Fungal and oomycota species associated with citrus decline in Hormozgan provine

This study was conducted with the aim of isolation, identification, frequency determination and pathogenicity of fungal and oomycota species associated with citrus decline in six different locations of Hormozgan province. Isolation of fungi and oomycota was carried out from Bakraee and Mexican lime roots and local tangerine branches on general and semi-selective culture media. The isolates were identified at genus or species level based on morphological characteristics and sequence of ITS-rDNA and a part of TEF-1α gene. Frequency percentage of identified species was determined in surveyed locations based on numbers of cultivated plant pieces. Fusarium solani, Macrophomina phaseolina, Fusarium proliferatum, Alternaria sp., Rhizoctonia solani, Fusarium acutatum, Phoma sp., Fusarium sp.1 and Fusarium sp.2 with the frequency of 93.51%, 1.1%, 0.26%, 0.26%, 0.17%, 0.08%, 0.04% and 0.04%, respectively, and Pythium spp. and Phytophthora nicotianae with the frequency of 4.96% and 3.12%, respectively, were isolated from roots with rot. Fungal species isolated from branches with dieback symptoms were Alternaria spp., Neofusicoccum mediterraneum and Colletotrichum gloeosporioides with the frequency of 81.7%, 10.56% and 0.92%, respectively. Pathogenicity of three isolates from each species was tested on one-year-old seedlings of local tangerine on Bakraee. All the investigated isolates, except for Alternaria sp. and Pythium sp., were pathogenic on seedlings and caused symptoms similar to decline symptoms observed in citrus orchards. Pathogenicity of Alternaria sp.1 and N. mediterraneum isolates was tested on detached branches of local tangerine and pathogenicity of C. gloeosporioides was tested on one-year-old seedlings of local tangerine and all tested isolates were pathogenic.