ISHS Acta Horticulturae 704: X International Workshop on Fire Blight
WEATHER AFFECTING THE INCIDENCE AND SEVERITY OF FIRE BLIGHT IN ENGLAND |
| Author: | E. Billing |
| Keywords: | risk assessment, storm damage, secondary blossom, twig cankers, pre-bloom risks, post-harvest risks, over-wintering risks |
| DOI: | 10.17660/ActaHortic.2006.704.20 |
| Abstract:
In England, primary blossom blight on pears (Pyrus x communis) and apples (Malus x domestica) is rare and protective antibiotic sprays are not used. Alternative hosts such as hawthorns (Crataegus) and pyracanthas and cotoneasters can be important reservoirs of inoculum. For disease management, it is important to assess all risks from bud swelling to leaf fall on all hosts. Billing’s integrated system (BIS) provides a simple approach to risk assessment that has the advantage that the graphical presentation shows weather patterns throughout the growing season. The system allows for easy comparison of events within and between seasons and between areas. The main period of study was 1957-1982 when the best field records were available; experience in later years was used to test hypotheses developed earlier. Some risk studies were supplemented with greenhouse experiments. Weather-related risks considered include: cross-infection between hosts, over-wintering, pre-bloom and early bloom risks (frost and storm effects), factors favouring pear secondary and post-harvest blossom production, shoot blight, late summer stem invasion and post-harvest twig blight. The sum of degree-days above 18°C plus a wetting event usually gave useful guidance on blossom blight risks but other weather-related factors were important for disease persistence. Damaging storms (especially night storms) seemed to play an important role. Apart from increasing blossom and shoot blight incidence and severity, they favoured pre-bloom and post-harvest disease and could promote post-harvest blossom on pears. For early disease detection and for good disease management, full details of the characteristics of each storm are needed. More studies are needed in the pre-bloom and the post-harvest periods to ensure that any preventative and control measures are used to best advantage. | |
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