Hi this is my first year growing roses and I have 2. One is a knockout yellow rose bush and it is doing great and is absolutely beautiful. My other rose bush is a Chicago hope hybrid tea rose and just keeps getting worse and worse. I believe it has blackspot, leaves get dark spots that get bigger until they cover whole leaf and gets on the leaves all around it if I don't clip them off as soon as I start seeing the spots. I am using a sulfur based spray on both plants every 7 days and feed it MG for roses (1gallon each plant) every 7 days. It starts to look better then bad again, it's done this all spring/summer. I've had a few blooms which are beautiful but it keeps getting to be less blooms and a lot smaller than when I first purchased it. It'll be winter soon and I'm wondering if there's a way to fix it that I'm not doing? Would it be better to leave the sickly rose in the ground and mulch or dig it up/pot it and bring inside for the winter? I'd appreciate any help I'd really like it to make it but there's only couple stems left alive on it and they are pretty short.
Pests and diseases: Prevention is the best way to avoid pest and disease problems. Start with disease-resistant varieties, keep plants in healthy condition (well fertilized and well watered), maintain good air circulation, keep foliage dry, and remove any diseased foliage or spent flowers. For Japanese beetle grubs, use beneficial nematodes or Milky Spore (Bacillus popilliae). Rose Rx is effective against scale, spidermites and aphids. For more information, see the Pest and Disease Finder.
There will be disappointments along the way, when many rose seeds fail to germinate, or perhaps they do germinate, only to die several weeks later from damp-off disease. Sometimes a rose seedling will turn out to be as ugly as sin, or very sickly, and you will reluctantly have to throw it away. Other times they will be just ho-hum, or look too much like its parent, and therefore have no value. But, just when you don't expect it, you might discover that one of your rose seedlings turns out to be very special.