Studies on biology, epidemiology and control of Pseudocercospora pistacina in pistachio

Leaf spot disease, also known as “Karazenk”, is one of the most significant diseases affecting pistachio yield in Turkey. The causal agent has been recently renamed as Pseudocercospora pistacina Crous, Quadv. & Sarpkaya. In surveys conducted in 2009, 2010 and 2011 in Turkey, disease incidences were 47.5, 42.5 and 55.2%, respectively. The disease was seen less in the Turkish provinces of Gaziantep, Şanlıurfa and Siirt, which are major production areas in Turkey, than in other regions. Studies to determine the reactions of pistachio cultivars to Karazenk disease showed that female cultivars 'Kırmızı' and 'Uzun' and male cultivar 'Kaşka' were more susceptible than other cultivars, with ratios of 80.5, 78.9, and 73.7%, respectively. In vitro studies showed that initial infection required leaf wetness for at least 12 h, and temperatures of 24-30°C favored disease progression. In vitro and in vivo tests showed that copper oxychlorur and dodine were ineffective when applied after infection. However, propiconazole + difenoconazole was effective in controlling the disease even if applied after first symptoms were seen on the leaves