COUGARBLIGHT 2010, A SIGNIFICANT UPDATE OF THE COUGARBLIGHT FIRE BLIGHT INFECTION RISK MODEL

The CougarBlight fire blight flower infection risk model was developed in the early 1990s following the rapidly evolving understanding of the infection process, limited scientific data on the growth rate of Erwinia amylovora (E.a.) relative to temperatures, and the study of weather conditions leading up to numerous isolated outbreaks of fire blight (Smith, 1993, 1999; Thomson, 1986). Rather than daily mean temperatures (Mills, 1956), hourly temperature values over the four day period leading up to flower wetness were measured to quantify infection risk.
Total temperature value accumulation necessary for infection thresholds were set up empirically.
The presence of fire blight or its recent history in the neighborhood was used to differentiate temperature value accumulation thresholds dependent on potential inoculum level.
Subsequent studies (Thompson and Gouk, 2003; Pusey and Curry, 2004) have supported the four day accumulation of temperatures, but relatively new research has provided an opportunity to improve the values assigned to various hourly and daily high temperatures as they relate to population sizes on flower stigmas.
Temperature values are now based on the increase in population size of the pathogen per hour on flower stigmas at any specific temperature, divided by 1,000. Total daily values for forecasting daily risk are based on an average of the sum of 24 individual hours relating to daily high temperatures of numerous example days.
The new version of the model will be called CougarBlight 2010, and can be found in its most current version on a website listed below.
While past versions of the CougarBlight model are still functional, this new version is recommended for all future risk assessment.

XII International Workshop on Fire Blight

T.J. Smith, P.L. Pusey

fire blight, model, infection, CougarBlight, CougarBlight 2010, apple, pear

https://doi.org/10.17660/ActaHortic.2011.896.45