Effects of Planting Pattern and Fungicide Application Systems on Ascochyta Blight Control and Seed Yield in Chickpea

Improved cultural practices can be used to manage ascochyta blight in chickpea (Cicer arietinum L.), a disease caused by Ascochyta rabiei (Pass.) Labrousse. This study examined the effect of planting pattern, seeding rate, and fungicide application systems on ascochyta blight severity and crop yield of chickpea at Swift Current (50 degrees 25'N, 107 degrees 44'W), SK, Canada, in 2004 and 2005. Crop was grown in uniform row (25 cm) and paired-row spacing (25 cm within each pair and 75 cm between pairs), at 44 and 31 plants m(-2), and with 1x and 0.67x the recommended fungicide application rates. Area under disease progress curve (AUDPC) averaged 1580 units for the susceptible cultivar CDC Xena, and significantly greater than 573 for the partially resistant cultivar Amit. The AUPDC value reduced from 750 at one fungicide application to 400 at four applications for Amit, and from 1907 to 1250 for CDC Xena. Seed yield was 2.24 Mg ha(-1) with four applications and 1.73 Mg ha(-1) with one application for Amit, and 1.04 and 0.18 Mg ha(-1), respectively, for CDC Xena. Paired-row spacing reduced AUDPC by 12% for Amit and 14% for CDC Xena from uniform row spacing. With paired-row spacing, blight severity did not differ between the 1x and 0.67x fungicide application rates or between the plant densities of 44 and 31 plants m(-2). Altered planting patterns, in combination with improved fungicide application systems, can potentially enable growers to reduce fungicide rates by 30% without decreasing efficacy of ascochyta blight control or seed yield for chickpea in northern Great Plains.