Blackleg Yield Loss Calculator

Severity Ratings

0 1 2 3 4 5
Blackleg 0 Blackleg 1 Blackleg 2 Blackleg 3 Blackleg 4 Blackleg 5
No disease visible in cross section. Diseased tissue occupies 25% or less of cross section. Diseased tissue occupies 26-50% of cross section. Diseased tissue occupies 51-75% of cross section. Diseased tissue occupies over 75% of cross section.
Plant is not dead.
Diseased tissue occupies 100% of cross section.
Tissue dry and black.
Yield Loss
0
Yield Loss
17%
Yield Loss
34%
Yield Loss
52%
Yield Loss
69%
Yield Loss
86%
  • Blackleg Severity Rating: 0

    No disease visible in cross section.

    Yield Loss: 0

  • Blackleg Severity Rating: 1

    Diseased tissue occupies 25% or less of cross section.

    Yield Loss: 17%

  • Blackleg Severity Rating: 2

    Diseased tissue occupies 26-50% of cross section.

    Yield Loss: 34%

  • Blackleg Severity Rating: 3

    Diseased tissue occupies 51-75% of cross section.

    Yield Loss: 52%

  • Blackleg Severity Rating: 4

    Diseased tissue occupies over 75% of cross section.
    Plant is not dead.

    Yield Loss: 69%

  • Blackleg Severity Rating: 5

    Diseased tissue occupies 100% of cross section.
    Tissue dry and black.

    Yield Loss: 86%

Blackleg Incidence

%

Blackleg Severity

(severity rating 0 - 5 from table above)

Please use a number between 0 and 5

Average Canola Yield

bu/ac

Potential yield loss due to blackleg:

{{ ((severity*1) * 17.2 * (avgyield*1) * (incidence*1) / 10000).toFixed(1) }}
bu/ac

Keep blackleg out of your canola.

Learn more
X
  • Blackleg Severity Rating: 0

    No disease visible in cross section.

    Yield Loss: 0

  • Blackleg Severity Rating: 1

    Diseased tissue occupies 25% or less of cross section.

    Yield Loss: 17%

  • Blackleg Severity Rating: 2

    Diseased tissue occupies 26-50% of cross section.

    Yield Loss: 34%

  • Blackleg Severity Rating: 3

    Diseased tissue occupies 51-75% of cross section.

    Yield Loss: 52%

  • Blackleg Severity Rating: 4

    Diseased tissue occupies over 75% of cross section.
    Plant is not dead.

    Yield Loss: 69%

  • Blackleg Severity Rating: 5

    Diseased tissue occupies 100% of cross section.
    Tissue dry and black.

    Yield Loss: 86%

Article - (Plants (Basel) 2016 Sept 5(3):31.

Blackleg (Leptosphaeria maculans) Severity and Yield Loss in Canola in Alberta, Canada.

Sheau-Fang Hwang, Sephen E. Strelkov, Gary Peng, Hafiz Ahmed, Qixing Zhou, and George Turnbull

  • Severe epidemics of blackleg can result in significant yield losses.
  • Understanding disease-yield relationships is a prerequisite for measuirng the agronomic efficacy and economic benefits of control methods.
  • Field experiments with susceptible and resistant cultivas (soil inoculated with blackleg were conducted in 2013, 2014, 2015 to determine the relationship between blackleg disease severity and yield in a susceptible cultivar and in moderately resistant to resistant canola hybrid.
  • Disease severity was lower, and seed yield was 120%-128% greater, in the moderately resistant to resistant hybrids compared with the susceptible cultivar.
  • Seed yield per plant decreased by 1.8g for each unit increase in disease severity, corresponding to a decline in yield of 17.2% for each unit increase in disease severity.
  • These results show that the reduction of blackleg in canola crops substantially improves yields.
Blackleg incidence: the percentage of infected plants in that field.
(based on 10-15 sample areas)
Blackleg severity of infected plants: Average severity of all infected plants in the samples clipped. Severity field only accepts numbers between 0 and 5 (decimal places allowed) and are based on the severity rating images.