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Botanical extracts as an alternative crop protection agent: Towards climate smart crop protection

Lerato Matsaunyane: Agricultural Research Council

<div>Pressures introduced to the agricultural sector by climate change include increase in temperature increase in irrigation demand, and increase in crop diseases. Various methods are currently used to bacterial pathogens and these methods have varying degrees of effectiveness. A study was initiated on weed plants as potential crop protection agents will offer safer, effective, inexpensive and biodegradable solution. In the study, the antibacterial properties of extracts prepared from weed plants were investigated against economically important vegetable bacterial pathogens. Previous studies showed that the most common vegetable diseases found by emerging farmers in the Gauteng Province include cabbage soft rot, tomato bacterial speck and spot, bean leaf spot, and potato blackleg and soft rot. Our study selected weeds that were readily accessible to the Gauteng farmers, and these were <em>Lantana camara</em> L. and <em>Melia azedarach</em> L. Antibacterial studies were done against <em>Pectobacterium carotovorum</em> subsp. <em>carotovorum</em> (Pcc), <em>P</em>. <em>carotovorum</em> subsp. <em>brasiliensis</em> (Pcb), <em>Xanthomonas campestris</em> pv. <em>campestris</em> and <em>Burkholderia</em> <em>andropogonis</em>. Results from the minimum inhibitory concentration (MIC) showed that 2.5mg/ml Lantana-and Melia-based extracts inhibited the growth of all selected bacterial pathogens by 100% and 80%, respectively. Evaluation of the mode of bacterial inhibition of the weed extracts, analyzed through microscopy, showed that both extracts caused significant morphological changes to all of the selected bacteria, which was visualized as large outpouching of the bacterial cell wall. The results show that both weed extracts are effective antibacterial agents and have the potential to be used as alternative biological crop protection agents.</div>