Field application of bio-control agents for controlling fungal root rot and root-knot nematode in potato

Abstract

Six bio-control agents (BCAs) named Stanes sting® [Bacillus subtilis at 109 bacterial cells/ml], Bio-Nematon® [Paecilomyces lilacinus at 108 unit/cm3], Trichoderma hamatum, Trichoderma album, Stanes symbion vam plus® (Glomus fasciculatum and Gigaspora sp.) and Rhizo-N® [B. subtilis, 25 million bacterial cells/g] were applied in commercial potato field for controlling for root-rot disease caused by Fusarium solani and Rhizoctonia solani and nematode root-knot caused by Meloidogyne arenaria, compared to chemical nematicide of Nemacur (fenamiphos) [3-methyl-4-(methylthio) phenyl (1-methylethyl) phosphoramidate]. The BCAs highly increased the frequency of Aspergillus spp., followed by A. niger, compared to Penicillium spp., and Trichoderma spp., compared to the control. The BCAs significantly reduced the frequency of F. solani and R. solani, as well as the percentages of disease incidence of root rot in the rhizospheres of treated potato plants, compared to Nemacur® as well as the untreated plants. After two months of treatment, reduction of number of juveniles (J2) caused by BCAs in soil was in the range of 33.1–76.9%, compared to 16.9% with Nemacur®. After four months of treatment, the percentages of reduction of the total juveniles in soil and roots was in the range of 1.1–86.1%, compared to 24.5% with Nemacur®. Effect of BCAs on averages of plant height, number stems/pit and leaves per plant were determined after two months of planting, while their effect on yield parameters such as the average of tubers weight/pit, number of tubers per pit and average of tuber weight were determined at harvest.