Abstract
The yield of vegetables is reducing gradually every year due to the soil-borne pathogens (fungi and nematodes). Soil borne plant diseases cause significant damage to almost all crops particularly to the vegetables. Important plant soil-borne fungi which cause significant losses are Pythium spp., Phytophthora blight, Fusarium oxysporium, Leveillula taurica, Macrophomina phaseolina, Rhizoctonia solani, Alternaria spp. and some important nematodes were recorded for losses. During our survey conducted during July 2010 to December 2012 it was observed that in the vegetable crops of different areas of Sindh Province including Karachi (Malir, Sharafi Goth, Memon Goth and Gadap Town), Kunri, Mirpurkhas, Ghotaki, Tando Allahayar and Digri show heavy losses and several symptoms including wilting, stunted growth, chlorosis and blotch on vegetables crops. Diseased plant specimens were collected and brought to laboratory. The soil borne fungi Rhizoctonia solani, Macrophomina phaseolina and Fusarium oxysporum were isolated from the roots of brinjal and spinach plants collected from these areas. In antagonistic activity, four antagonistic fungi Aspergillus flavus, A. niger, Penicillium commune and Trichoderma harzianum isolated from the roots of vegetables were used against the above mentioned plant pathogenic fungi which successfully suppressed the activity of pathogenic fungi. In addition, it disclosed that Aspergillus niger was highly antagonistic towards R. solani, M. phaseolina and F. oxysporum as it showed a strong inhibitory effect on the growth and mycelial development.
