In an old thread I read the following information. I 'm also am having a problem with leaf drop on our rose bushes. After looking at the possibilities I have concluded it's: #4 Then there are the diseases. The most troublesome ones for roses are black spots and mildew. Black spots are obvious - it declares itself with those black roundish spots on the leaves. The leaves then turn yellow and fall off. But black spots tend to be a progressive disease. Initially a few leaves will be affected. Then, through cycles of rain and wetness, the spores of the initial lesions spread to adjoining leaves. Mildew is seen as a powdery residual or coating on the leaves. The powdery type is worse in dry conditions. We have had an extreme amount of rain here in the last month, almost 10 inches, so the over watering would fit. So what to I do now? Thanks
some roses are very prone to black spot and others not. i have some that get it and it's very hard to get rid of. it's easy enough to treat and keep under control with sprays made specifically for roses. the stuff that i found that worked the best was taken off the market (guess it's too toxic or something). it was an ortho product. i forget what i got after that was taken off the market...i have to go find it, too, because i just noticed my roses have the spots now (we just had over a week of rain). get something specifically for black spot on roses. spray well and make sure you coat the leaves on both sides. repeat treatment as per package directions. i found that, if i get the new growth early enough, it doesn't develop the spots even if the stuff is already active on other parts of the plant. it's something that needs to be done all summer to keep the stuff at bay. remove affected leaves. if you allow the leaves to fall to the ground and leave them, that promotes re-infection. same with any mulch you have down...that should be removed in the fall (or the top layer of soil if you don't mulch) and new put in place to try to reduce reinfection.
joclyn has some great advice. This is my first year using Bayer 3-1 Rose Care (supposedly helps prevent black spot) but we'll see. So I am hoping this is a none issue. As for your problem I would say Ortho Rose Pride Rose & Shrub Disease Control (concentrate). They also have a aerosol. Both endorsed By The American Rose Society. Also look into - SERENADE.
the ortho stuff i had used was better than the safer stuff (which i had used the year before i tried the ortho stuff). i'm not too big on bayer products because almost everything they offer is multi-use or multi-purpose. i like to use one product to treat one item - not use something to treat multiple things especially when multiple issues aren't even there. i'm not sure what difference there is with the active ingredient - ortho and bayer use different things in their products. and either one may be effective - with laws changing all the time, they have to accomodate by changing formula's which is why the ortho stuff i'd used before was taken off the market. such a shame! it worked fantastically, too. harry, please follow up with feedback on the bayer stuff. i'm curious to see if it's effective or not. that serenade stuff looks interesting!! the biggest plus with it is that it's organic...i may just try that along with the other stuff i have on hand...i have roses out front as well as in the back yard, so i can do 'test' treatments with no interference/cross-over of other product...
Well it's finally stopped raining about a week ago , but I needed to get our chile plot tilled and start planting the annual cut flower plots with this window of dry weather. In the mean time the poor rose bush, which by the way has been in full bloom for over two weeks is practically void of leaves and the ones left all have black spots. I did a very painful thing to this poor blooming rose bush - I trimmed it down to where about 8 inches of stems are visible above the ground. The reason I did this was there is a tremendous amount of leaf and pedal debris in and around the base stems (The plant's base is about 13" across). I figured if I didn't clean all the leaf debris from between the stems it would just allow the black spot to continue to propagate. I did wait till the most of the blooms had fallen, there were no new buds. So I did major surgery. Now my question is: Do I transplant the bush else where? or do I remove an inch of soil around it's base, clean out the leave debris between the stems and then put new soil around the bush and leave where it has lived for 9 years? any other ideas would be welcome. ChileRancher
not the best time to do a major pruning. definitely don't move it at this point (it's stressed more than enough atm), or at any point really, it's just a fungal issue that is easily dealt with. as already suggested, you'll need to treat with a fungicide - as soon as new growth appears, spray it well. continue with follow-up treatments as per package directions. if you get the new growth as soon as it's decent shape, that should protect it...you'll need to hit additional new growth as it shows up. removing soil, again, not quite the right time to do that - late fall or very, very early spring would be more ideal. at this point, if you still want to, do a light removal - no more than an inch down (you don't want to mess with the roots at this point because the plant is not dormant).
