Leaf blight

Helminthosporium spp

Turfgrasses Affected: All warm-season turfgrasses can be affected, but the disease is usually most serious on bermudagrass. Different species of these fungal pathogens affect different species of turfgrass.

Occurrence: This disease is caused by a group of fungi that is active over a wide range of temperatures. At any given time of the year, at least one species within this fungal group can be isolated. Thus, diseases caused by these fungi can occur at any time of year. However, as a general rule, the leaf spot disease occurs during mild, wet periods during fall and winter months.

Symptoms/Signs: Leaf spot symptoms tend to vary with each pathogen/host pair. Spots range in size from very small (pinhead size), solid brown to purple lesions or spots to expanded lesions with bleached centers that girdle the leaf blade (Figure 1). Severely infected leaves turn purple or reddish brown in color, giving the turf an overall purple cast. Severely infected leaves eventually wither and dry to a light tan color. Lesions on stolons are dark purple to black. Distinct patches or patterns to the disease are usually not obvious. In cases of severe infection, turf areas thin and die.

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