Plectosporium tabacinum Root Rot Disease of White Lupine (Lupinus termis Forsk.) and its Biological Control by Streptomyces Species

Plectosporium tabacinum root rot disease of white lupine is reported for the ®rst time in Cairo Governor- ate provinces. Symptoms of the disease appeared on young seedlings as stunting, yellowing and wilting of the foliage. Rotted roots were ®rst became light brown and the lesions progressively extended over the whole root system and became dark brown. Plants died when the whole root system had become infected. For suc- cessful biological control of the disease 70 rhizosphere actinomycetes were isolated by the use of normal stan- dard isolation techniques. Three of these isolates were found to be strongly antagonistic against P. tabacinum in vitro. They also signi®cantly reduced the incidence of white lupine root rot disease in soil infested with P. tabacinum in greenhouse trials. The three actinomy- cete isolates were identi®ed as Streptomyces cyanoviridis, Streptomyces murinus and Streptomyces griseoplanus