MBOMBELA – The South African Macadamia Growers Association recently held a successful research symposium in Mbombela.
Various topics from the selection of new cultivars to the integrated management were discussed by 17 speakers. One of the topics the more than 250 delegates found interesting was a study on a possible solution to the nut-borer problem.
Willem Steyn’s survey on this topic started in the north eastern parts of SA. He researched the role of entomopathohenic nematodes (EPN) for control of the nut-borer complex. Steyn is a researcher at the Agricultural Research Council’s Institute for Tropical and Subtropical Crops (ARC-ITSC).
He found six local isolates during his survey, of which three showed promising results for use in the future.
The problem of husk rot was discussed by Marieta Schoeman of the ARC-ITSC. She pointed out that husk rot was more prevalent the last few seasons. Preliminary studies show that at least two Diaporthe species were the culprits.
“The macadamia industry is expanding rapidly and the economic impact of husk rot is also increasing,” said Schoeman.
She also did an evaluation of fungicide for controlling husk rot. It was found that it is best controlled with Amistar Top 500ml and Amistar Top applied early.
Lindi Botha, a private researcher from Pretoria, proved that the two-spotted stinkbug can be reared in captivity. Interesting observations that can be applied outside the laboratory were made by such keeping of the insects.
In the light of her findings, she advised farmers to lower their tree heights, scout for the insects in winter and to use insecticide spray before the trees carry blooms.
When it comes to the use of pesticides in macadamia farming, Dr Gerhard Verdoorn from the Griffon Poison Information Centre, pointed out that it is important not to market, sell or spray products that are not registered in South Africa.
“Products that are not registered on macadamia for the specific target at any rate or method should not be used,” explained Verdoorn.
Stephan Schoeman from Envista Horticulture and Research discussed the breaking of surface crusts in macadamia orchards. He came to the conclusion that this damage to orchard crusts can be managed but treatments should not be once-off. A range of tools can be used like gypsum, mulching and compost and soil conditioners.
De Villiers Fourie from the department of zoology and entomology, University of the Free State, investigated the possibility of the two-spotted stinkbug becoming resistant to pyrethroid.
He came to the conclusion that growers should be assisted in the management of pesticide resistance as there is concrete evidence thereof.
He highlighted the need for alternative management methods and research into other active ingredients.
Alex Whyte, sales and marketing manager of Green Farms Nut Factory, gave an overview of the demands of consumers and highlighted the need for healthy options on their menus.
“There is a long-term fundamental shift in the market towards a good kind of fat,” said Whyte.
In future more time should be spent in marketing macadamias as an ingredient in manufactured foods like biscuits and sweets. This highlights a need for the industry to be more cautious than ever when it comes to food safety.”
