trying not to lead you all down the wrong path - again. The main point is that if you are producing beautiful roses with what you are doing, keep doing it!
According to Wikipedia, “Spinosad is considered a natural product, and thus is approved for use in organic agriculture by numerous nations. Two other uses for Spinosad are for pets and humans… Brand names include Comfortis and Trifexis® …both brands treat adult fleas on pets.” Here’s another good article from the University of Connecticut.
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.
There is another product called "blue sticky thrips traps" that is available online. The thrips are actually attracted to the color blue. The sticky strips really are more of an early warning system than a cure. They clearly declare, “They’re baaack.” I'm also going to make my own "blue sticky traps" out of the large blue plastic drinking cups coated with vaseline and hang them throughout the garden. Lovely. Last year I used some kind of automotive lubricant (forgot the name) which was nasty to apply, but the vaseline will be much easier.
In learning how to grow roses organically I have become convinced that insecticides are a double-edged sword that can produce unintended bad results. For instance, using insecticides against spider mites produces worse infestations because they kill the beneficials that would have handled the mites had the gardener used a hard water spray and awaited their arrival. Something that we don’t realize sometimes is that insecticides kill ALL insects. ‘Broad spectrum’ is the term that’s used. Since there are beneficial insects called predators that gardeners want to encourage to inhabit their gardens, it is absolutely counter-productive to spray these broad-spectrum insecticides. And perhaps you’ve heard of the devastation to bee populations in recent years. As far as I'm concerned, the bees are a protected species and are welcome, friendly guests in my garden. I love listening to their buzzing as I go about my work in the garden. So let's be safe out there and kind to our beneficial bug friends.
My afore-mentioned laughs came from Merlcat’s response to my photo which I must include:
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! :)
Aren’t gardeners wonderful?!
To read the entire thread on GardenWeb's Roses Forum, go HERE.