Effect of tillage and residue management on damping-off and verticillium wilt diseases, yield and yield components of cotton (Gossypium hirsutum L.)

‏To study the effects of agronomic practices on incidence and development of damping-off and verticillium wilt diseases, yield and yield components of cotton, two field experiments were conducted in Karkandeh Cotton Disease Research Station, 35 Km west of Gorgan, Iran-using split plot arrangements in randomized complete block design with three replications. Autumn agronomic practices: 1- without agronomic practices as control, 2- chopper, 3- chopper + disk, 4- chopper + moldboard plow, 5- chopper + disk plow, 6- moldboard plow,7- disk plow were assigned to main plots. Spring agronomic practices: 1- moldboard plow + disk and 2- disk were randomized in sub-plots. Combined analysis of variances showed that damping-off and verticillium wilt incidences were severely affected by interactions of agronomic  tillage practices (autumn and spring tillages). Hence, moldboard plow × spring disk and (chopper + autumn moldboard plow) × spring disk had the least effect of incidence of pre-emergence damping-off and verticillium wilt diseases, respectively. The highest rate of incidence of damping-off disease due to Rhizoctonia solani was observed in chopper × spring disk package (62.5%). The highest and lowest seed cotton yield were obtained from (chopper + autumn moldboard plow) × (spring moldboard plow + disk), and (chopper + autumn disk) × (spring moldboard plow+disk), respectively. It is concluded that field establishment and reduce losses of damping-off and verticillium wilt diseases were significantly improved by implementation of the suitable agronomic practices for seedbed preparation in cotton production.