To assess the proportion of lentil fields in Saskatchewan with Colletotrichum lentis insensitive to group 11 fungicides.Objective 4
To examine the within field distribution of anthracnose with / without sensitivity to group 11 fungicides.
To assess the proportion of lentil fields in Saskatchewan with Colletotrichum lentis insensitive to group 11 fungicides; to assess sensitivity to group 3 and group 7 fungicides in the C. lentis population; to explore how an initial fungicide application impacts group 11 insensitivity in C. lentis; to examine the within field distribution of anthracnose with / without sensitivity to group 11 fungicides.
Anthracnose of lentil, caused by the fungal pathogen Colletotrichum lentis, is an important foliar disease on the Canadian Prairies. Management of this disease relies heavily on fungicides. Strobilurin fungicides (FRAC group 11 active ingredients) are a component of many of these products. However, insensitivity to strobilurins has been reported in C. lentis in Saskatchewan. This project examines the frequency and geographical distribution of strobilurin insensitivity in C. lentis, as well as anthracnose incidence and severity in commercial lentil fields in Saskatchewan. The role of landscape position (e.g., hill tops, midslope or flat areas, or low spots) and agronomic factors on disease were also explored.
The impact of strobilurin insensitivity on pathogen in vitro radial growth was measured. In addition, a preliminary assessment of insensitivity to the active ingredients benzovindiflupyr and fluopyram (FARC group 7) was conducted. Insensitivity to strobilurins was common across the lentil production area in 2022, as observed in 2020 and 2021. However, this trait did not affect anthracnose severity in commercial fields or growth of isolates in the absence of a fungicide. This indicated that strobilurin insensitivity was not linked to fitness of the pathogen. Anthracnose was more severe in low spots in fields than on hilltops, likely because humid conditions for infection persist longer in low spots. There was no evidence of insensitivity to group 7 fungicides in the preliminary assessments. Difficulties inducing sporulation in C.lentis isolates continues to be a challenge in this project.