Articles
Variability of postharvest pyrimethanil effects on decay during and after storage of ‘Fuji’ apple
Article number
1451_19
Pages
133 – 140
Language
English
Abstract
This study evaluated the effects of postharvest fumigation of the fungicide pyrimethanil (9.6 g a.i. t‑1) on apple fruit decay.
Four experiments were performed under large-scale commercial storage conditions using ‘Fuji’ apples grown in southern Brazil.
In experiments 1 and 2 (Vacaria region), fruit classified as early and advanced maturity at harvest were stored in a controlled atmosphere (CA, 1.2 kPa O2<0.5 kPa CO2, 0.8°C) for 240 d.
In experiments 3 (São Joaquim region) and 4 (Fraiburgo region), the fruit were stored in CA for 150 d and in the air for 105 d, respectively, at 0.8°C. In each experiment, fruit samples from 3 to 10 orchard plots were collected from bins of commercially harvested fruit.
Ten fruit samples of ≈400 kg each (bins) were used for fruit assessment after storage for each orchard plot.
Within 7 d after harvest, half of the samples from each orchard plot (n=5 bins) were treated with pyrimethanil in commercial storage facilities using thermal fogging (ActiMist™) for 24 h.
After storage, fruits were assessed for the incidence of each rot symptom, caused by each pathogen (day 0). A subsample of 100 decay-free apples was then selected from each sample and held at 22°C for a 7-day shelf life assessment (day 7). Fungicide treatment reduced the total incidence of rots (sum of incidences of all rot symptoms) in all experiments.
The average total incidence of storage rots ranged from 2.5 to 12.9% for fungicide treated and 4.5-18.7% for control fruit at day 0. In contrast, in the day 7 shelf life assessment, total incidence of rots increased to 5.8-16% for fungicide treated and 19.5-38% for control fruit.
Bull’s-eye was the main rot symptom followed by blue mold, gray mold, and moldy core rot after cold storage, with blue mold dominating rots, followed by Bull’s-eye rot, gray mold, and moldy core rot at the day 7 assessment.
The contrast in total incidence of rots between control and fungicide ranged from 2.0 to 5.8% after storage and 13.7 to 21.8% after shelf life, depending on the experiment.
Blue mold and bull’s eye rot were the predominant rot symptoms and the most affected by the pyrimethanil.
The incidence of bitter rot varied from 0.0 to 4.4% depending on the experiment and was unaffected by pyrimethanil.
Similarly, the incidences of Alternaria rot, white rot, and Rhizopus rot were consistently low (≤1%) and also unaffected by the fungicide treatment.
The results reinforce that region and orchard are major sources of variation in postharvest storage rot incidence.
Development of decay symptoms during a short, ambient temperature incubation following long-term cold storage is greater than rot development during the long-term cold storage period.
Four experiments were performed under large-scale commercial storage conditions using ‘Fuji’ apples grown in southern Brazil.
In experiments 1 and 2 (Vacaria region), fruit classified as early and advanced maturity at harvest were stored in a controlled atmosphere (CA, 1.2 kPa O2<0.5 kPa CO2, 0.8°C) for 240 d.
In experiments 3 (São Joaquim region) and 4 (Fraiburgo region), the fruit were stored in CA for 150 d and in the air for 105 d, respectively, at 0.8°C. In each experiment, fruit samples from 3 to 10 orchard plots were collected from bins of commercially harvested fruit.
Ten fruit samples of ≈400 kg each (bins) were used for fruit assessment after storage for each orchard plot.
Within 7 d after harvest, half of the samples from each orchard plot (n=5 bins) were treated with pyrimethanil in commercial storage facilities using thermal fogging (ActiMist™) for 24 h.
After storage, fruits were assessed for the incidence of each rot symptom, caused by each pathogen (day 0). A subsample of 100 decay-free apples was then selected from each sample and held at 22°C for a 7-day shelf life assessment (day 7). Fungicide treatment reduced the total incidence of rots (sum of incidences of all rot symptoms) in all experiments.
The average total incidence of storage rots ranged from 2.5 to 12.9% for fungicide treated and 4.5-18.7% for control fruit at day 0. In contrast, in the day 7 shelf life assessment, total incidence of rots increased to 5.8-16% for fungicide treated and 19.5-38% for control fruit.
Bull’s-eye was the main rot symptom followed by blue mold, gray mold, and moldy core rot after cold storage, with blue mold dominating rots, followed by Bull’s-eye rot, gray mold, and moldy core rot at the day 7 assessment.
The contrast in total incidence of rots between control and fungicide ranged from 2.0 to 5.8% after storage and 13.7 to 21.8% after shelf life, depending on the experiment.
Blue mold and bull’s eye rot were the predominant rot symptoms and the most affected by the pyrimethanil.
The incidence of bitter rot varied from 0.0 to 4.4% depending on the experiment and was unaffected by pyrimethanil.
Similarly, the incidences of Alternaria rot, white rot, and Rhizopus rot were consistently low (≤1%) and also unaffected by the fungicide treatment.
The results reinforce that region and orchard are major sources of variation in postharvest storage rot incidence.
Development of decay symptoms during a short, ambient temperature incubation following long-term cold storage is greater than rot development during the long-term cold storage period.
Authors
L.C. Argenta, F. Büchele, C. Ogoshi, M.J. Vieira, J. Alves, C.N. Nesi, D.A. Neuwald
Keywords
Malus domestica Borkh., postharvest diseases, fungicide, fruit rot
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