Browsing by Author "De Kock, P. J."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- ItemApplication of fungicides against postharvest botrytis bunch rot of table grapes in the Western Cape(South African Society for Enology and Viticulture, 1994) De Kock, P. J.; Holz, G.Fungicide programmes for the control of postharvest Botrytis bunch rot on table grapes were evaluated in six trials from 1984/85 to 1991/92 in the Western Cape. The study demonstrated the ineffectiveness of dicarboximide applications during bloom to early pea size in well managed vineyards. Dicarboximides were most effective when applied from bunch closure to ripening. lprodioue/sulphur treatments at veraison and before harvest reduced Botrytis bunch rot, but they were ineffective in inhibiting infection during storage. Control was only achieved when grapes were exposed to S02 during storage. Although bunch dip treatments reduced infection in the vineyard, this control was not commercially acceptable. Therefore no real advantage was found when bunches were dipped in fungicide at veraison to ensure better coverage. The fact that berries became infected primarily during harvest, package operations and storage, emphasised the necessity for reducing B. cinerea inoculum on harvested grapes. It is suggested that the results of this investigation may lay the foundation for incorporating biological control in Botrytis bunch rot control.
- ItemUse of gamma irradiation for control of postharvest botrytis cinerea bunch rot of table grapes in cold storage(South African Society for Enology and Viticulture, 1991) De Kock, P. J.; Holz, G.The feasibility of employing gamma irradiation for the control of postharvest Botrytis bunch rot of table grapes in cold storage was studied. Table grape cultivars from commercial vineyards in the Paarl and Hex River Valley areas were packed as for export in vented corrugated cartons. The cartons were irradiated at O; 1,5; 2,0 or 3,0 kGy. After irradiation, grapes were kept for 4 weeks at -0,5°C, followed by another week at 10°C. Less decay was observed when table grapes were irradiated soon after packing than after a storage period. Irradiation at 1,5; 2,0 and 3,0 kGy reduced the effect of Botrytis cinerea on Barlinka grapes stored without sulphur dioxide. Irradiation of Waltham Cross and Barlinka grapes at a dose of 2,0 kGy, combined with reduced S02 treatments, resulted in similar control as with the standard practice of enclosing an S02 generator. Browning of Waltham Cross berries and bacterial and yeast growth occurred on the surface of berries irradiated at a dose of 3,0 kGy. Irradiation had no adverse effect on other aspects of quality.