detection and fluctuations of plant pathogens in sugar factory’s waste and sugar beet fields irrigated with waste in kerman province

sugar beet roots and attached soil are usually transferred to sugar factories for processing ,then the roots are washed by pressurized water. muddy water as waste flows in canal and is used to irrigate fields. the possibility of occurrence and fluctuations of the pathogenic organisms in waste were studied in 2005. the samples were collected from waste water once a week. isolation of pathogens was done by a) citrus leaf baiting method and on parph selective medium, and common culture media such as pda, cma, ma, na and  wa, b) irrigation of sugar beet seedlings with waste water, c) bioassay with healthy sugar beet roots and d) cysts of nematode extracted from waste by sieves. different pathogens were isolated from waste such as  fusarium oxysporum, fusarium sp., rhizopus stolonifer, penicillium spp., aspergillus spp., pythium  aphanidermatum pythium sp., phytophthora cryptogea, ph.drechsleri, mucor sp. rhizoctonia solani,geotrichum sp., erwinia carotovora and cysts of heterodera schachtii.  pathogencity tests were done for each pathogen. at early periods of processing, recovered populations of  pythiaceae and erwinia carotovora were high, and in the last weeks of processing period population of penicillium spp., aspergillus spp., mucor sp. and geotrichum sp. were in high levels. populations of alternaria alternata، rhizoctonia solani and fusarium spp. were stable and cysts of heterodera schachtii were variable during processing period. these pathogens were also isolated from fields of sugar beet irrigated with waste water.