Description and Symptoms
Crazy top (Sclerophthora macrospora) affected plants are distorted and/or stunted. The leaves below the tassel may proliferate, resulting in a very bushy appearance of the top of the plant, which lends this disease its name. Internodes may be short or long; there may be a proliferation of ear shoots, leaves that are narrow and strap-like, excessive tillering, or a complete lack of ear and tassel formation. Crazy top is more common in fields that are flooded early in growing season. Proper soil drainage will reduce the risk of infection.
The best time to scout is V4 through R6. A good scouting tip is that saturated soils in springtime can lead to infection.
Crazy top is not a severe disease but it can cause significant losses in low-lying areas of fields that are prone to flooding, since infected plants are often barren. This disease is best managed by improving field drainage or by avoiding low, wet areas in fields. Rotation may be helpful if care is taken to keep rotational fields free of grassy weeds.
Therefore, there's not much that can be done to manage this disease in season. Pulling up and discarding infected plants can reduce buildup of inoculum in the field, and thus reduce the risk of disease in subsequent years.
Photo by Adam Sisson