A new damaging foliar disease of the world's worst weed, purple nutsed
ge (Cyperus rotundus), was found in the Brazilian states of Minas Gera
is and Rio de Janeiro. Isolates of a previously undescribed species of
Ascochyta were obtained from plants of C. rotundus showing symptoms o
f leaf scorch. The name Ascochyta cyperiphthora is proposed for this n
ew fungal pathogen of purple nutsedge. Inoculation of healthy plants o
f purple nutsedge with a conidial suspension of A. cyperyphthora (1.8
x 10(6) spores/ml) resulted in general necrosis of aerial parts within
3 days. A. cyperiphthora was reisolated from diseased tissues.