Control of latent infections and postharvest decays by preharvest applications on organic apple

BASSO, CARLA N.; STANGAFERRO, MARÍA; CARRÁ, A; LUTZ, M. C.; SOSA, M.C.; BLACKHALL, VALERIA

PHYTOPATHOLOGY

AMER PHYTOPATHOLOGICAL SOC

Lugar: St. Paul, Minnesota; Año: 2022 vol. 112

0031-949X

Calyx and stem decays originate in the orchard and develop postharvest, resulting in important economic losses in North Patagonia,Argentina. In this study, we determined the effectiveness of pre-harvest applications of three formulations on the incidence of bothlatent infection (LI) and postharvest decay (PD) in apple fruit (cv Atwood) from an organic orchard. Timorex Gold® (tea tree extract;TTE; 1.5 L/ha), Biofruit® (peracetic acid; PAA; 100, 500 and 750 ppm), Raisan® (chitosan; 20 L/ha), or water (control), were sprayed ina commercial orchard 14 d before harvest onto randomly distributed, complete tree rows, with 3 repetitions/treatment. Fruit of thecentral plants (1200 kg/treatment) was harvested and stored at ?1/0°C and 95% RH. At harvest, LI was determined by fruit dissection (n= 60) and pathogen isolation. PD evaluation was carried out in fruit stored for 150 and 180 d (n = 750). In calyx, a 10% LI reductionwas achieved with PAA 750 and 100 for Botrytis cinerea and by PAA 100 and TTE for Fusarium spp. At 150 d of storage, PD byAlternaria was reduced by 50.3% by PAA 100. At 180 d there was no significant difference in PD among treatments and there was nocalyx mold with PAA 750, TTE, and Raisan®. This study indicates that the preharvest application of the above formulations is suitablefor organic production and might reduce the incidence of postharvest diseases in apples. New assays are proposed to assess treatments?efficacy at earlier phenological stages.