Garlic Spray works in controlling aphids, leafhoppers, whiteflies, and some fungi, and nematodes as well.
-Soak 6 tablespoons finely minced garlic in 2 teaspoons mineral oil for a minimum of 24 hours.
-Add 1 pint of water and 1.5 teaspoons of liquid dish soap.
-Stir and strain into a glass container for storage.
-Combine 1-2 tablespoons of this concentrate with 2 cups of water to make the spray.
-Test the spray on a couple of leaves and check after two days for any damage from the soap/garlic mixture. If there is no damage, then you can spray your plant thoroughly, ensuring good coverage of the foliage.
I know that planting garlic amid your plants also wards away any nasties as well, so I don't see why the spray would not work.