The Q&A Archives: Disease on Knock-Out Roses

Question: June 5, 2006. Zone 4. I planted two Blushing knock-out rose bushes last spring. I pruned them almost to the ground this spring. Last summer they did wonderful-no signs of disease or stress. Now this spring, starting in May the green leaves are almost completely eaten through with tiny holes (they almost look like

Answer: I'd leave the plant alone and just put up with the lacy foliage. You might try pulling a few of the leaves off to see if your shrub will replace them with healthy new ones. If so, you can pull the rest of them off; if not, you'll just have to put up with them for the time being. Fungicides protect against diseases such as black spot, rust and powdery mildew, but won't protect against insect attacks. I suspect that beetles or worms fed on the leaves. The pests were probably long gone before you even noticed the damage so spraying with insecticides will have no effect. I'm afraid you'll need to catch the pests in the act in order to control them.

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