Initial Investigation on Biological Control of Some Important Weed Species of Wheat Fields Using Rhizosphere Fusariums

In this research, the biological potential of rhizosphere Fusarium (Fusarium spp.) species to control some important weeds of wheat fields was studied. In the greenhouse, wild barely (Hordeum spontaneum), wild oat (Avena ludoviciana), rye (Secale cereale) wild mustard (Sinapis arvensis), and turnipweed (Rapistrum rugosum) seeds were planted on the soils sampled from wheat fileds of East Azerbayejan, Alborz, Tehran, North Khorasan, Razavi Khorasan, Khouzestan, Fars, Qazvin, Qom, Mazandaran, Kermanshah, Hamedan and Golestan provinces. Fusarium species of plants root were isolated. Effect of Fusarium isolates on seedling radicle length was considered as the criteria for successful control (inhibition of radicle length≥ 70%) in the bioassay experiments. In the first step of bioassay experiments, lettuce (Lactuca sativa) seedling was used as a test plant and the next step was carried out on mentioned weed species. Finally, wheat seedling of Sivand cultivar was used to evaluate the host specifity of selected isolates from pervious stages. Isolates with efficient inhibitory effects on weeds with least inhibitory (seedling radicle reduction≥ 10%) effect on wheat, were determined as successful selective biological control agents and identified with morphological and molecular methods. Results showed that one isolation of F. oxysporum on wild mustard and turnipweed, one isolate of F. brachygibbosum on wild barely and one isolate of F. equiseti on wild barely and wild oat, controlled the species very effectively. Knowledge about microbial agenets for biological control of weed species could be helpful in diversifying current management methods and maintenance of efficacy of available chemical herbicides.