Characterization of the host range and sensitivity to fungicides of Trichothecium spp. associated with fruit rot in the field and in storage

During 2017-2019, we observed Trichothecium spp. causing fruit rot in the field and in storage. This study was conducted to examine morphological differences of the species from different hosts, reveal the species' potential host range, and evaluate the efficacy of five fungicides. Six strains of Trichothecium spp. isolated from nectarine, peach and walnut were selected. Although the colony morphology, mycelial growth rate and spore size differed among hosts, phylogenetic analysis based on the internal transcribed spacer and part of the 5MODIFIER LETTER PRIME end of the beta-tubulin gene showed that all tested strains belonged to Trichothecium roseum. For its host range, 23 kinds of fruit were examined using T. roseum strain YT-1 as an inoculum; 10 kinds of fruit, including pear, apple, mango, Chinese chestnut, pepino melon, fig and durian, were susceptible to T. roseum, with minimum inoculation concentrations ranging from 10(4) to 10(5) spores/ml. The fungicides that most effectively inhibited the six isolates were fluazinam and fludioxonil, with EC50 values of 0.07-0.1 and 0.01-0.04 mu g/ml, respectively, followed by difenoconazole (0.81-2.96 mu g/ml), boscalid (5.43-13.51 mu g/ml) and azoxystrobin (9.18-27.25 mu g/ml). Improvement of the shelf life of nectarines held in plastic trays was explored using allyl isothiocyanate (AITC) against T. roseum YT-1. The application of 10 mu l/L AITC significantly suppressed disease symptoms. The findings provide useful information for future disease emergency management in the field and for food preservation.