A NEW DIEBACK DISEASE OF THE FORAGE LEGUME STYLOSANTHES-GUIANENSIS INSOUTH-AMERICA

A wilt and eventual dieback disease of the forage legume Stylosanthes guianensis, which occurs widely in Colombia and Brazil, is described. The causal agent of the wilt disease is identified as Lasiodiplodia th eobromae, a virulent, unspecialized, facultative wound pathogen with w orldwide distribution and more than 500 different host plants. The l-s eptate conidia are slow maturing, brown, thick walled, and striate. Ge notypes of S. guianensis vary in their reactions to the pathogen. Of e ight important S. guianesis genotypes tested for their reaction to the pathogen, the Brazilian cultivar Mineirao was the most susceptible, a nd CIAT 10136 and FM 9405 parcela 1 were the most resistant.