• Peas
• Disease Management
• University of Saskatchewan

Objective

To evaluate whether A. pisi and M. pinodes have different temperature and moisture optima. To assess the role of seed infection with A. pisi on disease development in field pea. To assess yield loss due to A. pisi in a selection of European and Canadian field pea cultivars under field conditions. To determine genetic control of resistance to A. pisi.

Outcome

Didymella pinodes (syn. Mycosphaerella pinodes) and Ascochyta pisi are both causal agents of ascochyta blight on pea. Growth chamber experiments revealed that both pathogens have a temperature optimum at 20 to 25°C. Requirements for leaf wetness periods for infection are also similar, rejecting the hypothesis of different climatic optima for the two pathogens. Although higher seed infection levels of 10 and 14.5% slightly reduced emergence to 0.5% infection levels, this did not translate in increased seedling infection, yield loss, or infection levels of harvested seed. Yield loss studies were based on comparisons of fungicide treated and untreated plots of four pea cultivars. Only low to moderate A. pisi levels resulted in significant differences in disease severity in only one of five experiments, which did not translate in yield differences. However, A. pisi infection levels of harvested seeds were higher in unsprayed compared to sprayed plots at Saskatoon in 2014, and at Swift Current where no significant differences in disease severity had been observed. Low and highly variable disease also impeded the genetic study of RIL population PR‐10, and significant differences between parents were only found when pooling all six experiments. A high coefficient of variability did not permit further analyses to determine genetic control of resistance to A. pisi, but the range of disease levels observed among RILs suggest that resistance may be controlled by more than one gene.

Download PDF Summary