ISHS Acta Horticulturae 273: V International Workshop on Fireblight
PREDICTING CANKER, SHOOT AND TRAUMA BLIGHT PHASES OF APPLE FIRE BLIGHT EPIDEMICS USING THE MARYBLYT MODEL |
| Author: | Paul W. Steiner |
| Abstract:
MARYBLYT is a comprehensive model for predicting all phases of apple fire blight epidemics: blossom, canker, shoot and trauma blight. Systemic canker activity (SCA) begins routinely with the accumulation of at least 72.2 degree days (DD) >12.7C after green tip and only rarely occurs before petal fall. Canker blight symptoms (CBS) follow SCA regularly at 122.2 DD>12.7C after green tip as the result of internal movement of E. amylovora into limbs and shoots adjacent to active canker sites. If suitable insect vectors are present when either CBS or blossom blight symptoms appear, then shoot blight symptoms can be expected within an additional 50 DD>12.7C. Following hail or late frost incidents that occur after at least 300 degree hours > 18.3C have accumulated, a similar 50 DD interval is observed before trauma blight symptom appearance. Forecasts based on these thresholds and intervals have been generally reliable within one day. | |
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