IPM Identification and Mangement Of Turfgrass Diseases

Author(s)

Spring Dead Spot

Pathogen: Ophiospharella spp.
Hosts: Bermudagrass and buffalograss

Symptoms and signs

Spring dead spot appears as circular or arc-shaped patches of dead turf in the early spring as bermudagrass breaks winter dormancy. The dead patches are slightly depressed and straw-colored, ranging in size from several inches to several feet in diameter (Figure 1). The patches normally are randomly distributed throughout the lawn or fairway (Figure 2).

Roots and stolons of infected plants are dark brown to black and are severely rotted (Figure 3). The root rot symptoms are best observed near the margin of the dead area. Roots infected with Ophiosphaerella spp. turn dark brown to black as a result of extensive growth of the darkly pigmented fungus in and on the roots (Figure 4).
During the summer, bermudagrass slowly recolonizes the bare areas, but broadleaf weeds and other weedy grasses can also invade and colonize the bare soil, resulting in a clumpy or patchy appearance to the turf (Figure 5). By late summer there may be little or no evidence of the disease. Dead patches reappear the following spring in the same locations. Over a number of years, the patches can become quite large, coalesce, and develop arc-like patterns in the turf. After seven to 10 years, disease severity may begin to decrease to the point where the disease no longer occurs.

Conditions

Spring dead spot may occur on bermudagrass lawns of all ages, although it typically appears three to four years after the turf has been established.

Spring dead spot fungi colonize roots, stolons and crowns of bermudagrass plants in late summer or fall. Although most fungal colonization occurs in the fall, foliar symptoms do not develop until late spring. During winter dormancy, infected bermudagrass roots or crowns are either killed directly by the fungus or predisposed to desiccation or cold-temperature injury. Root colonization by the pathogen decreases the cold hardiness of the bermudagrass.
The disease tends to be more severe on high-maintenance bermudagrass lawns and fairways. Excessive nitrogen fertilization during the summer months enhances symptom development the following spring.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.