My knockout roses wee beautiful last year but have struggled this year. They budded in the spring but the buds never fully bloomed. They turned brown and died. A friend told me to try cutting the bushes way back to see if the needed to rejuvenate. When I did that I was able to see the stems much better. After doing a little research I am now worried that they may have rose rosette. What do you think?
I'm no expert but after looking up Rose Rosette and comparing them with your plant, it really doesn't look like it has the disease. It's just my observation and I might be wrong.
I don't see any evidence of RRD in your pictures. This spring in the SE US was really hard on some plants due to unusually warm weather followed by a hard freeze (much of the peach crop in SC and GA was destroyed). I don't have 'Knockout' roses but I did see significant damage to some of my roses (new growth and buds frozen and turned brown). So probably what you're seeing is just the result of extreme weather. 'Knockout' roses are tough and yours should recover. In general, with roses in our area, major pruning should be done around mid-March (earlier may encourage new growth that could be killed by a freeze). Light pruning is OK during summer through August (not later than that as new growth may not have time to harden off before winter).
If you can get a soil test I'd recommend checking the pH and nutrient levels of your soil. Be sure not to over-feed your plants and kill them with kindness. With fertilizer, more is not always better.
Hoping someone can tell me if this is a Tithonia Diversifolia. It grew under a birdfeeder. Could it have grown from the birdseed? Im in Cincinnati in Zone6a.
