Infections occur when leaves are wet with dew or rain. Serious outbreaks can occur during extended periods of humid, wet weather. Rotate away from forage legumes for at least two years. Some varieties may suffer less yield loss, but varieties with high levels of resistance are not available. Tan leaf spots with brown borders, giving an eyespot appearance.
Spots sometimes have a yellow margin.
Leaves and stems eventually blight and turn tan. Spots may be evident in all but the youngest leaves on growing shoots. Most severe in first or second cuttings. Favored by cool, wet weather during alfalfa regrowth. Disease pressure is often high following freezing of alfalfa stems or in fields where a cutting is left unharvested, because dead alfalfa leaves and stems are often colonized by the fungus.