Pea root rot in Alberta: surveys, research and recommendations

Transcription

1 Pea root rot in Alberta: surveys, research and recommendations S. Chatterton, M.W. Harding and R. Bowness Agronomy Update January 21 st, Lethbridge, AB

2 Root rot development during late flowering Stunting, yellowing of leaf tissue Occurs in patches that expand over growing season 2

3 Field surveys in 2013 and fields/year, 10 sites/field, 5-10 roots/site = 15,500 roots Diagnostics assays for common pathogens Isolations and culturing 3

4 Disease severity rating scale Healthy Moderate Severe 4

5 170 fields surveyed in 2014 Prevalence = 100% Incidence = 72% Severity = 3.2 healthy moderate severe AAFC Agri-Geomatics Services 5

6 2013 Zone No. fields Incidence Severity ND ND ND Zone No. Fields Incidence Severity Root rot increased significantly from

7 7

8 8

9 Diagnosing root rot pathogens Diagnosing root rots is not an immediate fix as there are no effective in-crop treatment options Proper diagnosis aids in future crop management decisions Reveal trends among varieties, crop rotations, management practices that affect the soil or other inputs and stresses Supports researchers in breeding efforts 9

10 Different pathogens have different management implications Fusarium root rot caused by a complex of Fusarium spp. F. solani f.sp. pisi Produce long-lived resting spores in soil Specific to peas only F. avenaceum Survives on crop residue Broad host range Variation in aggressiveness of pathogens and isolates Photo courtesy of R. Bowness 10

11 Fusarium root rot symptoms 11

12 Aphanomyces euteiches: new pathogen for Alberta Water moulds Dependent on water for freeswimming zoospore stage Produces long-lived resting spores (oospores) No registered chemicals Very difficult to diagnose using conventional methods, requires a DNA test 12

13 13

14 14

15 A. euteiches in Alberta in out of 145 fields tested positive using a DNA test All in southern Alberta Vulcan Forty Mile Warner Wheatland Newell 15

16 A. euteiches in 2014 healthy moderate severe Significant increase from Improved DNA test detects lower pathogen numbers - Validated some fields with soil baiting tests - Fields positive for Aphanomyces root rot show a range of disease severity levels - Research to quantify pathogen levels in relation to root rot risk of Fusarium and Aphanomyces 16

17 17

18 18

19 19

20 Root rot symptoms in 2014 Symptom expression is not clear-cut, and most often roots are infected with a pathogen complex 20

21 Some thoughts about root rots Foliar fungicides will not work on root diseases Management aimed at prevention and avoidance Seed treatments are ineffective past the seedling stage Root rots are most severe under waterlogged conditions Crops can also suffer due to wet feet regardless of pathogen pressure 21

22 Seeding decisions to minimize root rot risk Plant good quality seed Use appropriate inoculant Germinating seeds most sensitive to initial Fusarium infection Use seed treatments if planting into cool soils and/or risk of Fusarium root rot Fusarium inoculum applied to 2-week old seedlings Fusarium inoculum applied at seeding 22

23 Crop rotations to reduce inoculum build-up 4+ years between susceptible pulse varieties/crops No resistant varieties of peas Resistant pulse crops to Aphanomyces: faba bean, chickpea, soybean Pea, cv. Meadow Lentils, cv. Dazil Alfalfa 23

24 Host range testing Faba bean, cv. Snowdrop Roots = 0/8 Oospores = No Dry bean, cv. CDC Sol Roots = 7/8 Oospores = No Soybean, cv. Prudence Roots = 0/8 Oospores = No 24

25 Research planned for 2015 Field trials: Seed treatments chemical and biologicals Cultivar performance in high risk fields Potential soil amendment options: Spent lime from sugar beet processing Phostrol Edge or trifluralin herbicides Continue field surveys to monitor for spread of Aphanomyces Developing risk assessment tool based on soil testing 25

26 More information Alberta Pulse Growers website: Winter 2015 issue of Pulse Crop News 26

27 Thanks! Sherri Strydhorst Carol Mueller, Scott Erickson Trina Dubitz Kristy Gibb, Jon Nielsen A lot of coop students 27

28