Behaviour of thiabendazole when used as a post-harvest dip in banana packing sheds

Abstract

A series of trials was undertaken to study the behaviour of a thiabendazole wettable powder, when used as a post-harvest treatment for the control of squirter and blackend diseases in bananas packed as 'singles' in wooden boxes. In three grower sheds box lots of 100 were dipped in a range of fungicide concentrations, under conditions that could be expected to differ from those in a centralized packing shed. There was an apparent depletion of thiabendazole, the depletion rate being highest in the initial stages of dipping and after topping, and over all trials each 25 cases treated appeared to reduce concentration by approximately 21 per cent. Topping up appeared to cause a sudden rise in thiabendazole concentration. Fruit skin deposits decreased significantly (P < 0.001 ) as concentration decreased and were 0.8 p.p.m. for a dip at 110 p.p.m. and 1.4 p.p.m, for one at 400 p.p.m. No phytotoxic effects were observed on either green or ripe fruit, and ripening abnormalities were absent. The trials indicated that with an initial concentration of about 200 p.p,m. and using a recommended dip management procedure, a grower should be able to treat 100 boxes in any one lot of dip and effectively control the major post-harvest fruit rots.