By Dale Risula, Provincial Specialist, Special Crops; Barb Ziesman, PhD, A.Ag, Provincial Specialist, Plant Disease; and Sherrilyn Phelps, PAg, Agronomy Manager, SaskPulse
High levels of insensitivity to Group 11 (strobilurin, QoI) fungicides in anthracnose were recently confirmed from Saskatchewan lentil fields. These fields were assessed because they had a high risk of developing insensitivity (also known as resistance) in the anthracnose pathogen (Colletotrichum lentis).
Monitoring for Group 11 insensitivity in the anthracnose pathogen was initiated in response to a report of low field performance by a Group 11 product. As part of due diligence, BASF sent anthracnose samples for resistance screening; the G143A mutation, which confers cross resistance to all Group 11 fungicides, was confirmed. In 2019, a collection of anthracnose samples from a number of fields with a history of fungicide use, tight lentil rotations and heavy disease pressure resulted in detection of insensitive populations of the pathogen across the Saskatchewan lentil growing region. These fields had increased risk for insensitivity in the anthracnose pathogen, and do not represent a random survey. Additional testing and monitoring is needed to understand the extent of insensitivity in anthracnose in Saskatchewan.
Growers can minimize anthracnose severity and risk of developing insensitivity by using recommended rotations (one in four years) and planting seed with low infection levels. Fungicide applications should follow the Fungicide Resistance Action Committee recommendations below, which are established to maximize fungicide effectiveness and minimize crop loss due to insensitivity in the pathogen:
- Scout fields regularly in-season;
- Apply fungicides according to label rates and timings;
- Minimize the use of Group 11 fungicides;
- Use fungicides that include actives other than Group 11 and are effective on anthracnose; and
- Scout fields at crop maturity to determine if fungicide applications were effective.
See the most current Guide to Crop Protection for details on foliar fungicides or SaskPulse's fungicide sheet for lentils.
Good agricultural practices to reduce the risk of resistance reinforce the necessity of the agricultural sector to work together to maintain the efficacy of available technologies. A task force has been established and is the first step in bringing expertise together to develop common messaging and recommendations. Look for more information in the near future.
For more information or if you have any questions, please contact Dale Risula, provincial specialist – special crops, or Barb Ziesman, provincial specialist – plant disease.