The effect of carrier volume on ascochyta blight (Ascochyta rabiei) control in chickpea

Ascochyta blight of chickpea, caused by Ascochyta rabiei, can cause complete crop loss under favorable weather conditions. Fungicide applications are an important part of ascochyta blight management. Field and laboratory studies were conducted from 2001 to 2003 in Saskatchewan, Canada, to compare the efficacy of different carrier volumes (100, 200, and 300 L ha−1) for ascochyta blight control in the desi cultivar ‘Myles’ (fern leaf), and the kabuli cultivars ‘CDC Yuma’ (fern leaf) and ‘Sanford’ (unifoliate). In field studies, carrier volume was not critical under low to moderate disease pressure. Under high disease pressure where better fungicide coverage was required, higher carrier volumes significantly reduced disease severity. However, two fungicide applications were insufficient to protect the crop, thereby obscuring the effect of carrier volume, particularly in cv. ‘Sanford’. The laboratory study showed that higher carrier volume (>100 L ha−1) was more beneficial for penetration of the cv. ‘Myles’ canopy compared with the cv. ‘Sanford’ canopy.