توصيفگر ها :
پوسيدگي ريشه و طوقه سيب , زوال , بيماري زايي , ژن EF-1a , مهاركنندگي رشد ميسليومي , قارچكش
چكيده انگليسي :
Apple (Malus domestica Borkh.) is considered as one of the ten important economic product of the country. Its cultivation is common in the various regions and so far, more than 200 different domestic and foreign apple cultivars is identified which golden and red delicious cultivars are the most important cultivars in terms of cultivated area. Various fungal, bacterial, nematode and viral agents cause weakness and decline of the apple tree and the quantitative and qualitative reduction of the crop. Apple root and crown rot disease, is one of the important diseases of apple trees, due to soil born fungal pathogens, which lead to the decline of apple trees. The disease has a global spread and can occur at all ages of apple production. Previously different Phytophthora and Fusarium species were recognized from the region without molecular identification and climate changes may have effect on fungal balance. Sampling was performed since June to August 2019 from apple orchards with decline symptoms in Semirom and Padena of Isfahan province. Fungal species including Fusarium solani, F. oxysporum, F. equiseti, F. acuminatum and F. redolens were identified. In order to conform morphological identification, Tef1/Tef2 and ITS1/ITS4 primers used in PCR reaction. Amplification of EF-1a gene and ribosomal DNA and sequences analysis showed that the sequence of all identified species, were similar to species in the Gene bank (NCBI). In vitro and in greenhouse pathogenicity test proved the pathogenicity of the identified species. Due to the presence of new fungal agents in apple growing areas of Isfahan, fungicides test performed on F. solani and F. oxysporum species as the most abundant identified species, using fungicides such as Tilt, Eminent, Cabrio duo, Collis, Ortiva Top, Lamardor, Uniform, Flint, Stroby, Roral TS and Topsin M at concentrations of 10, 25, 50, 100 and 200 ppm in vitro based on mycelial growth inhibition assay. The experimental data analysed based on two-factor factorial experiment in a completely randomized statistical design. In general, the results of fungicides test on F. solani showed that Lamardor, Rovral TS and Ortiva Top at concentrations above 10, 25 and 50 ppm, had sufficient mycelial growth inhibition, respectively. Also, the results on F. oxysporum showed that Tilt, Eminent, Ortiva Top, Lamardor and Rovral TS fungicides in concentrations above 10 ppm, had average percentage of mycelial growth inhibition of more than 50%. Fungicide recommendation is not only based on laboratory experiments and it is necessary to be approved in orchard’s condition. It seems that due to climate changes, the balance of fungal species was changed to Fusarium rather than other fungal genera.
Key Words
Apple root and crown rot, decline, pathogenicity, EF-1a gene, fungicide, mycelial growth inhibitor
