Naz, a resistant cultivar on bean root rot disease in Zanjan province, northwest Iran.

Field bean is a major crops in different parts of northwest Iran especially Zanjan province. Recently the bean plants were severely subjected to damping off or decline disease which caused yield losses in bean growing regions. A regional research was done from 2003 to 2005 to get general information on the causal agent of disease and its control management. Infected plants were collected from different studied areas and transferred to laboratory. Crown and plant roots were cultured in PDA as common media and PPA as selective media for Fusarium species after surface sterilization with sodium hypochlorite. Plates were incubated in standard culture room then isolated fungi were identified. Different Fusarium species were isolated, however the main pathogen isolated from plant samples and soil around the roots was F. sambucium Fuckel. The disease caused up to 50% yield losses in some fields in studied areas. Study showed the "Naz" cultivar was the main resistant race to the disease and had the most yield production in the field.

Identification of anastomosis group of Rhizoctonia solani, the causal agent of seed rot and damping-off of bean in Iran.

Bean is one of the major crops in Iran. Seed rot and damping-off caused by Rhizoctonia solani is the most important disease of bean. In this research, infected roots and seedlings of beans were collected from different fields of Tehran Province. The samples were sterilized with 10% sodium hypochloride (5% stock) and incubated on PDA surface in petri-dishes. The purified fungi kept on filter paper and identified, pathogenicity test of R. solani was carried out on 2 cultivars of bean (red bean cv. Naz and white bean cv. Dehghan) and it determined. For identification of the anastomosis groups, the discs of cultured media with 5 mm. diameter of standard AG placed on one side of microscopic slides covered with water agar (2%) of 1 mm. thick and the isolates of the fungus on another side of slide about 2 cm away from each other. Experiment carried out in 4 replications. The cultures were incubated in 25 +/- 1 degrees C incubator for 24 hours, then the mycelial contact stained with lactophenol, cotton blue and hyphal anastomosis looked for under the light microscope with 10 x 40 and 10 x 100 magnifications. As a result, anastomosis groups: AG4, AG4HGII, AG2-2-2B and AG6 determined, frequency of these groups were 64, 18, 2, 16%, respectively. The group AG6 and subgroups AG4HGII and AG2-2-2B are introduced as new anastomosis groups on bean in Iran.