Knockout Rose Bushes

Knock Out Roses

Anonymous added on August 17, 2017 | Answered

This is the first year after many years-- that my roses have three of the five diseases.. rust, mildew.. and black spot. What am I doing wrong? I feed the roses a systemic fertilizer in spring and then fertilize with Miracle Grow spray every three weeks. There are few leaves at the base of the plants. They are situated where there is air going through. Because of hot weather and drought in our area I water at least twice a week at the stem, never on the leaves. With all thats going on? Should I cut the plants back now? Thanksyou.

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Certified GKH Gardening Expert
Answered on August 18, 2017

It does not sound like you are doing anything wrong. First you need to spray your roses with a good fungicide. Green Cure is an earth friendly fungicide that when applied at the Cure Rate listed on the label will clean up the fungal diseases mentioned. Black spot can be a very tough customer to deal with. It will sometimes take a stronger fungicide such as Mancozeb to get it killed. The black spots never go away from the foliage it attacked, but if killed, the new foliage should be free from the black spots. When the temps get real hot, a rosebush will drop foliage in an effort to keep itself cooler. Also there are times that the upper new dense foliage shades the lower foliage. The bush is not benefiting as much from that lower foliage so it naturally lets it turn yellow and fall off. Your well established roses are just doing their natural thing for a hot and dry year. Keep them watered and give them a good organic or organic based rose food, spray them with the fungicide and things will be fine. Oh and don't forget to give each of them a cup of Kelp Meal, they love that!

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