In recent years, similar symptoms to sheath rot complex (SH C) and grain discoloration (GD) has been observed in paddy fieldsPathogenic strains were often isolated from samples with the symptom of longitudinal brown to reddish brown necrosis 5 mm wide extending the entire length of flag leaf sheath. Over 800 strains were isolated from collected samples and tested for pathogenicity on rice and/or hypersensitivity on tobacco or pelargonium. Pathogenic strains were isolated from 20.28% samples which contained only 5.3%of total strains. Eighty two strains comprising 72 strains from plants showing symptoms of sheath rot and grain discoloration, five strains from diseased seedling and five standard strains were analyzed for phenotypic studies. Pseudomonas-specific primers were used to confirm identification of the genus.On the basis of phenotypic characters and genus specific primers, the strains belonged to genera Acidovorax and Pseudomonas. Cluster analysis of 67 biochemical characters grouped 70 selected strains into seven distinct cluster and six groups with one member. The results confirmed that pathogenic strains associated with SH C and GD in Iran (Mazandaran province) belong to Acidovorax avenae subsp avenae (2.32%), Pseudomonas putida (2.32%), Pseudomonas marginalis (6.65%), Pseudomonas syringae (76.7%) and two unidentified species of Pseudomonas (13.95%). Accordingly, the P. syringae was revealed that is the major causal tnega of SH C and GD in north of Iran.

Determining the number of suppliers chosen for cooperation in a supply chain is one of the most important problems in the supply chain management area. Regarding the fact that simultaneously decreasing the risk and cost is one of the most important objectives of every organization, besides the cost, the risk has also been introduced in the recent researches, as one of the most important criteria. In this paper, the decision tree approach is used for determining the optimal number of suppliers considering the supply risk and it has been tried to develop an applied method through expanding the cost criteria. The proposed model in this paper, therefore, contains any kind of cost ingredients such as cost of suppliers development, cost of suppliers management, cost of missing discount in volume due to increase in number of suppliers in supply base, and loss cost due to supply postponement from suppliers. This approach is implemented in Emersun Company.

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