Abstract:
Green cumin)Cuminum cyminum L( . is considered one of the important crops in terms of exports and income worldwide and its cultivation widely spreading in Sudan. The crop is seriously damaged and the yield is radically reduced due to infection by Powdery mildew incited by the fungus Erysiphe polygoni. The present study was undertaken under field conditions at Dongula Research Station farm of the Agricultural Research Corporation (ARC), in Northern State during season 2014-2015, to investigate the bioactivity of crude aqueous extracts of Argel, Sodium bicarbonate solution and efficacy of fungicide (Jiamyl 50 WP), against powdery mildew disease in cumin and on yield of this crop. Two concentrations of aqueous extract of Argel, each of 60 and 20g/l and NaHCO3 solution at concentrations of 2.0 and 1.5g/l and fungicide at 0.5 g/l in addition to control were used. Treatments were arranged randomly in Randomize Complete Blok design replicated three times. Spraying of doses was done twice, 60 days after planting at 7 days interval. The assessment of effect of treatments on Powdery Mildew disease and yield was recorded through the percentage of disease incidence and severity and yield as Kg/f. The results showed that the spraying of aqueous plant extracts of Argel, NaHCO3 solution and fungicide at all concentrations were invariably highly effective in reducing the percentages incidence, severity of Powdery Mildew disease and increased the yield of the cumin crop compared to control. Among all treatments, the significantly least percentage disease incidence of 31.0%, severity of 0.8%, and highest yield of 253.5K/f were obtained by fungicide at 0.5 g/L followed by Argel of 33.3% (disease incidence), 1.5% (severity) and 186.4 Kg/f (yield) at 60g/l then NaHCO3, 35% (disease incidence), 1.1% (severity) and 198.7 Kg/f (yield) at 2.0g/l compared to control 98.3% incidence, 2.8 % severity and 130.7 kg/f yield. However, Argel aqueous extract and NaHCO3 solution exhibited an increased efficacy with increasing concentration. Moreover, the current results were considered promising and encouraging for to further studies to optimize the time of application and dose of Argel and NaHCO3 salt for Powdery Mildew diseases control.
