Question
In the spring I planted a knockout rose bush.  It was fine for the first month, then the leaves began to curl slightly.  The bush is healthy looking and isn't dropping any leaves.  I can't see any insects.  It is still producing roses.  Any Ideas?

Answer
When a rose gets mildew on the leaves, the fungus draws out the liquid or sap in the leaves and this makes them curl when they start to dry out. Try using 1 tablespoon of baking soda in 2 quarts of water as a spray and this will kill and stop the fungus damaging the leaves. However if the curl is just on the tips of the leaves and they are brownish, then this it could be fertilizer burn. Then I would pull back on the fertilizer for this season.