Effect of planting date and host cultivar and three commercial microbial products on development of damping-off, root rot and wilt of soybean plants

Soybean (Glycine max (L.) Merr) is subject to stand injury and yield loss due to several diseases. Fusarium oxysporum, Macrophomina phaseolina, Rhizoctonia solani and Sclerotium rolfsii are found to be pathogenic to soybean causing damping off, root rot and wilt diseases. All isolates of the tested fungi were pathogenic but varied in virulence for pre and post- emergence damping off and their behavior. The highest level of pathogenicity was exhibited by R.solan. Chemicals are effective in controlling these diseases but, these chemicals are expensive and not environmental friendly. There are great efforts to reduce environmental pollution by reducing the dependence on agrochemicals to control pests. Biological control and resistant soybean cultivars are used means to control many diseases. Some microbial products such as Mycostop®, active microbial ingredient; Streptomyces griseoviridis; BioARC® Bacillus megaterium and Biozeaid ®, Trichoderma a/bum were evaluated as compared with the fungicide Rhizolex for their efficacy against Fusarium oxysporum, Macrophomina phaseoli, Rhizoctonia solani and Sclerotium rolfsii. , all tested microbial products or fungicide were significantly reduced the percentage of dampingoff, infested plants and increesed the percentage of healthy survival plants. Susceptibility of some soybean cultivars was tested in poto and under field condition. In pots experiment, none of the cultivars was completely resistant, however Giza 111 cultivar could be considered tolerant) while Gmza 22 cultivar considered the most susceptible one. Under naturally infested soil in the field conditions,(the reactions of seven cultivars (Giza 111, Giza 22, Giza 35, Giza 82, Giza2l, Kilarce and Crawford) to root-rot and wilt diseases complex were evaluated in two seasons. In 2006/2007 season Giza 111 had the least incidence % of diseases plants but Giza 35 cultivar had the highest one. In 2007/2008 season, the same trend was noticed with light grade. Plant weight and plant height did not correspond with the level resistance..