If your rose plant has curled leaves with yellow spots and/or a sticky substance, chances are it is infested with aphids, very small, light green or black insects. Although aphids won't kill the rose plant, they suck the sap out of the more succulent parts of the plant, decreasing its aesthetics. The substance that they leave behind is a breeding ground for various fungi that can be detrimental to the plant. Insecticidal soaps, because they block the aphid's breathing holes, work well in aphid management.
Pour the vegetable oil, dishwashing liquid and water into the spray bottle. Shake to combine.
Spray all infested areas of the rose plant, including the undersides of leaves. The sprayed areas must be dripping with the mixture.
Allow the mixture to remain on the rose plant for three hours, and then wash it off the plant with a garden hose. Make sure to remove all the soap from the plant, as it can burn sensitive foliage.
Repeat the procedure every three days until the aphids are gone.