Seasonal patterns of dispersal of ascospores of Cryphonectria parasitica (chestnut blight) |
| |
| Authors: | L Guerin G Froidefond X-M Xu † |
| |
| Institution: | ENITA de Bordeaux, 1 cours du Général de Gaulle, 33 175 Gradignan BP 201 cedex France;;INRA centre de Recherche de Bordeaux, Domaine de la Grande Ferrade, 33 Villenave d'Ornon BP cedex, France;and;Horticulture Research International, East Malling, West Malling;, Kent ME19 6BJ, UK |
| |
| Abstract: | Infected barks of chestnut blight cankers, caused by Cryphonectria parasitica , were collected from a naturally infected orchard and incubated at different temperatures. Cankers started to discharge ascospores about a week after incubation at 15–25°C; most ascospores were collected at 20 and 25°C. When incubated at 5, 10 or 30°C, only a few cankers released a small number of ascospores and only during the later stages of incubation. However, the rate of formation of perithecia was not affected by the incubation temperature. The number of airborne ascospores was monitored using a volumetric spore trap in a chestnut orchard during 1996 and 1997. In both years, the number of ascospores trapped daily varied greatly, but in general it increased sharply from March onwards, reached a peak in May, and then declined steeply. There was a significant correlation between daily counts of ascospores and air temperature. Time-series transfer function (TF) analysis showed a positive association of the daily number of ascospores with increasing temperature, rain events and wet/humid conditions. In general, values predicted by the TF model agreed well with the observed pattern. However, a multiple regression equation based on TF analysis failed to provide a satisfactory prediction of the daily number of ascospores. |
| |
| Keywords: | ARIMA model ascospores Chestnut blight Cryphonectria parasitica dissemination transfer function |
|
|
