Question
My 4 year and 3 year old knockouts were very healthy here in southern New Jersey until this summer. In June all bloomed but since then no blooms, yellow leaves, dead wood and swollen receptacles are in evidence. I am heart-broken. I performed "surgery" and cut back to main canes on some stems to remove what I guess is fungus. Now I am worried if August is the wrong time to do this. I thought it would stop the spread of the disease. We have had many heat waves this summer and this is the first summer I did not deadhead, been traveling. Thank you for your helpful advice.

Answer
Knock Out roses seem to hate high heat and will re-act by their leaves turning yellow, getting fungal diseases plus not blooming. You are right in that it wasn't a widow to cu them back at this time of the year especially in high temperatures but it won't kill them so don't worry. This time of year with heat waves is not the time to worry about roses as the will go under stress and shut down and look terrible.  Many gardeners are trying to just keep the roses alive with all the terrible weather we have been experiencing. Wait until the temperatures return to a cooler state and you will see new growth plus flowers. There really isn't much you can do if the rose has got a fungal disease because you could kill them if you use a spray in this weather. Again wait until it cools off and then use a spray such as Orthos Rose Pride for Black Spot and then you will have more success at solving the problem.