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Bad year for blackspot?

15 years ago

I'm hoping some of your rose-whizzes can confirm or deny my BS experience this year / calm me down or otherwise help me out.

I've got 4 roses in the ground (well, used to be 5, Pat Austin never survived the winter from last year). 2 Abe Darby's and 1 Wise Portia have been in the ground for the past 3 years; Glamis Castle I put in last year in early summer.

Every year, my roses eventually get some blackspot - usually towards the end of the year - September and esp. October. Last year, one of my healthiest Abe Darby's started showing some BS surprisingly early in the year - late July/early August. But still, it was very healthy, very nice dark leaves, prolific etc. Wise Portia is planted close to this one and eventually, many weeks later got some. Likewise the others got some also.

This year, as is customary, shortly after the roses got their leaves, they fell victim to the horrible rose slugs which after last year I learnt not to tolerate and so sprayed some bug stuff - Bon Neem I think it was - and got rid of them but not after they'd put holes in many many leaves.

Shortly thereafter - as in late May! this time - my roses started showing blackspot. All of them except for one of the Abe Darby's who still just has a mild case. Glamis Castle and Wise Portia have both been hit especially hard with it. Based on things I've read, I've been removing the infected leaves and have actually stripped more leaves from GC and WP than they have left. The one Abe Darby who didn't get a bad case of BS actually has quite a few "bald spots" on its stems as it never really replaced the leaves I removed that had been badly bug-bitten earlier in May.

Could you possibly tell me if this is an especially bad year for BS or are my beautiful roses just on the decline?! Is there anything I can do for them? Don't really want to use chemical fertilizers if it is terribly toxic, if I can help it.

The roses are planted to the South side of the house to get sun about 6-7 hours of the day about 11:00am onwards. Prior to that they are in the shade of the house (and have been for the 3+ years they've been with me). I've given them two rounds now of Rose Tone fertilizer (since early May) + a new dose of composted manure earlier in the year. I haven't actually put in any mulch this year. Should I do so? It has rained quite regularly this year and on the weeks that it hasn't rained at least 3 days in the week, I've given them a deep watering once a week.

What am I doing wrong? Please help/ advise.

Comments (12)

  • 15 years ago

    The regular rain several times a week practically guarantees BS on susceptible varieties unless sprayed with a fungicide. You may want to look into disease resistant varieties that don't need to be sprayed.

  • 15 years ago

    Like Zack said, it's been a really damp year and black spot (and for me mildew too) has had a field day.

  • 15 years ago

    Gosh I'm so glad to hear that! Sorry to sound so heartless, but I am really glad it isn't just my roses! Yes, it has been quite a damp year all around.

    Zack, what you say sounds very rational. However, I must confess to being somewhat uninspired by the hardier options in Eastern Massachusetts. Each year I try to convince myself to like something that is naturally disease resistant here but can't find myself especially motivated by my options.
    I've lost an OGR (SdM) that I understood would be hardier to diseases but it wasn't hardy enough to withstand the winters - she was my hands down favorite rose but didn't return at all after the first winter. My DAs however at least come back every year. Well, except for a Pat Austin who never made it into the ground last year and didn't survive the winter even in the shed. I'm not too keen on the Knock Outs, not much of a Tea Rose fan ... I heart the OGRs but they don't care so much for me. I do love the English roses though and will try to find some more disease hardy varieties - would love suggestions for options that are good to Boston parts' pressures of summer heat/humidity and tough winter conditions.

    Thank you every so much Zack and seil.

  • 15 years ago

    Blackspot overwinters in the bark, so foliage coming off old canes will be infected quicker than the foliage of new shoots from nowhere. So in zone 6, cane-hardy shrub roses will have more early blackspot than hybrid teas that were pruned severely. That accounts for your observations.

    Some Austins that may be more blackspot resistant for you are The Generous Gardener, Tess, and Teasing Georgia. These are all big, extremely vigorous plants in my climate. Heritage is also somewhat above average. Abe Darby was highly susceptible for me.

    If you need smaller plants, The Mayflower and Sophy's Rose are resistant in some gardens, not in others, depending on what strains of BS you have.

  • 15 years ago

    Here's what I would recommend.

    Get more disease-resistant Austins. There are lots of them, but David Austin doesn't like to use the negative word "disease." Instead, he more positively rates his roses by how "healthy" they are. Any number of them are listed as "very healthy." That is what you want.

    I'd recommend Queen of Sweden (pink, very disease-resistant, about 4 ft tall) and Molineux (yellow/apricot/creamy blend, fairly good disease-resistance, although not the best possible, and about 3-4 ft tall). They are both somewhat vertical bushes, so if you'd like the rounder, fuller look, plant 3 of each in a tight triangle (about 18 inches apart). It will grow to appear to be one full bush.

    Then, you must get Bayer's Garden Disease Control for Roses, Flowers, and Shrubs from Lowes and some kind of a simple hand-pump (try Home Depot). This is a fungicide--the only cure for blackspot. Spray maybe once a month--just as a preventative precaution. That should be more than enough since those two Austins are at least somewhat disease-resistant. In fact, you might not even need to spray that much unless the weather is particularly rainy.

    Both the roses should be hardy in your region, so I wouldn't worry about them surviving the winter. However, if you buy grafted roses, make sure the graft is buried a couple inches below the soil line. It is that graft in particular that needs protection during cold winters.

    Water weekly if there has not been sufficient rain. Feed about every 6 weeks with PlantTone/RoseTone/HollyTone--they are good.

    That about does it. It is all fairly simple--if you start with disease-resistant roses.

    Here is a link that might be useful: Queen of Sweden at helpmefind.com

  • 15 years ago

    I hear ya. Almost all my roses get black spot and look terrible unless I spray. Which I used to do, but don't have time anymore. I've had 3 that are constantly healthy without any care. Knockout(s), New Dawn, and Dublin Bay.

    Dublin Bay is surprising since many complain about how it gets BS. Not only that, but it's growing on my fence just inside the gate door and whenever anyone opens the gate (which happens about 10 times a day), it gets wacked. Maybe the wacking knocks off the spores.

  • 15 years ago

    Oh wow! I just checked in as I customarily do and what a bonanza of information.

    Thank you so much for the info!

    Michael, your info about BS overwintering in the canes sets off a lightbulb over my head. I made the observation last year that my very very hale and hearty new shoots (I had 5 basal breaks last year between my 3 older roses) that were growing long thick and round (branches, that is) were so much more resistant to BS than the other older ones which were also spindlier older growths from the past.

    This year, much to my surprise, the leaves on these still nice new thick branches were showing no less BS than those on the old skinnier stems.
    That had surprised and dismayed me.
    But now I understand.

    I've had my eye on Teasing Georgia, & Generous Gardener for ages but they scared me just a touch, truth be told, by their size. Not the size exactly, but just how much I fancy sun they would want to support that size :-). I don't know that my suburban Boston garden is allowed that much sun! But they are compelling options and I will look into getting them.

    Dublinbay, QoS is a great recommendation. I've had my eye on her and her very manageable size made her very very tempting. But she looks so delicate that I just wasn't sure about her hardiness to disease etc. So I'm delighted to read you recommend her so well. Really happy about that.

    That said, Abe Darby and WP are such utterly gorgeous looking and smelling roses that it is hard to give up on them. Still, for a new garden spot, these are heartening recommendations.

    To your mind, do the organic fungicides work? The fungonils and copper sprays or others? Or is a chemical spray a given?

    kidhorn, I've been sufficiently annoyed by the sight of all the BS that even though my roses aren't by a gate, I might just whack them morning and evening and see if the whacking does the spores in.

    Thank you all ever so very much. This still newbie gardener very much appreciates it.

  • 15 years ago

    Those BS spores will always be there. You need to spray on a regular schedule to prevent BS from starting. If spraying is what you want to do.
    I myself have no faith in organic fungicides, I'll let it at that.
    I do not spray here, I try to plant only disease resistant roses and that's working good so far for me here at my location.

  • 15 years ago

    Ditto - organic solutions for BS are useless in my area.

    IMHO, there's nothing to fear from -azoles, the type of chemical used in the Bayer Disease Control (tebuconazole) and Banner Maxx (propiconazole). I shampoo my hair with similar stuff (Ketoconazole). It's also in pill form used to treat fingernail/toenail fungus.

  • 15 years ago

    Having terrible BS on the majority of my Austins and some very old (35yr old) tea roses, It rained pretty much everyday here in March and April.

    Not much I plan to do now, in the fall I will rake and replace all the mulch and try and curtail it a bit for next season,

  • 15 years ago

    My TG gets BS, bu doesn' defoliate as some roses do. I've never seen BS on Sophy's rose, but it does get some PM. I do spray, but here are times I'm lax (usually in the fall) and that's when I can tell who the BS problems are. Although, IME, any rose will get blackspot.

    I use the Bayer spray and usually spray every two weeks. Unless we have a hot dry spell, as we did back in May. I was able to skip a few sprayings back then.

  • 15 years ago

    Lol, kidhorn, I love it! I may just go out and whack my roses too!

    A note to all of you who are relying solely on the Bayer Disease Control, you may be setting yourselves up for an even bigger problem by not rotating it with some other product that has a different active ingredient. By only using one product all of the time you create resistant strains and that product will no longer be effective at all. There are other products with different ingredients availble. Try switching them in once in a while.