A recent pulse agronomy webinar hosted by Saskatchewan Pulse Growers (SPG) focused on an emerging chickpea issue found in southwestern Saskatchewan.
The presentation was spearheaded by Dr. Michelle Hubbard, research scientist in pulse pathology, who, in conjunction with other researchers, is leading studies on the issue.
The as-of-yet unnamed health issue was first observed in the 2019 growing season, and showed up again in 2020. The Gravelbourg, Assiniboia, and Coronach growing areas were worst hit by the suspected disease in 2019. In 2020, it seems that the disease has also spread outside of that region, as mild symptoms were also found near Swift Current.
Hubbard lead surveys of over 50 fields in the southwestern area of the province in 2020, and samples were taken by Sask Ag staff and private company agronomists to examine crops for ascochyta blight. SPG lead surveys investigating the emerging issue and Hubbard and the rest of the researchers left no stone unturned. Environmental conditions, herbicide residue or carryover, other diseases present, insect pressure, and soil nutrient issues have all been examined, which have helped to narrow down the scope of research and to hone in on problems that might contribute to crop failure.
Symptoms of the new disease started to appear from flowering to early podding stage and include leaf-tip chlorosis, variable leaf chlorosis or spotting throughout a leaflet, leaf death, and discolouration of new growth. Hubbard observed whitening of new leaves and even purple or brown tips in new growth. The issue can occur in patches, usually in low spots or where soil has been compacted, but also can be evenly distributed across a field.
Healthy and unhealthy roots were found on infected plants during the survey. In some cases, nodule growth would stop, and the inside of nodules were green, meaning there was no active nitrogen fixation.
Plant samples were tested for a wide range of pathogens, but there were no significant differences between healthy and unhealthy samples in terms of either the presence or absence, or the abundance of pathogens, says Hubbard.
“We did find many pathogens. They just didn’t meet the criteria of being present in a higher percentage of unhealthy samples than healthy ones, or having higher levels in unhealthy samples as compared to healthy samples. A next step will be to use molecular techniques to scan for what microbes (including pathogens) are in the soil. Drs. Jennifer Town and Tim Dumonceaux of Agriculture and Agri-Food Canada, Saskatoon, will be doing this,” Hubbard says.
It is very possible that this emerging health issue is the result of multiple compounding factors, such as the ones included in the surveys.