One dry day is enough. You normally have to spray products every 14 days or so depending on the product directions during the growing season. Is by ”creeping black finger of death” you mean blackspot no organic method has worked for me.

Please define, "creeping black finger of death," so we know which exact fungus you are talking about? Black spot is the presumed guilty party, but just to make sure....

Moses.

Actually, I'm not sure what it is. What's been happening is as follows: I planted out potted/bare root roses at the proper time for my climate-autumn. Plants grow,look fine-even seem to make it through the hideous weather of July in good condition. Then, BAM-in August canes start going black; starting at the base,a little black area,and eventually spreads upward, killing the cane. What started out as a healthy young rose is reduced to a pathetic single little cane.

The first year this occured, I assumed it was sunburn, the excessive heat, and the fact that I just can't water enough now that the summers have become so extreme. I tried removing the blackened area,and using an anti-fungal sealant, but the results were mediocre at best.

The following year I put up shade cloth in June,and installed drip to help with the watering. Things were a little better,but not great,and these plants are showing no signs of bouncing back.

I've read of others on this forum who have had similar issues.

The closest thing that I've managed to find on Internet that seems similar is this portion of an article from Ludwig's roses in New Zealand https://www.ludwigsroses.co.za/rose-growing-tips/rose-care/what-could-be-wrong-with-my-roses/ Here's the somewhat pertinent section:

"Though sunburn is not a disease in itself, it causes a secondary disease known as stem canker or coniothirium. This is caused by bacteria and no remedial sprays are available. It causes ‘die-back’ or rather ‘die–up’ of part of the rose bush, or even the entire bush. A secondary fungus and bacteria settle in dead tissue almost immediately, and soon attack the surrounding healthy tissue as well. Black to purplish blotches become visible on the stem. The xylem capillaries through which sap is transported are blocked or severed at this point and, once the dead tissue has encircled the stem, the above section shrivels and dies.

Sunburn occurs on the lower parts of the stems, usually on the curvature just above soil level. It can happen in early August, when the stems are still bare after pruning, and the sun rapidly warms frozen tissue after a frosty night. In regions that expect late frost, it is advisable to spray after pruning with a solution of 1 part lime sulphur to 5 parts water, or use limewash. The residual whiteness reflects sunlight.

Sunburn occurs more often and with more devastating results in the heat of summer, when the lower parts of the plant are not shaded by a canopy of leaves and when water in the surrounding soil is allowed to heat up because of insufficient mulch or cover. Sudden leaf drop (caused by black spot, spider mites, hail etc.) can slow down the sap flow so much that normal cooling processes – liquid moving through the capillaries – does not take place.

If blotches are apparent but have not spread too much upwards (they never move downwards), it is still possible to retain the affected stems by sealing them with Steriseal. The stems will put on new growth and, with the sap flow restored, callus growth around the edges of the infected areas will prevent the disease from spreading. Such branches can be removed at a later stage during routine pruning, by which stage new basal stems will have taken over."

This doesn't exactly desribe what I'm seeing, but it seems similar. However, looking up "coniothirium" on Internet produced confusing results .I still have to do more research on this though. From my superficial investigation, it seemed like this "coniothirium" might be a fungus that combats sclerotinia another fungus that cropped up on Internet,but the supposed cure for that is this product called "T4 Biocontrol", which costs around 250 dollars for a package. That's not happening, for sure, since I don't really know the exact thing that's causing this.

Where are you?

bart Bart I am sorry your roses are being affected by this awful thing. The blackness you mention is not something I have experienced here and definitely does not sound like black spot. I have only gotten black canes that expand and kill the plant after winter damage so definitely different but maybe a similar effect with extreme temperatures? I how high are your temperatures getting there? We never get over 105 F or 40c where I am, but in Arizona and other hot areas they probably get similar temperatures to you in the summer I hope someone knows something about it.

I am not sure that spraying fungicides will help this situation, but it probably won’t hurt to try. I would just choose a real anti fungal spray and follow the recommended doses and see what happens. I would not waste any money on organic methods unless they have been proven to work.

@kitasei2 bart bart is in Italy

Thanks, daniela. I'm planning on using fungicides that I bought locally. One is lecithin-based; according to the man at the "agricultural store" (here,that store is called an " agraria"), this is the new frontier in disease control. I'm going to also use a systemic fungicde bought on Amazon (reasonably priced!),and I've got a third product; I plan to alternate these.

I suspect it does have something to do with the extreme summer temperatures,followed by a sudden drop to more normal heat, but which an organism experiences as "cold" because it's used to the extreme heat. Fact is, I myself tend to get sick when the temperatures drop like that in August. Italy's climate is not a very healthy one, IMO. Even back before global warming really hit us so hard, there was always a huge difference between the temperature when the sun was out during the day, and that of the evening.One of the many reasons why I adored Ireland was that there was only a very slight shift in temperature from day to night.

Still, I want to try the fungicides as a sort of last-ditch attempt at growing floribundas. Naturally I intend to use the shade cloth again, and will do my best to water...

I too get this problem sometimes . A healthy mature rose will develop a black cane from the top .Even if I remove it from the bottom , other canes will start getting black and the rose would die eventually in a few months .

I spray regularly but have chilli thrips & spider mites also high heat & humidity most of the year .

I did ask about it in my local Rose Society and was advised to apply a copper based fungicide like Cupro . I did and that made matters worse as I didn't know that copper shouldn't be applied during hot weather .

Moses, a shade collar? Brilliant idea! I’m about to Google “light colored 2 gal. Buckets.”

Moses, this problem has only occured to very young plants,mostly it's happened with floribundas . For example, the potted Grandmother's Hat that I put out is doing fine. None of my mature roses have it,but of these the only floribunda-like ones that pop into my mind are Country Girl and Eyes for You. As for the placement, I have recently been concentrating on planting in a couple of areas,so I have no way of knowing if it's something specific about these areas or not. However, the Gma's Hat that I mentioned is in one of these areas.

It is almost impossible to identify all the variables involved. It has mostly happened to floribundas, but also to "Climbing?" Violette Parfumee (it's supposedly the climber, but has shown no real vigour that confirms that it really IS the climbing version),for example. I've also been concentrating my attention recently on modern varieties,so it is decidedly possible that perhaps moderns are not adapted to my current conditions. Another thing: I suspect that these past few years have been too dry. Even though it did rain, it was in a different way from the "usual" pattern of rain in my climate. I think it did not rain as much as it "should" have during fall/winter, but did rain in, like May? or something? don't remember exactly. This fall/winter have, thank Heaven, been very rainy-more like it used to be in the past. Again, I reitirate: this only has been happening to new implants ; they seem to be boogie-ing along just fine, until the end of summer, when this happens, and they don't revive (ie, die, or remain as one pathetic little stick). They just don't establish.

I like the shade collar idea, too, but am concerned that a plastic bucket would limit air circulation too much. As I have said, the problem ONLY effects roses that are trying to get established,that have no woody canes, only young green ones, and that the "black finger" begins near the base of young, green canes. Perhaps the idea of cutting up a bot or backet so only one side of the little plant is sheltered could work, however.

I hope to try spraying this year, but if that changes nothing, then I think I'm done with floribundas.

Re shade collars. The same effect can be achieved by thick mulching. Just my opinion, but I would not want a garden of upturned plastic buckets.

That's if one subscribed to the 'Clematis like cool roots' theory. Many don't and consider it a widespread garden myth.