Understanding infection of pistachio by Colletotrichum acutatum
Anthracnose of pistachio (Pistacia vera) in Australia is caused by the fungus Colletotrichum acutatum. Black, sunken lesions develop on the fruit, often leading to severe shrivelling of kernels and hulls. Lesions with concentric circles occur on the leaf blade and black lesions on the mid rib of the leaves and on the peduncles and stems. A severe anthracnose outbreak, resulting in significant crop losses, occurred in the main pistachio growing areas of Australia following the unusually wet spring and summer of the 2010/11 season. To improve understanding of the conditions required to promote infection by C. acutatum, laboratory studies were conducted on detached pistachio leaves and fruit. The optimum temperature for growth and infection was 25°C. While infection occurred at 5°C, symptom expression was not evident until 10°C. Older fruit was more susceptible to infection than younger fruit. Infection of leaves and fruit occurred without humidity after inoculation, however, severity of infection increased following 12-24 h of humidity. These results showed that infection occurred in a wide range of temperature and humidity conditions. While some similarities exist between the infection of pistachio and other hosts by C. acutatum, there are enough differences to suggest that investigations into the specific epidemiology of anthracnose in pistachio are needed to assist with effective disease management.
Hall, B.H., Pederick, S.J. and McKay, S.F. (2016). Understanding infection of pistachio by Colletotrichum acutatum. Acta Hortic. 1109, 215-222