Enhancing Pea Yields Through Improved Ascochyta Pisi Management - PulseResearch
April 25, 2017
Research in field pea shows management is possible
Ascochyta blight is considered a major impediment to pea production in Saskatchewan. However, recent research reveals that at least one of the pathogens that cause Ascochyta blight in peas may not pose as much risk as previously thought.
Didymella pinodes (D. pinodes) and Ascochyta pisi (A. pisi) are both causal agents of Ascochyta blight on pea. Generally, D. pinodes is considered to be more aggressive and common in Saskatchewan. However, significantly more A. pisi than D. pinodes has been recovered, found on seeds harvested in southern and southwestern cropping districts of the province during the past decade.
With that information in hand, along with funding from Saskatchewan Pulse Growers, Dr. Sabine Banniza from the University of Saskatchewan’s Crop Development Centre led a team of researchers to assess the relative importance of A. pisi in Saskatchewan field pea.
Objectives of the research included evaluating whether A. pisi and D. pinodes have different optimal temperature and moisture levels required for growth, assessing the role A. pisi plays on disease development in field pea, determining the yield loss caused by A. pisi, and finding a genetic control for A. pisi.
“Growth chamber experiments revealed that both pathogens have a temperature optimum at 20 to 25°C,” Banniza says. “Requirements for leaf wetness periods for infection are also similar, rejecting the hypothesis of different climatic optima for the two pathogens.”
Seed-to-seedling transmission was assessed on seed lots with between 0.5 and 14.5 per cent A. pisi infection in field experiments. Although higher seed infection levels of 10 and 14.5 per cent slightly reduced emergence compared to 0.5 per cent infection levels. Banniza says this did not translate to increased seedling infection, yield loss, or infection levels of harvested seed, and only affected final disease severity in one out of six experiments.
Yield loss studies were based on comparisons of fungicide treated and untreated plots of four pea cultivars. Low to moderate A. pisi levels resulted in significant differences in disease severity in only one of five experiments, which did not translate into yield differences.
“However, A. pisi infection levels of harvested seeds were higher in unsprayed compared to sprayed plots at Saskatoon and at Swift Current in 2014, where no significant differences in disease severity had been observed,” Banniza says. “Low and highly variable disease also impeded the genetic study, and significant differences between parents were only found when pooling all six experiments.”
High variability did not permit further analyses to determine genetic control of resistance to A. pisi, but the range of disease levels observed among recombinant inbred lines suggest that resistance may be controlled by more than one gene.
Banniza and her team looked at the potential for enhancing pea yields through improved A. pisi management. However, seed infection with A. pisi was shown to have no or minimal effects on pea crop establishment, disease development, or seed yield.
“Fungicide applications at low and moderate disease levels do not appear to have any benefit,” she says. “Understanding the control of resistance in pea is still of relevance and we will continue searching for better parents for such a study.”
SPG Investment: $119,672
Project Length: 3 years
Co-Funder: Agriculture Development Fun - $110,584
Project Lead: Dr. Sabine Banniza - Professor, Ministry of Agriculture Strategic Research Program Chair, Crop Development Centre, University of Saskatchewan