Investigation of the effect of antagonistic fungi and weed control on the incidence of cotton Verticillium wilt and seedling damping-off diseases.

Verticillium wilt and seedling damping-off are cotton important diseases in the cotton fields of Iran. Currently, these diseases are controlled by using resistance cultivars and chemical fungicides such as carboxintiram. These compounds contaminate environment and result in new races of pathogens that are resistance to chemical pesticides. The search for alternative control strategies is therefore clearly obvious. 25 In this study, the effect of using antagonistic fungi and herbicides on two cotton diseases, Verticillium wilt and seedling damping-off and several cotton growth characteristics were investigated separately in Neishaboor and Moghan cotton fields . Each experiment was performed as a split plot arranged in a randomized complete block design with four replications. The main factor was using herbicides at three levels ( treflan, solanan and non herbicide ) and the subfactor was using antagonistic fungi at ten levels (1- soil and seed without inoculum, 2,3,4-soil without inoculum and seed coated with one of two antagonistic fungi, Trichoderma harzianum or Talaromyces flavus or both antagonistic fungi, 5,6,7- soil contained one of two antagonistic fungi or both antagonistic fungi and seed without inoculum, 8,9,10- soil and seed treated with one of two antagonistic fungi or both antagonistic fungi ). Results of Moghan field experiment showed that regardless of main factor, there were maximum pre-maturing percent and minimum Verticillium wilt disease percent in treatment contained seed coated with both antagonistic fungi. In this experiment, minimum seedling damping-off percent in treatment contained soil and seed contained both antagonistic fungi and minimum Verticillium wilt index as well as maximum yield in treatment affected with soil contained T. harzianum were observed. Regardless of subfactor, effect of main factor on total parameters was not significant. Results of intraction effects among main factor and subfactor showed that maximum significant disease decrease has been occurred in treatment affected with treflan herbicide and soil and seed contained T. flavus. Results of Neishaboor field experiment indicated that effect of main factor and subfactor was significant on yield and disease respectively. Result of effect of main factor on yield showed that there was maximum yield when solanan was used. However, result of effect of subfactor on disease showed that minimum percent of each disease occurred when soil was treated with T. flavus. Results of intraction effects among main factor and subfactor on percent of each disease and total yield was significant. In this experiment, minimum disease percent and maximum total yield were observed in treatment affected with solanan herbicide and soil contained T. harzianum.