Sclerotinia fungal disease infects nearly 360 different plants, including such favorites as beans, cabbage, tomatoes, lettuce, sunflowers, petunias, zinnias, and poppies. It's not the kind of disease you want to encourage in the garden
New research, however, indicates that by feeding birds, we may unknowingly be doing just that. Steve Nameth, a researcher at Ohio State University in Columbus, started noticing sunflower seeds infected with sclerotinia fungus while feeding his birds. The fungal infected seeds are about the same size as healthy seeds, but are irregularly shaped and white inside if broken open. As any good researcher would, he became curious about how much sclerotinia infected seed is in a bag of sunflower seeds.
Nameth bought a random sample of 10 commercial bird seed mixes and found that half had sclerotinia present in the feed. Birds won't eat sunflower seeds infected with the fungus, so they drop to the ground under the feeders, sometimes right next to plants they can infect. The fungus can stay dormant for years waiting for the right weather conditions to infect nearby plants.
If you're noticing disease on stems and flowers of plants near your bird feeder, particularly if infected parts are covered with white fluffy growth, consider moving your feeder away from your gardens. It's also important to keep the area around the base of the plants clean of plant debris, and to pick up and destroy dropped seed. Don't use the dropped seed as mulch in the garden or in the compost unless your compost pile heats up to 160° F.