Pg. 58-62 Microbial ecology of litchi fruit surfaces

Microbial communities of the phyllosphere are diverse and include bacterial, fungal and yeast genera, which are pathogenic or non-pathogenic to the host plants. Investigating the dynamics between these communities is crucial in understanding the relationship between epiphytic micro-organisms and plant diseases. In view of this, the microbial dynamics of the litchi fruit were studied from flowering till harvest. The study was carried out on cultivar Mauritius in Malelane (2004 and 2005 seasons) and cultivar McLean’s Red in Tzaneen (2005 season). Samples were collected from flowering till harvest from three or four orchards respectively every second week. Total fungal, yeast and bacterial counts were taken of all samples. Results indicate the population density gradually increased from flower bud stage to
full bloom and to the senescence stage. A population density decrease afterwards was shown for both cultivars during both seasons. Although the total Penicillium counts fluctuated between samplings, a relatively higher number was observed between flowering and fruit set and at maturity. This could possibly be attributed to the amount of nutrients released from the flowers and the developing fruit and the change in weather conditions during the seasons.