Agri Kultuur January / January 2018 - Page 40

Fungicides from the soil Karen du Plessis Bacillus micro-organisms living in the very soil where crops are grown were put to the test and proofed to produce ingenious weapons for the effective control of diseases and mould on fruit. T he perishable produce industry experiences considerable post-harvest crop losses every year. It is estimated that between 25% and 40% of the fruit and vegetables harvested worldwide are lost to post-harvest diseases. Much of this is due to decay caused by microorganisms (fungal, bacterial and viral phytopathogens) that produce diseases that occur during the transport, storage and sale of fresh produce. fungicides having been deregistered, certain pathogenic strains have developed resistance to the fungicides. Internationally, consumers are demanding that natural alternative control methods be found. Synthetic chemical fungicides that control post-harvest disease are increasingly associated with adverse environmental impacts and health issues, and are therefore falling out of favour due to the chemical residues they leave behind in the food chain. Unlocking potential In a previous Hortgro Science and PHI Programme-funded research project, Prof. Kim Clarke, from the Department of Process Engineering at Stellenbosch University, identified the potential value of the metabolic bioproducts of Bacillus amylolique faciens to be a green fungicide against Botrytis cinerea in table grapes. She found that her chosen biocandidate acts as a natural microscopic factory of lipopeptides that demonstrate the ability to act as fungicides across a broad spectrum. She furthermore established that the bioproducts, even in crude, unpurified form, are effective in any physical and chemical environment. In addition to some of the most effective Prof. Kim Clarke, project leader. The search for innovative and acceptable controls has led the agricultural sector to green chemistry as a way to manage and eliminate fungal and bacterial post-harvest diseases. Building on her previous work, Prof. Clarke designed a follow-up project focusing on pathogens that eat away at the profits of stone fruit producers. To upscale the production process from shake flask (500ml) to the level of a bioreactor with a capacity of two litres, is a necessary task. AgriKultuur |AgriCulture 40