Black Leaves on a Clover Family Plant

Ornamental

• Some clover, such as the dark dancer black four-leaf clover, has been hybridized to display black, burgundy or purple leaves. They are usually grown as potted plants and houseplants or as bedding plants and ground covers, and are not found growing in the wild. Their striking colors add interest to landscaping projects. Intentional black or dark coloring is much more uniform than that caused by disease.

Disease

• More often, black leaves on clover are the indication of disease. Spring black stem affects red clover and causes lesions on all parts of the plant, including the leaves. Northern anthracnose also causes an overall darkening of the plant in severe cases, and also affects red clover in cool, moist weather. Sooty blotch is more common on white and alsike clovers, and causes dark spots on leaves. Pseudopeziza leaf spot blackens the leaves of sweet clover and alfalfa.

Feeding Clover

• Black blotch disease is caused by a mold that causes black spots on the underside of the leaves of clover. When horses in particular feed on the infected clover they experience photo-sensitivity. This is a thickening of the light-colored skin, and is actually caused primarily by liver damage. Sunburning is also a concern. Even dark horses experience liver damage, but it is more difficult to detect as the sunburn is not as visible.

Prevention

• The only way to prevent black leaves on clover is to control the diseases that cause them. If cutting and drying clover for hay, be sure to allow adequate drying time to prevent molding after cutting. For sooty blotch, rotate with a non-legume every three years. Reduce pseudopeziza and spring black stem with early cutting and choose anthracnose-resistant varieties when planting.