

Water carefully: Fungal diseases spread when plants stay in moist conditions and when water droplets splash contaminated soil on plant leaves.Rake and discard fallen leaves in the fall.Remove infected plant debris: Fungi can overwinter in contaminated plant debris, so remove all fallen leaves from infected plants as soon as possible.Purchase resistant varieties: Invest in fungus-resistant plant varieties to reduce the chances for black spot diseases.Here are a few tips to prevent black spot outbreaks. Apply an all-purpose fungicide to the entire plant, following the label instructions carefully. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread. Reapply as directed on the product label.

Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Organic options won’t kill the fungus, but will prevent it from spreading. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. Solutions: In minor cases of brown spot, there isn’t any need to treat the disease.
