Diacon is an insecticide, not a fungicide.

Did you mean Daconil? It is an effective blackspot fungicide if used every 7-10 days.

A more effective fungicide is Bayer Advanced Disease Control for Roses, Flowers, and Shrubs. (Must be that exact name, containing only tebuconazole. Not the other Bayer products. DON'T LISTEN TO THE CLERK.) Try Lowe's and Ace Hardware--if not, you can get it online. It works very well at only 14-day intervals.

With a small number of roses, you may want to try an antitranspirant such as wilt-Pruf.

Here is a link that might be useful: link for above

Yes, sorry, I meant daconil, I'll try Lowes tomorrow for the Bayer. Do you think it will be okay if I don't strip the rose of the leaves that are effected? I really, really don't want to do this! They were doing so well!

Henry, Thank you, I read the link. I'm thinking this would have been a great product to have known about a month ago and I will definitly want to try it next year. My question is if I use it now and my plants are already diseased with black spot would it hurt the plant by coating the fungi that is on the plant? Should I wait until the plant has no sign of black spot?

If you are spraying regularly you can leave any leaves that are not yellowing on. Once they yellow they are no longer functioning and will die and fall off anyway so removing them does no harm. But green leaves with spots are still capable of feeding the rose until they turn yellow and your roses need them so leave them on. Black spot fungus spores are everywhere so picking all the leaves off and picking them up off the ground really doesn't have much effect on preventing black spot from happening. If the rose is susceptible and the weather conditions are right it's gonna happen.

Thank you Seil, I will continue to spray weekly and hope for the best!

When I sprayed Wilt-Pruf on leaves with blackspot, the blackspot did not progress any further for the rest of the season.

Hi mzstitch: There's a research done by Purdue University on artillery fungus splashed up from decayed mulch by the rain... You see it when you google "artillery, or shotgun fungus". This explains why Cantigny rose park nearby, with over one thousand bushes, DOES NOT USE MULCH, just bare dirt.

Henry_kuska once posted an excelllent article on the suppression of plant pathogens by soil bacteria. There are also articles on the suppression of plant pathogens by horse manure. Horse manure has lime, a potent fungicide. Lime, or calcium carbonate, raises the pH of the soil. There is a research done by the joint venture of United Kingdom and Sweden that showed alkalinity discourages fungal growth.

I tested the above with the 14 bands I received this March: 3 bands planted in pots with MiracleGro potting soil (green bag) with pH of 6.5. Two came down with terrible blackspots, one with mildew. The other 10 bands are planted in Organic MiracleGro potting soil (brown bag), neutral at pH 7. ALL are healthy, including the minis Love Ya Dad and Blue Mist.

The last band is planted in my limestone soil, pH of 7.7. It's Paul Neyron, notorious for fungal diseases. He's 100% clean, even with prolonged rain. Since the hose almost whacked his head off, I want to move him. Recently I ran an experiment before moving Paul Neyron: I acidified the soil on purpose by putting slow-release sulfur, plus watering him with acidified water - he broke out in blackspot immediately.

Pine mulch is acidic and I had the worst blackspot infestation when I used that many years ago. If possible, use something alkaline that DRIES OUT FAST like horse manure on a bedding of wood chips. They sell limestones in nugget-size, it would serve as mulch - and blackspots can't germinate and splash up with rain. Blackspots germinate easily on decayed mulch that stay wet for many hours after the rain.

Blackspot is mainly transmitted from cane to leaf, and then leaf to leaf, by splashing water.

Correction: It's Penn State that did the research on "artillery fungus". Here's an excerpt from the below website: "Recently more and more home owners have been complaining of tiny black spots appearing on their vinyl siding, down spouts, windows, and even their vehicles.

The dark spots are 1-2mm in diameter and slightly raised to globular. The black spots are masses of mature spores expelled from fruiting bodies of the fungus Sphaerobolus stellatus Tode. The fungus usually originates in wood-chip mulch that is used around shrubs, flowers and other plants. Wet, rotting mulch breeds small mushrooms that shoot off spores generally in spring and fall when temperatures range between 50 and 68 degrees. This fungus is more commonly referred to as shotgun fungus or artillery fungus because of the way it's discharged which is estimated to generate 1/10,000 hp and can shoot spores up to 20 feet."

When I checked on how black spots are spread, a British website stated that the spores are carried by wind, and also by mist in the air. If the rose is planted in an alkaline environment, thus becoming more alkaline in its tissue, there's less chance of blackspot breaking out. This explains why I don't have any blackspots in the 10 Austins planted in my limestone soil at pH 7.7. Penn State site stated that "mushroom compost mixed with wood chips can suppress artillergy fungus". Horse manure works the same way.

Here is a link that might be useful: Shotgun or Artillergy fungus

I'm really beginning to love this site, and all of the people so kind enough to help out. Strawberryhill, I do have pine mulch down, and underneath a layer of black kow. So, since this is a small manageable area that I will tend to weekly do you approve of me just taking the mulch away and not putting anything down? I don't really want to use wood chips as to me they are just a termite inviter so close to the house. I could go with limestone if I had to, but I would rather not as it would add to my workload of the way I like to pull away mulch yearly to layer new cow manure and bonemeal. As long as I keep up with the watering, no mulch would be the way to go. What do you think? Henry Kuska, I couldn't find wilt-pruf locally so I ordered it, will be spraying with Bayer Advanced until it arrives, I think this finally may be the ticket.

My roses leafed out earlier than I thought this year and I didn't get a chance to spray them before they did. Two weekends in a row it was either raining or too windy to spray. So I had a blackspot breakout on the more susceptible roses. I was able to spray 2 weeks ago with the Bayer. When I do spray, I also try to spray the ground under the rose in case there are any leaves with spores there.

I just sprayed again today. I don't see anymore yellow leaves or blackspot. The Bayer product is amazing.

Early warm weather last month, plus a warmer than average winter, meant that many of my roses never completely lost their last year's leaves. These old leaves are a perfect host for blackspot, which has come early this year, too. I'm late to the party with my sprayer, so I imagine that I will be playing catch up throughout the spring ... spraying and hopefully getting the bs under relative control.

The key to bs treatment and prevention is maintaining a regular schedule of spraying (every other Monday, in my case) and sticking to it. I use Honor Guard, the generic equivalent of Banner Max, which has the same mode of action as the Bayer Advanced Disease Control.

Tomorrow is spray day!

You need a bit more knowledge about Black Spot. The 'thing' that spreads the disease is a spore, and that spore is about 10 microns in length. There is no way in this blackspotted earth that removing leaves will remove all the spores. Likewise a few will remain on the canes, somemore will be in the mulch and or soil.

When people talk about vacuuming their beds to pick up the rose leaves, unless they are collecting in hepafilter bags the spores will just pass through the bag (with the air). I would even doubt that hepafilters would get out everything.

Blackspot is simply out there even though we wish it weren't. What we can do is reduce disease pressure within our own gardens. Henry does that by trapping any spores with an antitranspirant and making the surfaces of leaves less friendly to spores.

Other efforts go directly after the fungi once they are in the rose.

The other thing- some rose growers tend to lump all kinds of fungi into "Black Spot". If the treatments designated for BS don't work, look to the other fungi as possible sources for your outbreak.

I think, if BS was a big problem here, I might (like Henry) take antitranspirants seriously. (Or, I might be too lazy.)

But Ann's other point is well-taken.
In this astonishingly-wet SoCal spring, I thought I might see BS. No -- probably too cool. But I AM seeing what I think is cercospora -- an unusual pest, to suit this unusual season.

In our area, this, too, shall pass.

Jeri

Here is what the American Rose Society says of Black Spot:

"Biology High humidity is one factor that helps the spores to germinate. The spores germinate in 9-18 days on a moist leaf at 70-80�F temperatures. The spores can be spread by splashing water and by the Rosarians themselves. The spores are wind-borne only in water drops. The spores can be spread on clothing, tools or even your hands, but the way it is spread most often is by infected leaves that have wintered over in the rose bed."

Here is what Purdue University says:
"The disease cycle typically begins on fallen
leaves or canes that were infected the previous
season. Rain or sprinkler irrigation splashes
fungal spores from infected leaves that were shed
the previous year to the plant�s lower leaves. The
spores must remain wet for several hours for
infection to occur. Symptoms can become visible
within 72 hours after infection during warm,
wet weather, and a secondary infection cycle can
develop within 10 days after the initial infection.
The fungus that causes this disease tolerates a
wide range of temperatures, and symptoms can
continue to develop all season long if moisture
is adequate. The fungus overwinters in infected
canes and fallen leaves."

You are not going to spread spores with a vacuum cleaner.
If you are worried, use as I do, a wet-dry vac. and vacuum them wet. The spores will go nowhere but into the vac. or its filter.
If you want Black Spot gone clean, clean, clean. I use Serenade to soak the ground around my roses to kill disease remaining.

Just a note----

If you think that leaving a planting bed unmulched means that you're reducing "splash", well....I can't see how that's logical.

Ever walked on unmulched dirt in the summer? You may as well try to garden in concrete. Most gardeners who decide that mulching and weeding are not for them also find out in the summer that gardening isn't really their forte either.

Also, roses prefer acidic conditions, not alkaline. Please don't go dumping something into your garden to turn the soil alkaline because we'll be helping you figure out how to fix a chlorisis problem later.

There is no evidence that mulch has anything to do with it, except that a fresh layer of mulch would bury fallen leaves and perhaps reduce the splashing of spores back upward. However, there are blackspot lesions on the canes that carry the disease over winter and re-infect the new leaves. This is probably a bigger factor than fallen leaves unless you prune nearly to the ground.

Florabunda:
If you mean me I remulch after I vacuum and or hand-pick the leaves off of the ground.
I soak over the new mulch.

I also pick every leaf with black-spt off, even if it means denuding the rose.
I have not lost one by denuding it yet, although I rarely let it get anywhere near that point.
Leaves grow back.

No, Rpr---I was referring to the advice of getting rid of all mulch in order to combat blackspot.

Well, I certainly don't make a religion out of picking BS spotted leaves off a plant, although I sometimes pick off a number of the yellow-spotted leaves--mainly cuz they look bad and detract from the overall aesthetic effect. If the leaves are green and spotted, I don't pay them much mind--unless they get absolutely covered with spots and therefore ugly. I just cannot get uptight about BS.

When I see it, I spray twice with Bayer Advanced Garden Disease Control for Rose, Flowers, and Shrubs--about a week or 10 days a part. That usually fixes the current problem and prevents a future problem from starting. If the weather has been very BS prone, I might check out a few of the more susceptible roses and see if they need an additional spray a couple weeks later. Usually they don't. That's usually all I do in the spring. Rarely do I need to spray in the hot summer. Then in the fall, I may have to repeat the spring program again--although often I don't get around to doing much of any spraying in the fall--maybe once.

In between the sprayings, I will strip off a spotted leaf here or there now and then, and maybe scoop up a pile of dead leaves under the rose if they have built up--or maybe I won't.

That's about it in my garden.

Kate

"Put down fresh mulch and have been spraying them weekly."

If these roses are being sprayed weekly with Daconil and they are still suffering from severe Blackspot, then it would seem that these are unsuitable roses for this specific location, and different choices might be more worthwhile. JMO, of course.