my sister sent me these three pictures of her neighbor's Knockout Roses. she wanted my opinion on the problem but i would like to hear from people on this forum before i talk to her again.
the roses are in st.louis, missouri. they have had a lot of rain, a very mild winter by their standards, cool temps then really hot ones interspersed. my sister says there are no webs or evidence of spider mites or any other pest. i'm leaning towards some kind of fireblight but i really just don't know.
any comments are appreciated.