Southern Blight caused by Sclerotium rolfsii Sacc. resulted in loss
of many space planted plants of Lolium
multiflorum Lam. at Overton, Texas
in 2005.� This disease epidemic occurred
during April and May, when annual ryegrass plants were heading out.� The disease occurred on both forage-type
tetraploids plants as well as dwarf turf-type diploid plants.� Nurseries went through drought conditions,
followed by moist growing conditions with heavy dews.� Several days of warm weather with day time
temperatures near 34 C likely contributed to the epidemic.� A few plants begin to show brown to redish
leaves, followed by entire plants showing symptoms similar to drought or heat
stress and then death of plant over approximately 5 days.� Over a 10 day period, approximately 80% of
plants were heavily diseased in some nurseries.�
Healthy plants were observed adjacent to dead plants.� When inspecting the crown and roots system,
crowns were rotted and�
most roots had died.� Also
many white and brown sclerotia (1 to 2 mm) were
observed in the crown area of the plants.�
In adjacent pastures, where ryegrass was growing, the disease was not
observed.� The disease was also not
apparent in over seeded (annual and perennial ryegrass) turf plots.