Gardener Veronica Fowler offers a new twist on an old recipe that uses baking soda and oil to fight powdery mildew. Veronica’s version uses Murphy’s Oil Soap in along with the baking soda to form a spray solution.
1 gallon warm water
3 tablespoons baking soda
1 tablespoon Murphy’s Oil Soap
Thoroughly mix the ingredients and treat mildew spots when they first appear. Treat every 7-10 days until drier weather stops new spots from forming. The solution can also be used preventively on plants that have a history of mildew by spraying one or two times in early spring before the disease appear.