I apologize for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
I am not sure what is eating the rose leaves so I can't tell you the best way to control it. There is a leaf cutting bee that cuts round holes about 1/2" in diameter in the leaves. They don't do enough damage to warrant control. Fertilize the bush every 4 weeks and water the fertilizer in well. This will encourage good health and vigor to overcome the loss from insect feeding. The leaf problem where they turn yellow and have black spots is the disease black spot. Black spot of roses is caused by a fungus. It is a major problem on roses across the country. The best way to manage it is to plant resistant varieties. There are several fungicides registered for use on roses that will control black spot, but regular spraying is required to maintain control on susceptible varieties.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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