By John Ippolito, PAg, Crops Extension Specialist, Kindersley
Each year during the growing season, the Saskatchewan Ministry of Agriculture joins a number of industry partners to conduct numerous crop disease surveys. The purpose of these surveys is to monitor the prevalence of known plant diseases and the spread of new diseases that may be emerging. The information gathered from these surveys is then used to identify research needs, assist industry in identifying needs for crop protection and advise growers on what diseases to scout for in their own fields.
In 2020, we conducted disease surveys on peas, lentils, canola, flax, soybeans and cereal grains for the respective diseases that may impact those crops. Although the number of clubroot-infected canola fields is small, there are more being found each year. Root rots in peas and lentils are at relatively high levels and so are the foliar diseases of these two crops. Prevalence of blackleg in canola is higher than it has been in past years and some regions have blackleg present in almost every field surveyed.
In canola, there were two separate disease surveys conducted. The general canola disease survey examined plants in 261 fields for all diseases, including clubroot. Significant findings showed blackleg was found in 81 per cent of fields surveyed and an average of 15 per cent of plants in surveyed fields had blackleg symptoms. The average severity of the infection was low, at less than one on a scale of one to five. Sclerotinia stem rot was observed in 79 per cent of fields surveyed with an average incidence (number of infected plants) of 17 per cent, which is higher than had been observed in 2019.
There was a separate survey of 474 canola fields for clubroot. The survey found 10 fields that exhibited visual symptoms and an additional 18 fields without visible symptoms where the pathogen was detected through DNA testing. In addition to these fields, eight fields with visual symptoms were reported by producers or agronomists. Currently, there are 75 fields in Saskatchewan that have had plants exhibiting visual symptoms (since the clubroot survey began in 2017).
Field peas were surveyed for both foliar diseases and root rots. All of the fields surveyed had plants with root rot with a relatively high incidence of 61 per cent of plants examined showing symptoms. However, severity (amount of disease on each plant) was low. Mycospherella blight was also present in all the fields surveyed with an average incidence of 83 per cent.
Anthracnose was present in 84 per cent of lentil fields that were surveyed with an average incidence of 44 per cent of plants per field with visual symptoms. Root rots in lentils were not quite as prevalent as peas but were observed in 71 per cent of the surveyed fields. Stemphylium blight is a lentil disease that is gaining more attention recently as it may impact ease of splitting of the lentils. This disease was found in 70 per cent of the surveyed fields.
Cereals were surveyed for leaf diseases and fusarium head blight. Currently there are only very preliminary results available from this survey, so they will be reported at a later date.
The Ministry of Agriculture is currently addressing the findings of these surveys through the funding of research and delivery of technology transfer activities. There are a number of research projects that are ongoing or starting in 2021 that are related to plant diseases. These include plant breeding for disease resistance in peas, lentils, flax and chickpea. New projects are focused on aphanomyces in peas, anthracnose in lentils, ascochyta in chickpea, methods to identify clubroot pathotypes, and use of remote imagery to identify and map clubroot infestations.
The understanding of the specific disease biology and appropriate management practices are shared through technology transfer activities, including on-line information, webinars and social media. A portion of the 2021 Crop Diagnostic School will cover management of clubroot and new technologies that can be used in decision making for fungicide applications for sclerotinia in canola.
Consider the disease survey results as you plan for your 2021 crop. If you wish to learn more about a specific disease, or are willing to participate in the surveys, contact your regional crops extension specialist or contact the Agriculture Knowledge Centre at 1-866-457-2377. Information on specific crop diseases is also available on-line.
We are always looking for growers willing to participate in these surveys by providing access to their fields. If you wish to learn more about the surveys or are willing to participate in the surveys by allowing access to your fields, visit our pest monitoring web page.