rose slugs

Discussion in 'Rosa (roses)' started by grdnstff, Jun 17, 2006.

  1. grdnstff

    grdnstff Active Member 10 Years

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    gads .. these critters have voracious appetites! .. is there any preventative steps i can take to stay ahead of rose slugs? .. they don't seem to harm the plant, othan than to desecrate the leaves, but i'd just as soon get them before they get to the leaves .. i'm open to ideas .. thanks
     
  2. Carol Ja

    Carol Ja Active Member 10 Years

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    If your sure its slugs, then you can do one of several things, slug bait, encourage them to go somewhere else with a beer, or what I do, which is put copper collars around the vulnerable plants, so they get zapped trying to cross.
     
  3. Margaret

    Margaret Active Member 10 Years

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    Hair placed on the ground around the rose make life difficult for slugs and many other pests. I use black lab hair - fortunately Max sheds a lot!! No reason why other hair shouldn't work as well though.
    Margaret
    ps. Want some of our garter snakes which love small slugs?
     
  4. Laurie

    Laurie Active Member Maple Society 10 Years

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    Here in the Pacific Northwest we are so challenged with garden slugs that they are the first thing to come to mind. However, the pest in question here is something altogether different. From an article by Baldo Villegas at http://www.ars.org/About_Roses/pests_slugs.htm:
    Roseslugs are the immature stages of primitive wasps called sawflies. …
    There are several species of sawflies that have been reared from roses in North America. Of these three species appear to cause the most damage[.] … Rose slugs look like caterpillars but they are not, consequently some insecticides such as Bacillus thuringiensis will not kill them. If there are only a few rose bushes infested with the roseslugs, pull the leaves off and kill any larvae found on the upper or lower surfaces of the leaves. If the damage is widespread to many rose bushes, chemical control should be considered. Any contact or systemic insecticide labeled for use on roses will kill the roseslugs. The key thing is to spray thoroughly to make sure that the spray covers the upper and lower leaf surfaces. Also, spray the soil under the rose bushes as the larvae pupate in the soil prior to overwintering.
     
    Last edited: Jun 22, 2006
  5. grdnstff

    grdnstff Active Member 10 Years

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    i hadn't actually thought of them as slugs, even though they're called 'rose slugs' .. it alluded me, i suppose, because they are tiny green caterpillar-like creatures, and so i have spent many moments picking them off the leaves .. however, now, it makes sense to approach them as i might slug slugs .. there are garter snakes around, i guess i'll just have to encourage them ..

    so .. once the slugs have decimated the leaves, they transform to the sawfly and leave the plant .. is that right .. then, will the leaves left behind, be alright to put into the compost? .. i'll go read the article now ..

    thank you, all
     
  6. grdnstff

    grdnstff Active Member 10 Years

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    hi, laurie .. i went to read the article about rose slugs, but cannot get a page for that url .. thanks, anyway ..
     
  7. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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  8. Laurie

    Laurie Active Member Maple Society 10 Years

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    Actually the colon ended up as part of the URL, which it shouldn't have. Thank-you for pointing that out; I will edit it. We actually recommend that rose leaves not be composted at all because of the chances of harboring fungal diseases, whether we see them or not. The damage to the leaves from the sawflies really does not matter with respect to composting.
     
  9. grdnstff

    grdnstff Active Member 10 Years

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    hi, laurie .. just getting back .. i had another wondering about the sawfly .. do you know whether they continue to live with the rose, or once the rose slugs transform do the flies leave? .. and, would dormant oil help with rose slug prevention, do you think?

    thanks
     
  10. Laurie

    Laurie Active Member Maple Society 10 Years

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    This evening I have not found an article that recommends either dormant oil spray or insecticidal soap. I believe that the adult sawfly is around, because of the three, the bristly sawfly has five or six generations a season, but the larvae pupate in the soil over the winter. It may be that choice of control depends on the number of affected rose bushes you have and the size of the area involved. I finally learned, after several years of no roses, that my problem here is rose midge, which I understand to be more serious. From first glance at a couple of articles, it seems that rose midge and rose sawfly have the same cycle and chemical control: the larvae pupate in the soil over the winter, so a soil drench of imidacloprid is necessary to ensure control. I saw Baldo last week at the spring national rose convention here in Bellevue, WA. Spraying the bushes always involves killing good bugs as well. Drenching the soil probably does too. I mentioned that I would rather give my hybrid teas and floribundas to my mom rather than to work on a problem that cannot be fully brought under control, which is the case with rose midge. Unfortunately, rose midge will move with the roses to the next garden. I am advised to cut at least the top third of each bush off and bareroot them (they are grown in pots) to dispose of all of the soil, where the larvae are pupating. If the problem with sawflies is minor, apparently it is advised to start to scout for sawfly larvae in early May (apparently from mid-May to mid-June slugs can be washed from the leaves with a strong spray, but hand-picking works), and cultivate the soil this season to break up the cocoons. Definitely avoid spraying the rose flowers with any conventional insecticides, almost all of which are toxic to bees. For chemical control, apparently acephate, carbaryl, bifenthrin, and malathion sprays for the leaves, and/or a soil drench of imidacloprid is effective.
     
  11. grdnstff

    grdnstff Active Member 10 Years

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    wow .. five or six times .. i was thinking once i got the ones off that i saw over a period of time, that i'd be done picking .. no wonder the leaves look so eaten .. i may have only been getting one, maybe two rounds .. i don't mind, at all, the idea of digging them up, washing them off and starting over again .. i'll do that - in the fall, i think - and see what the difference may be next year .. also, i tend to stay away from the chemical controls and will likely continue picking .. thanks so much for all your information, laurie .. here's to sawfly-less roses next year ..
     
    Last edited: Jul 10, 2006
  12. grdnstff

    grdnstff Active Member 10 Years

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    hi, laurie .. i'm just wondering, re the sawfly larvae, do you know, other than replacing the soil, is there any other preventitive measure i could take .. it seems to me that i could do the soil replacement, but what's to keep the flies from coming back to that rose .. i guess the dormant oil might help with that .. hmmm .. so many wonderings ..
     
  13. Laurie

    Laurie Active Member Maple Society 10 Years

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    Very little more is mentioned in so many articles that it seems that this is not a difficult problem to tackle, and that they will not likely continue to haunt you to such a degree year after year after they are under control. A few articles mention the botanically derived neem and rotenone, but with little direction, so it seems that they are meant to be sprayed during the feeding stage.. I haven’t found any mention of removing the top layer of soil for sawflies, but since the larvae pupate over the winter like midge, I thought that the treatment for the later might apply to the former.
     
  14. grdnstff

    grdnstff Active Member 10 Years

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    hi, laurie .. still finding so much evidence of the little rose slugs .. this seems to be my year to find out about them .. i just wanted to thank you for spending time checking out articles about them .. i'm starting to do the same .. thanks, again, for all your ideas ..
     
  15. Laurie

    Laurie Active Member Maple Society 10 Years

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    Good news! I just found a couple of websites - U.C. Davis and U. Minnesota - where they mention insecticidal soap for rose sawfly. I didn't have time to read through them, but here are the keywords to use on a google search: Endelomyia aethiops, insecticidal soap. Right now I am working on diseases and pests of maples, including what I thought was surely sawfly larva yesterday. Frankly, it is no fun to see so much damage from sawfly and midge in the roses. So if you find a great link that is helpful, or if and when you successfully use a non-toxic method to rid the garden of these pests, let us know. If you decide to spray with insecticidal soap now, assuming you are dealing with the species that has six generations per season, start with a clean slate so that you can monitor further damage. You can remove the skeletonized leaves, just as you can remove the leaves with black spot; more leaves will come. Don't spray though unless you are still seeing the larval stage, and remember to spray as early in the day as possible.
     
  16. grdnstff

    grdnstff Active Member 10 Years

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    hi, laurie .. this is wonderfull news .. i'm about to leave here and head to google to find the websites you've suggested .. whatever i discover, i'll bring back .. i continue to take off the leaves and, yes, see new growth coming .. watching it so carefully for evidence of new r slugs .. thanks, again .. be back soon ..
     

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