BIOLOGICAL CONTROL OF LEAF SPOT CAUSING FUNGAL PATHOGENS IN RED EDGE DRACAENA AND SOW THISTLE.

Leaf necrosis is a common fungal problem of plants. During a survey of Lahore, Dracaena Red Edge (Dracaena mariginata Lam.) and Sow thistle (Sonchus oleraceus L.) were infected with leaf spots. Pathogens isolation from the infected leaves of both plants was done followed by confirmation of Koch's pathogenicity postulates. Based on morphological and genetic characterization, Alternaria arborescens Simmons. and Phyllosticta aristolochiicola R.G. Shivas. were isolated from D. mariginata and S. oleraceus, respectively. In addition to isolation and identification, biological control of both pathogens was conducted using methanol extract of Cinnamon (Cinnamomum verum J. Presl.). All concentrations of extract suppressed the growth of both pathogens to variable extent. In case of A. arborescens, 0.5% concentration induced approximately 90% suppression in fungal growth. Contrastingly, P. aristolochiicola was least affected at lower concentrations of extract as only 4-10% arrest in fungal biomass production was recorded at 0.5-1.5% concentrations. However, 2.0% or more of the extract was most potent as fungal pathogens failed to grow at these concentrations. Therefore, Cinnamon extract was considered more effective in controlling A. arborescens than P. aristolochiicola. Further, studies are required to identify active antifungal compounds in Cinnamon crude extract against the target pathogens. [ABSTRACT FROM AUTHOR]