I have 4 knock out roses & the leaves 1/2 down are turning brown
The bottom of the plants are bare with just stems. All the leaves turned brown and yellow and fell off. Is this a fungus?
It couuld be a fungus but could also be the bush just going through a natural system of trying to keep itself cool in very hot weather. Not sure what your weather has been like but such actions can directly relate to climatic happenings where you live. Here are some articles that you should take a look at for some further good information: