Evaluation of four fire blight-tolerant pear cultivars and selections for commercial pear production in Canada.
Hunter, D.M. and Slingerland, K.C. (2008). "Evaluation of four fire blight-tolerant pear cultivars and selections for commercial pear production in Canada.", Acta Horticulturae (ISHS), 800(Part 1), pp. 541-545.
'Bartlett' has been the standard pear cultivar in the province of Ontario, Canada, for many years. A CanAdapt-funded project was established in 1998 to evaluate the fresh market and processing potentials of new cultivars and selections with improved tolerance to fire blight, and compare them to the standards 'Bartlett' and 'Swiss Bartlett'. In 1999, four selections from the AAFC breeding program [HW616 (now 'AC Harrow Gold™'), HW610 (now 'AC Harrow Crisp™'), HW614 and HW620], were planted in commercial orchards at five different sites in Ontario with varying soils and climates. In 2006, 'AC Harrow Crisp™', HW614 and HW620 had the largest trunk circumference while 'Bartlett' was the fifth largest. In 2005, the growing season was ideal for the spread of fire blight, and all sites were assessed for fire blight infection on a 1-9 scale, where 1 was the poorest score (severe infection) and 9 the best (little or no infection). Over the five sites, fire blight was most severe on 'Bartlett' (6.0) and 'Swiss Bartlett' (6.8), while the other four cultivars and selections ranged from 8.2 to 8.7. Accumulated yields have been highest on the late ripening selections HW614 and HW620. After four harvest years, 'Swiss Bartlett' had the smallest average fruit size (138 g) while HW620 had the largest fruit (215 g). 'AC Harrow Gold™', 'AC Harrow Crisp™', HW614 and HW620 have performed well for trunk circumference growth and tolerance to fire blight, while HW614 and HW620 have also produced good yields and large-sized fruit. Processing trials have identified 'AC Harrow Gold' and 'AC Harrow Crisp' as suitable for inclusion in plantings for commercial processing, while HW614 and HW620 are considered suitable only for the fresh market.