Identification and pathogenicity of Phytophthora species in pear commercial orchards in Argentina

SANCHEZ, AIXA DAIHANA; SOSA, MARIA CRISTINA; LUTZ, MARIA CECILIA; CARREÑO, G.; OUSSET, MARIA JULIA; LUCERO, G.

EUROPEAN JOURNAL OF PLANT PATHOLOGY

SPRINGER

Lugar: Berlin; Año: 2019

0929-1873

Bartlett pear cultivar accounts for 40%of the pear production area of Río Negro andNeuquén provinces, Argentina. During fall andspring 2014?2016, symptoms associated withPhytophthora rots were observed in declining commercialorchards. The aims of this survey were: (i) to identifythe Phytophthora species associated with these irrigatedcommercial orchards, using different isolationstrategies; and (ii) to investigate the pathogenic potentialof Phytophthora isolates on pear fruit and tree. Severalstrategies were used to isolate Phytophthora spp. fromsoil/roots and collar rot. Fifty-two isolates were groupedby morphological and cultural characters, correspondingmainly to P. cactorum and other species of Clade 6.P. cactorum was the main species obtained from collarwood and root/soil by fruit bating. The identity of thespecies was confirmed by sequencing of the internaltranscriber spacers (ITS, ITS1, and ITS4 primers) andcomparison with sequences available in GenBank andPhytophthora Database (http://phytophthoradb.org).Sequences of P. inundata, P. rosacearum, P. lacustris,P. termophila and P.cactorum were deposited inGenBank. Pathogenicity tests were made for eachspecies on 1-year-old shoots and fruit of Bartlett andd?Anjou cultivars, and then on 2-year-old rootstockroots of Bartlett cultivar. All Phytophthora specieswere pathogenic, with different levels of severity amongisolates. P. cactorum was the most aggressive species onpear rootstock roots and 1-year-old shoots.