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For comparison of the infection index in treatments, the greenhouse experiment was performed with a split plot arranged in a randomized complete block design with four replications. Result of greenhouse experiments on different types of T. flavus treatments indicated that there was no significant difference among them. However, among five T. flavus isolates, the most effective one was Tf-To-V-24 and Tf-To-U-36. In the experiment on the interaction between different T. flavus treatments and T. flavus isolates, a minimum infection index was observed when both soil and seed were treated with Tf-To-V-31. The overall results of this study show that it may be possible to manage tomato Verticillium wilt disease effectively by T. flavus.

Verticillium wilt is considered the most important disease of cotton in the world, including Iran. Cultural practices and the use of resistant varieties are the most common strategies used to control Verticillium wilt of cotton. These strategies are not always available or effective. In recent years, biological control using fungal and bacterial antagonists, has been applied to control some cotton diseases including damping-off. In this study, we investigated the possibility of biological control of Verticillium wilt of cotton using bacterial antagonists. Suspension of eight bacterial strains of Pseudomonas fluorescens and Bacillus spp. isolated from different rhizospheric soils and plant roots in the Iranian cotton fields, were prepared with a concentration of 10 8 cfu/ml. Ten cotton seeds (cv Varamin) were then coated with each bacterial suspension and were planted in soil pre-inoculated with Verticillium dahliae microsclerotia. The efficacy of bacterial antagonists in reducing wilt disease was evaluated by determination of the disease index in different treatments. The results indicated that most isolates were effective in reducing disease (compared to the untreated control) 90 days after sowing. Isolates B5, B6, B2, B7, and B3 were the most effective, respectively, in reducing wilt index. In contrast, isolates B1, B4, and B8 did not significantly reduce the disease. In general, P. fluorescens isolates were more effective than Bacillus isolates. This study suggests that bacterial antagonists might be potential biological control agents of cotton.

Septoria tritici blotch (STB) caused by Mycosphaerella graminicola is a serious disease in some wheat-growing regions of Iran. Continuous monitoring of the fungus populations is indispensable to study the efficiency of known resistant cultivars and Stb genes. In this study, resistance of 49 wheat genotypes, including 20 wheat differential cultivars worldwide and 29 other wheat genotypes, were studied to 19 M. graminicola isolates. Among 931 genotype-isolate interactions, 224 isolate-specific resistances (26%) were observed by comparing the means of disease severity data using LSD 1% and LSD 5% . Iranian M. graminicola isolates showed new virulence patterns. All isolates were virulent to Stb2, Stb5, Stb6, Stb7, Stb13 and Stb14. Among wheat differentials, M3 was resistant to all isolates, indicating that it has gene(s) with the most efficiency against Iranian isolates. Among other genotypes, two genotypes were resistant to all isolates. This suggests that these genotypes have efficient resistance gene(s) to Iranian M. graminicola isolates and could be used as resistance sources to STB in Iran. They may be effective against other populations of M. graminicola worldwide.

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