I am not sure what type of fungi you are trying to kill or even if the plant has a fungus and not a mealy bug infection or mildew. In general cut off infected plant parts, increase air circulation and do not wet foliage by overhead watering if you can help it. There are many different kinds of fungicides and also horticultural oils that will help if you do have a fungus. Perhaps you could take a sample of the plant damage to a Master Gardener clinic for proper diagnosis before you invest in a fungicide spray. Good luck and keep growing, Marianne Binetti