
TY  - JOUR
A1  - Villalta, O. N. 
A1  - Washington, W. S. 
A1  - Rimmington, G. M. 
A1  - MacHardy, W. E. 
T1  - Environmental factors influencing maturation and release of ascospores of <emph type="2">Venturia pirina</emph> in Victoria, Australia
JF  - Australian Journal of Agricultural Research
JO  - Aust. J.  Agric. Res.
Y1  - 2001
VL  - 52
IS  - 8
SP  - 825
EP  - 837
KW  - pear scab, ascospore maturity, epidemiology,Pyrus communis.
UR  - https://doi.org/10.1071/AR00093 
N2  - The influence of moisture, light, and temperature on Venturia pirina ascospore maturation and discharge was studied during 1992&#8211;99 in 2 pear-growing regions in Victoria. In each year and site, mature ascospores were trapped over a 3-month period beginning a few days before or at the green-tip stage of pear tree development in early September and ending in late November, with the majority of ascospores ((&#62;80%) trapped between green-tip and petal-fall. Ascospore discharge was associated with rain and dew, with 90&#8211;98% of the season&#8217;s total number of ascospores trapped during rain events and 2&#8211;10% trapped during dew events in the 12 data sets examined. Most ascospores were trapped (82.5&#8211; 99.9%) during daytime (0600&#8211;1800 hours). The 0.1&#8211;17.5% of ascospores detected during night time (1900&#8211;0500 hours) were trapped mainly within 1&#8211;3 h of dawn or dusk. There were linear relationships between the logit of cumulative percentage of ascospore maturation and temperature accumulation (above 0 degree-days), calculated both daily and for days with >= 0.2 mm of rainfall. Six linear regression equations were formulated with 10 years of field data and using the 2 methods of accumulating degree-days, to predict the cumulative percentage of matured ascospores. Predictions were compared with additional field and laboratory observations not used in the formulation of the linear equations. The importance of the temperature-based linear equations is discussed in relation to the prediction of pear scab ascospore maturity for use in a pear scab management program. 
ER  -

