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 first time in Cairo Governorate provinces. Symptoms of the disease appeared on young seedlings as stunting, yellowing and wilting of the foliage. Rotted roots were first 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 successful biological control of the disease 70 rhizosphere actinomycetes were isolated by the use of normal standard isolation techniques. Three of these isolates were found to be strongly antagonistic against P. tabacinum in vitro . They also significantly reduced the incidence of white lupine root rot disease in soil infested with P. tabacinum in greenhouse trials. The three actinomycete isolates were identified as Streptomyces cyanoviridis , Streptomyces murinus and Streptomyces griseoplanus .