Etiology and incidence of pistachio endocarp lesion disorder in pistachio orchards of Kerman province, Iran

Pistachio endocarp lesion (PEL) is one of the most important disorders that has spread in the pistachio-growing regions of Rafsanjan and Anar in recent years and has caused great economic losses to farmers. In order to identify PEL symptoms, and investigate the biologic factors involved in the development of this disorder, on May 2016, 90 orchards with different levels of PEL, were randomly selected. The rate of development in each tree was scored in- to four levels. The incidence of this disorder was estimated to be 25.8% in Rafsanjan. The seeds with PEL symptoms were differentiated into six types based on the appearance of the symptoms. Then tissue from infected parts of each type were cultured in the PDA. From among the 18 prepared culture media, fungal growth was obtained only in five cultured plates. Isolated fungi were Ulocladium sp. Penicillium sp., Verticillium sp. and Fusarium sp. To prove their pathogenicity, the spore spray technique was used on detached cluster in vitro. None of the purified fungi caused symptoms similar to the symptoms of PEL. Isolated strains from the pistachio seeds with PEL symptom often were saprophytic and soil borne; they were abundant in the orchard and could be transferred to the shoots of trees under the influence of various factors, such as: tillage, soil splashing by rain drops, and wind. In this study, the role of these fungal agents on the development of PEL was rejected.