Wildflowers can be affected by numerous diseases regardless of their aptness in natural habitats. Fungal pathogens, specifically mildew, gray mold, stem rot, and aster yellow are the most common. Mildew causes leaves to shrivel up and die, which in turn can cause the flower not to bud (Mildew). Gray mold causes seedlings to die and spreads spores easily throughout the field to more, otherwise healthy, plants (Gray Mold). Stem rot causes lesions to grow on the stem of plants and ultimately weakens and kills the plant (Stem Rot). Aster yellow is a viral disease spread by insects called leafhoppers that suck the sap out and infect the salivary glands of the plant (Aster Yellows).
The best way to prevent diseases in wildflowers is to pant selections that are less susceptible to disease. Also, avoiding the use of overhead sprinkler irrigation can help. Overhead watering causes the wildflowers to remain damp for long periods of time, something that wildflowers are not well adapted for in nature. Prolonged dampness is one of the principal conditions that many fungi require to grow. For more information on preferable irrigation methods, please see Methods for Irrigating Forbs. Fungicides are also an option to aid in disease control. The best time to apply fungicides is as soon as diseases have been identified. For the home gardener, applying compost is another, altogether natural option. Compost (organic matter) is a great way to keep the soil and plants healthy, thus reducing the risk of diseases.