An investigation into the status and control of mango blossom malformation in South Africa.
Schoeman M. H., Botha F. A.
Author Affiliation: Agricultural Research Council, Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit, 1200, South Africa.
: 223-228
Abstract : Mango blossom malformation (MM) is a serious disease in the Republic of South Africa (RSA), causing severe economic losses annually. Current recommendations are to break out the malformed inflorescences as well as three additional nodes of the branch when malformed flowers are clearly visible, but before sporulation occurs. Despite these recommendations, a high incidence of MM was reported during the past two seasons. The aim of this study was to investigate and evaluate the influence of various management practices by producers on the incidence of malformation, and to develop an integrated strategy for optimum control. In the Hoedspruit (Limpopo province) production area, the incidence of MM was monitored on different cultivars at four producer sites. In the Nelspruit (Mpumalanga province) production area, in a 36 year old 'Sensation' orchard, the effect of inflorescence removal combined with chemical control was investigated. Malformed branches were removed at 300-500 mm distance behind malformed blossoms during November. After harvest three treatments were applied, (1) a control treatment (no further removal of malformed branches), (2) further removal of malformed branches, and (3) further removal of malformed branches followed by a spray of benomyl WP at 0.75 g/L. At all sites the number of healthy and malformed inflorescences was counted before inflorescences were removed. Records of all husbandry practices were kept. In the Hoedspruit area removal of the malformed inflorescences led to a 44.3-80.2% decrease in the prevalence of malformation. It was established that branches were not always broken out by producers according to recommendations, leading to poor control of malformation in certain instances. Results of the incidence of malformation at each of the trial sites are presented. The study will continue for a further two years and the results will be used to develop a strategy to minimize mango malformation in South Africa.