Crown and Root Rot of Birdís-foot Trefoil in Delaware Caused by Mycoleptodiscus terrestris. R. B. Carroll, Department of Plant and Soil Sciences, University of Delaware, Newark 19717-1303. D. P. Whittington, and E. R. Jones. Department of Plant and Soil Sciences, University of Delaware, Newark 19717-1303, and Department of Natural Resources, Delaware State College, Dover 19901. Plant Dis. 75:1074. Accepted for publication 26 May 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1074D.
A severe root and crown rot ofbird's-foot trefoil (Lolus corniculatus
L.) was observed near Dover, Delaware, in a trial to compare four
cultivars, with Viking the most susceptible and GAl the most resistant.
Symptoms and signs included limited regrowth, dead crowns, blackish
root lesions, and dark microsclerotia embedded in dead stems. Mycolepodiscus terrestris (J.W. Gerdemann) Ostazeski was isolated
consistently from diseased tissue (1,2). In replicated greenhouse tests,
an isolate of M. terrestris caused symptoms identical to those observed
on Viking. On a scale of 0-10, where 0 = no disease and 10 = plants
dead, the tests had a combined rating of 7.9, vs. 0.5 for controls.
Inoculated plants also had 50 and 34% reductions in root fresh weight
and top growth, respectively. In 1967, Ostazeski (2) isolated M.
terrestris from bird's-foot trefoil in Maryland and Virginia but did
not indicate disease severity. This is the first report of this disease
from Delaware and indicates its potential destructiveness on susceptible
cultivars in the mid-Atlantic region.