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Black fungus on rose bush leaves, help!

Posted by txrose SE Texas (My Page) on
Sun, Jun 10, 07 at 14:23

For some reason I am getting a black fungus on the leaves of my rose bushs, it starts out with black spots on the green leaves then the leaves start turning yellow then most fall off, I have 3 bushes in the front of my house which faces south and I have 4 more on the side of my house which faces west, they are ALL getting this and my bushes all look bare and sickly. I pinch off the rest of the bad leaves and the ones that have fallen off and bag them up, but it just seems to keep spreading. I haven't noticed any type of bugs either, I looked the best I could.
I only water in the early mornings. Is there any remedy for this? I really hate to have to toss them all.
I need help!

Follow-Up Postings:

RE: Black fungus on rose bush leaves, help!

You have the VERY common rose disease called Black Spot. There are numerous remedies for a search and find one that best suits you.

RE: Black fungus on rose bush leaves, help!

I read an article by a Smith County Master Gardener, and his suggestion is:

Control black spot on roses with triforine (Funginex) or other labeled product.

RE: Black fungus on rose bush leaves, help!

You can spray with baking soda & water for an easy, inexpensive fix.

RE: Black fungus on rose bush leaves, help!

I think it does a huge disservice to new gardeners (not to mention to the rest of the environment) when a chemical solution to a problem, and a fairly toxic one at that, is one of the first proposed.

Much of the impact of rose black spot can be eleviated if good cultural practices are followed. Good cultural practices equate to good gardening practices, so new gardeners can learn as they go what conditions plants need for healthy growth and how best to care for them to maintain that health. As rhizo suggests, a Google search will turn up countless sites outlining what these may be as well as many less disruptive methods of control. In addition to the baking soda and water method mentioned above (aka the Cornell formula), milk and biocontrols like Neem oil will also help if used attentively and at the appropriate time.

It is always most desireable to attempt the least environmentally disruptive controls first and leave the chemicals as a last resort.

RE: Black fungus on rose bush leaves, help!

Gardengal48 has got it right! Start with good cultivation and remember that roses want lots of air flow, so give them space. Then, if the need arises begin using the least toxic curative; and use poisons only as a last desperate resort. Never forget that any poison you use will get onto the ground; any that is on the ground will end up in our water system. Think about whether or not you want to drink it, before you spray it.

In my garden -and I will be honest and say the roses do *not* have enough air space around each plant- I mulch with shredded leaves while the roses are dormant. Alliums and chives are planted so they surround each rose. When blackspot arrives -- and this is hot'n'humid DC, so it does come every year -- I drench each plant with a solution of 1/4 cup skim milk added to 1 gal water, once or twice a week. It doesn't make the spots disappear (nothing does that, so prune spotty leaves) but it does stop the spread. If you start when the first spot appears, you likely will not have any more infestation unless you skip a couple weeks. BTW, I used a baking soda solution until trying the milk. Baking soda is effective but seems to require more frequent spraying plus leaving a whitish film on the leaves. The milk seems to disappear although you may notice the rose putting out many more new shoots -- roses apparently consider milky water nourishing.

RE: Black fungus on rose bush leaves, help!

  • Posted by lindac Iowa Z 5/4 (My Page) on
    Fri, Jun 15, 07 at 13:23

Also, shredded wood mulch to keep the soil from splattering on the leaves when it rains is said to help keep black spot at bay.
Linda C

RE: Black fungus on rose bush leaves, help!

Your problem right now is possibly due to lack of deep watering and a hungry soil.

You're absolutely right to pick up the dead leaves because that does help to cut back on reinfection.

For the soil, if you can add a good thick mulch of well-rotted garden compost (so you can't tell what went into it) and some ancient, no-smell-now steer or horse manure which is all crumbly, mixed in. About one bucket of manure to four buckets of compost.

When autumn comes put about a two gallon swish of wood ashes around each plant. That's ash from untreated wood only. The ashes add potash and that helps strengthen the plants against disease and frost damage, too.

You'll probably find that you'll get black spot again toward the end of the summer when all manner of fungi start showing. Just use one of the recipes already supplied.

And, for next year - start with a well-fed soil. You can repeat the compost application in spring once growth has begun - but keep it back from the stems. The compost you put on now - and in the autumn - will be what the roses will be calling on for goodness to grow with. The spring application won't really become available until further on in the season.

If your plants are getting too dry, you may also have a scale infestation along the stems. You can reduce this with winter oil or even soapy water and a dishwashing brush scrubbed over the infested stems. Prickly work - but worth it.

RE: Black fungus on rose bush leaves, help!

I have black spot on my "black spot resistant" knockout roses. I've read that I need to clean up all the dead leaves and destroy them. Honestly, how does one get in there and get the leaves without shredding your hands and arms?
I've sprayed them once with Daconil but it keeps raining! I live 40 miles west of St. Louis. I have these roses on 3 sides of the house. Only the roses in front of the house have black spot. I want to keep the others from getting infected. HELP!

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