Abstract
A 5-year study (2002-2006) was carried out in two pear orchards
in northern Italy, by trapping air-borne ascospores of Venturia
pirina. Characteristics of 155 ascospore discharge events
(hour of the day, duration, ascospore number) and weather conditions
of the hours preceding the beginning of the discharge (WD,
wetness duration; R, rainfall; Tw, temperature during wetness)
were analysed with the aim of better defining environmental conditions
favouring ascospore discharge. Ascospore discharge showed
a diurnal periodicity, with the 92% of total spores trapped in daylight.
Thirty-seven percent of ascospore discharge events were triggered
by rainfall, 55% by leaf wetness, while 8% occurred under
dry conditions. The probability of ascospore discharge to occur
was calculated using a logistic regression procedure with a stepwise
selection of the independent variables. The variable ‘WD × Tw’
was selected as the most influential, while Tw, WD and R were not.
The logistic equation provides the probability of an ascospore discharge
to occur based on the combination of wetness duration and
average temperature during the wet period preceding the beginning
of the ascospore discharge. Probability was higher than 0.5
when ‘WD × Tw’ was higher than 197.5°C×h, while it was 0.9
when ‘WD × Tw’ was 585°C×h. This result showed that ascospore
discharge in V. pirina is mainly influenced by wetness and temperature,
while in V. inaequalis it depends mainly on rainfall. Calculation
of the infection periods for controlling pear scab should take
account of this difference.
Lingua originale | English |
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pagine (da-a) | N/A-N/A |
Numero di pagine | 1 |
Rivista | Journal of Plant Pathology |
DOI | |
Stato di pubblicazione | Pubblicato - 2008 |
Evento | 9th International Congress of Plant Pathology - Torino Durata: 24 ago 2008 → 29 ago 2008 |
Keywords
- Venturia pirina
- ascospore discharge
- weather conditions