Factors Affecting the Release of Ascospores of Anisogramma anomala

Abstract

Relationships between environmental factors and release of ascospores of Anisogramma anomala, the causal agent of eastern filbert blight, were examined in four European hazelnut (Corylus avellana) orchards during a 2-year period. In each orchard, Burkhard volumetric spore traps and automated weather-monitoring equipment were deployed for 12-week periods beginning at budbreak, when hazelnut becomes susceptible to infection. Ascospores of A. anomala were released when stromata on the surface of hazelnut branches were wet from rain but not from dew. Release of ascospores ceased after branch surfaces dried. The duration of free moisture on branch surfaces regulated the initiation and rate of ascospore release, but no significant effects of temperature, relative humidity, wind, or light on ascospore release were apparent. Most (>90%) ascospores were captured during precipitation events that exceeded 20 h in duration, which represented about 10% of the total precipitation events each season. Quantitative relationships between the hourly capture of A. anomala ascospores and hours since the beginning of a precipitation event were developed. With the onset of precipitation, the hourly rate of ascospore capture increased until the fifth hour of rain, remained relatively constant between the fifth and twelfth hours, and then declined gradually. During the 12-week spore-trapping periods, the likelihood and rates of ascospore release associated with precipitation were highest at budbreak and then declined through April and May until early June, when the reserve of ascospores in the perithecia was depleted. Large numbers of ascospores were captured in the volumetric spore traps, indicating that ascospores may be commonly dispersed long distances on air currents as well as locally by splash dispersal within the canopy, as reported previously. The results indicate that monitoring seasonal precipitation patterns may be useful for estimating the quantity and temporal distribution of airborne inoculum during the period that the host is susceptible to infection.

Impact of Weather on Sigatoka Leaf Spot of Banana (<i>Musa</i> spp. L.) and its Ecofriendly Management

“…The climate of Bangladesh harbors plant pathogen and provides luxuriant environment for the growth and reproduction of large number of plant pathogens which cause hundreds of different diseases of crops (Fakir, 2001). Determining the effect of weather parameters on the formation, release and germination of inoculum in different pathosystems have been focused by many researchers in worldwide (Pinkerton et al, 1998;MacHardy et al, 2001;Mondal and Timmer, 2002). Plant disease play an important role in reducing yield of horticultural crops in the tropics.…”

Microbiology and atmospheric processes: research challenges concerning the impact of airborne micro-organisms on the atmosphere and climate

“…This approach has hidden the nature of the particles with which these microorganisms are associated. From direct observation of airborne particles, we know that fungi in the atmosphere may be present as single spores or clusters (Aylor and Ferrandino, 1985;Bainbridge and Stedman, 1979;Pinkerton et al, 1998) or as fragments (Fuzzi et al, 2007). For bacteria, size-graded samples from Andersen spore samplers, for example, indicate that a large proportion of viable air-borne bacteria are associated with particles that are much larger than the size of single bacterial cells (Lighthart, 1997).…”

DNA markers linked to eastern filbert blight resistance in “Ratoli” hazelnut (Corylus avellana L.)

“…The pathogen is endemic in eastern North America where it causes small lesions on the wild American hazel (Corylus americana Marsh.). The pathogen's life cycle has been well documented (Pinkerton et al , 1998a(Pinkerton et al , b, 2001Stone et al Johnson et al 1996). Ascospores released from perithecia are dispersed by splashing rains, plus active discharge that occurs during prolonged periods of branch wetness.…”