I have had the same problem. It is a disease and you want to remove those leaves from the rose and those that have fallen. I use homemade mixes for mine, if you are interested, drop me a line and I will forward them to you.

I'm not glad that you're having problems with Knockout, but I am happy to know I'm not the only one for whom Knockout is NOT better than any other floribunda yet developed.

Nell

Yes I would be interested and also what I am doing that's causing this?

The leaves on my knockouts are also turning yellow and falling off. Still blooming profusely, getting plenty of rain/water, and the whole bush looks pale and thinned out; not as full and green. Do they need fertilizer, cutting back or what?

I have been told by the man who fertilizes our lawn that the knockouts need sulfur???? He is going to look at them when he comes by in the next day or two. I don't know if this helps any, but he does have a degree in agronomy.....

Beth florida
I am still interested in your home made mixes for my knockout roses. Some here in southeast Georgia have lots of blooms and others have stopped blooming completely. Mine of course have no blooms. They have greened up some, but as soon as it warms up the leaves start turning yellow again. I think it is relative to the amount of sun they are getting or being planted in beds next to crepe myrtles.

I planted a row of Knockout Roses two years ago and they've been a huge disappointment. They're fine when small and pruned back but as they grow they become thin, wirey and just ugly. Any advice?