Suppression of overwintering Botrytis cinera inoculum on grape rachii using antagonistic fungi : a dissertation in partial fulfilment of the requirements for the Degree of Bachelor of Horticultural Science at Lincoln University

Abstract

Botrytis cinerea is the causal agent of 'Early Botrytis rot' and 'Common Botrytis rot' of grapes. The main objective of this dissertation was to determine whether previously identified fungal antagonists were able to reduce the incidence of overwintering B. cinerea on grape rachii. In two field trials, (Napier, Lincoln) Epicoccum sp. (21) and Ulocladium sp. (13) were applied to grape rachii after harvest and challenged with Botrytis cinerea. Assessments of Botrytis colonisation of grape rachii were made monthly for a period of five months. Results were inconclusive due to low levels of Botrytis in all treatments, a consequence of the warmer and drier weather conditions experienced during the autumn period. Rachii collected from the field trial sites were examined for the presence of dormant Botrytis mycelium or sclerotia. They were surface sterilised prior to plating out on PDA for three weeks. No colonies of B. cinerea were obtained from rachii from either field trial site, indicating that the pathogen was not present in the tissue in a dormant form.