Lettuce and tomato field trials were performed in an unheated polytunnel in Aberdeenshire to investigate the efficacy and mode of activity of <i>Brevibacillus brevis</i> against grey mould disease (<i>Botrytis cinerea</i>). This was achieved by means of treating plants with whole cultures of <i>B. brevis</i> WT (containing gramicidin S and biosurfactant) and <i>B. brevis</i> E1 (containing biosurfactant only) and also with supernatant and spore fractions of such cultures so that the effects of treatments containing one, both or neither of the potentially active components, gramicidin S (bound to the bacterial spore) and biosurfactant (released into the culture medium) could be assessed. In winter lettuce, WT and E1 reduced grey mould by up to 79% (p=0.05) with no significant disease (p=0.05) between efficacy of these treatments. WT reduced disease by 59% in spring lettuce but at low significance (p=0.2) although marketable yields were significantly improved (p=0.05). The biocontrol treatments WT, E1, SWT and SE1 reduced (p=0.05) grey mould by up to 48% in tomato leaves and 73% of WT treated plants had no stem lesions, significantly more (p=0.05) than lesion-free control plants (17%). These results suggest that both the biosurfactant and gramicidin S play a role in disease reduction. The biosurfactant appears to be responsible for disease reduction on aerial plant surfaces with large surface areas whilst Gramicidin S reduces disease in regions of higher humidity, such as the base of lettuce plants and on tomato stems.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:288359 |
| Date | January 2003 |
| Creators | McHugh, Rosalind Clare |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0022 seconds