Dan Egel, Vegetable Pathologist, SWPAC, Botany & Plant Pathology, Purdue University
When most of us think of asparagus, it is as spears that pop up from the soil in the spring. After asparagus harvests are complete, however, growers allow asparagus to grow up into ferns as seen in Figure 1. The health of asparagus ferns must be maintained all year long in order for vigorous, healthy spears to be harvested in the spring. The ferns in Figure 1, however, are yellow and have many lesions. Closer inspection reveals lesions of Cercospora blight on these asparagus ferns (Figure 2). Cercospora blight lesions are gray to tan and may have a red border. Any practice that minimizes crop residue will help to lower disease severity. This includes burning and mowing/chopping ferns in the late fall. Fungicides may also help to reduce disease severity.