Roses forum: Rose Slug Sawfly Revisited

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Name: Frank Mosher
Nova Scotia, Canada (Zone 6a)
Lover of wildlife (Raccoon badge) Birds Roses Clematis Lilies Peonies
Region: Canadian Photo Contest Winner: 2017 Million Pollinator Garden Challenge
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fwmosher
Jan 22, 2018 11:14 AM CST
Thumb of 2018-01-22/fwmosher/4a5320


This pest is well known to "Modern" rose fanciers. Having said that, perhaps there are some novice rose fanciers or wannabes, who are afraid to buy "Modern" rose bushes because of the effort required. Pity! One can buy a bagged rose bush for less than $9.95 at most box stores, supermarkets here. Chances are, it will break out in full bloom before you have to take any protective steps to "save it". You will likely be rewarded with a beautiful bloom(s)!! Take a picture of it! If you lose it, so what! Throw it out, and buy another one next year. Now, only if you want to use protective measures, and you have the time, and you have already considered an earlier post I made about "Rose Hospital Bed" (not certain if it is dead or alive-make a "Rose Hospital Bed") and you want to try and keep that rose alive, here are some suggestions. For most "modern" roses, you will have to spray, not even a question! Note: I do not use "toxic sprays" in my gardens. The problems you may face are:
Aphids
Roseslug Sawfly
Black Spot
Fungus
Japanese Beetles (I have never seen one)
June Bugs (not really a problem) and a few others.

Most seasoned rose growers spray with BTK (bacillus thuringiensis kurstak) to kill this slug, which will eventually eat all the leaves off your rose bush, if untreated. It is a natural bacterial agent from the soil. The rose slugs ingest it, and their stomacs disolve. In the picture there are two rose slugs, and a large hole in one leaf, thanks to them. Nothing new so far, except this: I have found that I can "combine" rose sprays in the same container. You can combine BTK, a standard sulpher liquid to prevent fungus, and baking soda solution for blackspot. It works, unless your weather is unduly wet and damp and cool. I use a simple hand sprayer filled with a mild soap solution to kill aphids. Can't add the soapy solution to the spray, because it will help "wash" the main spray ingredients off. Still worth the photo opportunity! Cheers.


Thumb of 2018-01-22/fwmosher/b19733

Name: Zuzu
Northern California (Zone 9a)
Charter ATP Member Region: California Cat Lover Roses Clematis Irises
Garden Ideas: Level 2 Celebrating Gardening: 2015 Plant Identifier Garden Sages Forum moderator Million Pollinator Garden Challenge
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zuzu
Jan 26, 2018 8:05 PM CST

Moderator

BTK has no negative effect on rose slugs because they aren't caterpillars. Insecticidal soap and neem oil or any other oil spray will kill them, but most of us have to resort to hand-picking because it's difficult to spray on the underside of rose leaves, where the larvae feed. I have a lot of parasitical wasps in my garden, so I usually don't have much trouble with rose slugs.
Name: Lilli
Copenhagen, Denmark, EU
Irises Roses Bulbs Hellebores Foliage Fan Cottage Gardener
Plant Lover: Loves 'em all! Seed Starter Winter Sowing Bee Lover Dog Lover Region: Europe
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IrisLilli
Jan 27, 2018 11:10 AM CST
Interesting! Thank You!
You don't know if it will grow until you try!
Name: Frank Mosher
Nova Scotia, Canada (Zone 6a)
Lover of wildlife (Raccoon badge) Birds Roses Clematis Lilies Peonies
Region: Canadian Photo Contest Winner: 2017 Million Pollinator Garden Challenge
Image
fwmosher
Jan 27, 2018 3:05 PM CST
With all due respect ZUZU, you made a miss statement there! BTK is absolutely the natural very effective treatment for Rose slugs - not even a question! Spray once, they are gone in three days or less. They consume it, and it eats out their stomach within days. It is also extremely effective in killing mosquito larvae for those who have an outdoor pond. There are floating pellets available at all the chains. If one has a couple of roses, they could easily be squished, but judging by the number of rose photos you have posted, you could not possibly keep up with squishing same. Check BTK again, you have made a mistake. Note: There is also BTI, the "I" as in Isreali strain. Note: I haven't checked into the credibility of your statement that Rose Slugs are not "caterpillars.
Name: Zuzu
Northern California (Zone 9a)
Charter ATP Member Region: California Cat Lover Roses Clematis Irises
Garden Ideas: Level 2 Celebrating Gardening: 2015 Plant Identifier Garden Sages Forum moderator Million Pollinator Garden Challenge
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zuzu
Jan 27, 2018 3:22 PM CST

Moderator

Look it up, Frank. You won't find a single site saying that rose slugs can be eliminated by BTK. You will find numerous sites saying that BTK is useless against rose slugs.
Name: Lyn
Weaverville, California (Zone 8a)
Garden Ideas: Level 1 Garden Sages Celebrating Gardening: 2015
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RoseBlush1
Jan 27, 2018 4:58 PM CST
Frank, I have to agree with Zuzu. My prior research had indicated that BTK would not solve my sawfly problem.

When I saw Zuzu's post above, I did a quick Google search with "will bacillus thuringiensis kurstak kill rose slugs" in the search field. Every hit said it would not work.

In addition, until the spray dries, it is harmful to bees.

You wrote that BTK is a natural bacterial agent from the soil., which is true. The bacteria that causes crown gall in roses is also a natural bacterial agent found in the soil.

Thankfully, we now have the Internet and can do our own homework much easier than you and I started our rose lives.

I'd rather weed than dust ... the weeds stay gone longer.
Name: Zuzu
Northern California (Zone 9a)
Charter ATP Member Region: California Cat Lover Roses Clematis Irises
Garden Ideas: Level 2 Celebrating Gardening: 2015 Plant Identifier Garden Sages Forum moderator Million Pollinator Garden Challenge
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zuzu
Jan 27, 2018 6:11 PM CST

Moderator

Bacillus thuringiensis is commonly used to control caterpillars. I personally have never used it because I like caterpillars. They remind me of fuzzy little kittens. Smiling
Name: Frank Mosher
Nova Scotia, Canada (Zone 6a)
Lover of wildlife (Raccoon badge) Birds Roses Clematis Lilies Peonies
Region: Canadian Photo Contest Winner: 2017 Million Pollinator Garden Challenge
Image
fwmosher
Jan 27, 2018 7:08 PM CST
The "caterpillars" are the green rose slugs. Two pictured in the photo I posted. You should back off from, this topic, because you are best, uniformed!! Rose slugs untreated will eat every leaf of-of a rose plant very quickly. Done more research on BTK that you could ever do. It works ! By telling rose fanciers it doesn't work you are condemning their efforts. Haven't bought a rose in 30 years? Hey, let someone take over. Neam oil works on fruit trees, it is useless for roses.
Name: Frank Mosher
Nova Scotia, Canada (Zone 6a)
Lover of wildlife (Raccoon badge) Birds Roses Clematis Lilies Peonies
Region: Canadian Photo Contest Winner: 2017 Million Pollinator Garden Challenge
Image
fwmosher
Jan 27, 2018 7:23 PM CST
You have never used it but yet you can say it doesn't work! Hogwash!?? You haven't bought a rose in 30 years, you live in California, well I have and a lot of growers have, and it works!!!.. It is not harmful to Butterflies, but it is to mosquitos larvae. You were one of the first members to suggest that I had "copied/usurped" my posted rose pictures--ALL MY OWN!! Shame on you!!
Name: Zuzu
Northern California (Zone 9a)
Charter ATP Member Region: California Cat Lover Roses Clematis Irises
Garden Ideas: Level 2 Celebrating Gardening: 2015 Plant Identifier Garden Sages Forum moderator Million Pollinator Garden Challenge
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zuzu
Jan 27, 2018 7:37 PM CST

Moderator

You're misreading my posts and misquoting me. I never said I hadn't bought a rose in 30 years. I said this is the first time in more than 30 years that I haven't ordered any new roses.

Rose slugs are sawfly larvae and have no connection whatsoever to caterpillars. People who see them as caterpillars are likely to use BTK on them, but it won't affect them in any way. Furthermore, rose slugs usually will not "eat every leaf of a rose plant very quickly." I'm growing about 2,000 rose bushes in my garden. About 10 show signs of sawfly larvae damage each year, but it only affects a few leaves before hand-picking or their natural enemies (wasps, birds, etc.) make short work of the rose slugs. By relying on BTK, you may be increasing the rose slug population.

You may believe that BTK works, but you can't say you've done more research than I could ever do. I've grown roses for more than 50 years, I've done extensive research during those years, and I have never run across any source recommending the use of BTK to control rose slugs. By telling rose gardeners that BTK doesn't work on rose slugs, I am not "condemning their efforts." I'm advising them not to waste their time and effort on a fruitless endeavor.

I asked about only one of your photos, a photo contest entry, and I asked only because I found the same photo on numerous websites in several countries. The fact that I was "one of the first members" to ask about this, proves that others had the same suspicion. You assured me that the photo was yours, so I left it in the photo contest. I didn't argue with you or disqualify the entry, so why would you bring it up now?
Name: Lyn
Weaverville, California (Zone 8a)
Garden Ideas: Level 1 Garden Sages Celebrating Gardening: 2015
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RoseBlush1
Jan 27, 2018 8:11 PM CST
Frank,

As I said in my post, there are several sources that say Bt does not work to manage rose slugs.

Here are a couple of links:

http://www.missouribotanicalga...

Bacillus thuringiensis (Bt), a commonly used biological insecticide that offers control of many caterpillars, is NOT effective against sawfly larvae.

http://www.mortonarb.org/files...

Although this insect looks like a caterpillar, it is not, so Bacillus thuringiensis var. kurstaki (Btk) will NOT control this pest.

A further note ... On this site we are allowed to disagree with each other, but we do so in a civil manner. Your post to Zuzu suggesting that she should have someone else take over is inappropriate. It is a personal comment and not on topic.
I'd rather weed than dust ... the weeds stay gone longer.
[Last edited by RoseBlush1 - Jan 27, 2018 8:30 PM (+)]
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Name: Lilli
Copenhagen, Denmark, EU
Irises Roses Bulbs Hellebores Foliage Fan Cottage Gardener
Plant Lover: Loves 'em all! Seed Starter Winter Sowing Bee Lover Dog Lover Region: Europe
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IrisLilli
Jan 28, 2018 5:57 AM CST
Frank, I agree with Lyn. No reason to get personal, just quote your sources and let people make up their own minds.
You don't know if it will grow until you try!
Name: Larry
Enterprise, Al. 36330 (Zone 8b)
Composter Garden Photography Million Pollinator Garden Challenge Garden Ideas: Master Level Plant Identifier Celebrating Gardening: 2015
Region: Alabama
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Seedfork
Jan 28, 2018 8:57 AM CST
Frank I have enjoyed your posts since you recently became a member, but I have so much respect for Zuzu and the knowledge she has shared I have to say your post was not fair to her.
Obviously you just misread the statement about Zuzu not buying roses for 30 years.
I think she was only doing due diligence in questioning a photo submitted to the contest when it appeared in other places (a compliment to you), I think to ignore such a situation, which I feel sure was not a pleasant thing for her to have to do, would not be optimal for a moderator.
I hope you can understand that, and if any of your photos are posted here by anyone else, I feel sure you would want that questioned?
Now I don't know the explanation as to why you have found something works that others say does not. I do find contradictions in gardening all the time, (high nitrogen will cause daylilies to have all leaves and no blooms for example).
I don't think Zuzu could be replaced by anyone, just go back and look at all the work she had done and the contributions she has made, staggering amounts of work.
Name: Frank Mosher
Nova Scotia, Canada (Zone 6a)
Lover of wildlife (Raccoon badge) Birds Roses Clematis Lilies Peonies
Region: Canadian Photo Contest Winner: 2017 Million Pollinator Garden Challenge
Image
fwmosher
Feb 6, 2018 3:16 PM CST
Firstly: A SINCERE APOLOGY to Zuzu for saying: "Hey, let someone else take over. I carefully read all my posts, I did say it, and I am sorry. Thanks to RoseBlush1 and Seedfork et al, for calling me on it!!! Not normally me.

I do have some concerns about the postings to my original post re: BTK and I respectfully want to address same.
Anyone can use "Dr. Google" to gain info on any topic they wish, and then use same to portend that they are offering the definitive answer to the question at hand. I often use Google. However, I have a considerable background in evaluating new pharmaceuticals/drugs via scientific double-blind crossover studies. My evaluation of BTK is not based on same. Rather, it is analgeous to having a "placebo" group, no BTK, and a "control" group on BTK, where the entire "placebo" group expires, and the entire "control" group survives. That simple! I can visually see the "driedup" carcases on the underside of the rose leaves.
Now, addressing the "slug vs catepillar" issue. First, here is a quote, talking about chewed-up rose leaves:


" I called an expert—Jeff Collard of Eberly & Collard Public Relations in Atlanta, the publicist for David Austin Roses, which supplied my beautiful bushes. "Are they the newer leaves?" he asked. Sure enough. It was the tiniest, most tender little leaflets that were suffering the worst predation. "To pests, the new leaves are like spring greens or young arugula to us—fresher, more tender, less bitter," he says. "They'll take the older growth, too. But the younger leaves are soft and easy to chew, yet full of nutrients."

But still the question remained: what pest was treating my rose bushes as the tender salad greens du jour? "How about sawflies?" he suggested. These pesky critters look a lot like bees, except that they don't do anything useful like pollinate crops. Instead, in the larval phase, "their caterpillars" (my quotation marks) dine on your plants.

I'd definitely seen a handful of sawflies in the garden, but no sawfly caterpillars. Nonetheless, I went outside for a closer inspection—and there they were!"

My words: There are at least three types of sawfly slugs: (1) Coiled like a snake, (2) Like a common caterpillar and (3) In the leaf-roller form - when you unpry the leaf, there are these small green caterpillars/slugs.You can call same whatever you want, and agreed technically, they are not supposed to be a caterpillar, but when they crawl over rose and pear leaves, devouring everything in front of them, including the sprayed BTK, they are gone within three days. Perhaps it is too warm in California to have rose slugs? " I personally have never used it". Consider yourself very fortunate Zuzu. "Fuzzy kittens?" If one has never used it, and heard the results from a serious rose grower who has, I would think twice about an outright "Google" contradiction. I read the Missouri study, and found it was lacking and without peer review. My only interest is in trying to help new Ht. Rose growers overcome some of the trials they will be faced with, and your own experiences with roses, although considerable, should be qualified with your geographical location and the dry pest-free conditions, under which anyone would have a distinct advantage. I can assure you, that you would never be able to squish rose slugs/caterpillars off 2000 roses by hand, and please send me, and any other rose grower north of California some of those parasitic wasps.
Yes, I was insulted when both you and Robertduval14 queried me on the source of my winning Rose photo. Even suggesting that one of my photos was identical to one on a chinese "Rose Seed" website. It was, but they had copied my photo, not the reverse. I have pictures of that entry dating back to 2012. My pictures of my roses. Lets give a cheer to growing roses, not personalities. This is not about you and me, but rather about increasing the interest in, and providing helpful info to new rose fanciers! Cheers!!!!!
Name: Larry
Enterprise, Al. 36330 (Zone 8b)
Composter Garden Photography Million Pollinator Garden Challenge Garden Ideas: Master Level Plant Identifier Celebrating Gardening: 2015
Region: Alabama
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Seedfork
Feb 6, 2018 5:53 PM CST
@fwmosher
Very pleased to read this last post, addressing the issues is definitely the way to go. I hope you don't still feel insulted, I don't think anyone doubts those are actually your photos now!
Name: Lyn
Weaverville, California (Zone 8a)
Garden Ideas: Level 1 Garden Sages Celebrating Gardening: 2015
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RoseBlush1
Feb 6, 2018 10:33 PM CST
Frank ...

Thank you for taking a step back. We all need to do that sometimes.

This last post is the kind I like to see on any forum because it generates discussion. We can compare notes. None of us knows it all and we all learn from each other.

I, too, have been checking with people who know more than I do, but cannot get into a discussion tonight. I just got back from a trip down the mountain for shopping and still have to put things away.

This is going to be a crazy week for me, but I'll get back to this thread when I can.

Your post today has now opened up the topic for any one else who may have information, experience or questions about BT or sawfly control.
I'd rather weed than dust ... the weeds stay gone longer.

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