A research team has studied the residue persistence of fungicides, commonly used in vineyard to reduce the attack from Botrytis cinerea, during the cold storage of ‘Thompson Seedless’ table grape stemmed berries.For the study, the berries were stored at 1) atmosphere of air or 2) 0.3 µL/L ozone enriched air.
The berries were treated with the following fungicides: Boscalid, Iprodione, Fenhexamid, Cyprodinil, Pyrimethanil.
After fungicide treatment, the berries were dried in air for 24 h, packaged in plastic clamshell boxes and stored at 2°C and 95% RU for 36 days. The amount of residues was measured at the beginning of storage and at 12-day intervals.
Results showed that the residues of Boscalid, Iprodione, Fenhexamid and Pyrimethanil declined during storage in air, while those of Cyprodinil did not significantly change during 36-day storage.
The storage in ozone accelerated markedly the decline rate of Fenhexamid, Cyprodinil and Pyrimethanil, but it did not affect Boscalid and Iprodione decline. At the end of storage, the decline rate of Fenhexamid, Cyprodinil and Pyrimethanil was 1.6-, 2.8- and 3.6-fold higher, respectively, in berries stored in ozone than in those stored in air.
Despite the structural similarity among these fungicides, the Pyrimethanil declined more rapidly than Cyprodinil in presence of ozone, while Fenhexamid declined more rapidly than Cyprodinil and Pyrimethanil with or without ozone. After 36-day storage, only 59.2% and 35.5% of the initial value of residues remained on berries stored in air and in ozone, respectively.
The authors conclude indicating the possibility to use ozone during storage not only as mean to control fungal decay but also as a solution to reduce fungicide residues on table grapes. However, the same authors suggest that toxicology studies should be carried out to consider the possible human health risks of the breakdown products of fungicides after gaseous ozone treatment.
Source: Karaca H., Walse S.S., Smilanick J.L., ‘Effect of continuous 0.3 µL/L gaseous ozone exposure on fungicide residues on table grape berries’, Postharvest Biology and Technology, 2012, Issue No. 64, pagg. 154-159. http://www.sciencedirect.com/science/article/pii/S0925521411001700