Identification and characterization of Diplodia mutila, D. seriata, Phacidiopycnis washingtonensis and Phacidium lacerum obtained from apple (Malus x domestica) fruit rot in Maule Region, Chile

Abstract

Two members of the family Botryosphaeriaceae (Diplodia mutila and D. seriata), one member of the family Bulgariaceae (Phacidiopycnis washingtonensis) and one member of the family Phacidiaceae (Phacidium lacerum) have been described as fungal plant pathogens causing apple rot during preharvest and/or postharvest. During a survey of apple rot in the commercial orchard cvs. Cripps Pink, Fuji and Gala that was conducted in the 2014–2015 and 2015–2016 seasons in the Maule Region, Chile, 820 isolates were obtained from 880 apple rot samples. Phylogenetic analyses of the internal transcribed spacer (ITS) region, portion of the β-tubulin gene (BT), large ribosomal subunit (LSU) region and small ribosomal subunit (SSU) region identified Diplodia mutila, D. seriata, Phacidiopycnis washingtonensis and Phacidium lacerum. Morphological features of isolates of D. mutila, D. seriata, Pha. washingtonensis and P. lacerum were similar to those described in the literature for the respective species. The isolates of D. mutila, D. seriata, Pha. washingtonensis and P. lacerum were sensitive to fludioxonil, pyrimethanil, tebuconazole and thiabendazole fungicides. The significant largest lesion on apple fruits cv. Cripps Pink were developed, when the fruits were inoculated from 15 days before harvest with Pha. washingtonensis while for D. mutila, D. seriata, P. lacerum was the same day of harvest. The fungal species Pha. washingtonensis and P. lacerum were the most important in developing apple rot (lesions) during cold storage. The specie D. seriata was the most predominant fungus obtained from apple fruit rot in the Maule Region, Chile. This study gives a better insight to the fungal species causing apple fruit rot in the Maule Region, Chile.