Effect of placing paper sleeves over Tommy Atkins, Kent or Keitt mangoes, prior to harvest, on disease incidence and fruit physico-chemical characteristics after extended cold-storage.
Oosthuyse S. A.
Author Affiliation: HortResearch SA, PO Box 3849, Tzaneen 0850, South Africa.
27 : 75-79
Abstract : In an experiment conducted in South Africa during 2006-07, fruits of mango cultivars Tommy Atkins, Kent and Keitt were covered with durable, coated paper sleeves as a non-chemical means of controlling anthracnose (Colletotrichum gloeosporioides [Glomerella cingulata]) and soft-brown rot (Botryodiplodia theobromae) diseases resulting from pre-harvest infections that manifest themselves after harvesting. Comparison was made with the commercially adopted chemical fruit treatment of monthly copper oxychloride spraying and postharvest prochloraz dipping (carried out after postharvest hydro-heating). Sleeving was carried out during late October and November 2006 prior to and after the occurrence of rain. The fruits were subjected to hydro-heating after harvesting, cold storage at 11°C for 28 days, and subsequent storage at 20°C to allow further ripening. The control fruits were sprayed with copper oxychloride from the date of first sleeving and dipped in prochloraz for 20 seconds after hydro-heating. Sleeving in late October and early November prior to the commencement of rain was as effective in reducing the incidence of anthracnose as the commercial treatment. Later sleeving was less effective due presumably to infections occurring during or shortly after rain. The incidence of soft brown rot was low. Differences among the treatments were not clear in Tommy Atkins or Kent. In Keitt, the incidence of soft brown rot was greater in fruits sleeved after the occurrence of rain. Differences in soft brown rot incidence between fruits sleeved earlier and chemically treated fruits were not apparent. In general, ground skin colouration was markedly enhanced, although slightly, as a result of sleeving in late October. Fruit blush cover was not affected by sleeving. However, the intensity of blush colouration was visibly reduced when sleeving was carried out in late October. Sleeving had no significant effect on lenticel damage cover, juice total soluble solids content, taste appeal, or pulp colouration. Solar injury did not occur in sleeved fruits, such injury having affected 11% to the non-sleeved Keitt fruits. It was concluded that for sleeving to be a feasible commercial fruit protection alternative, it requires adoption in small-tree orchards, where fruits are easily accessible to workers without the extensive use of ladders.