ISHS Acta Horticulturae 133: Nutrient Film Technique and Substrates, XXI IHC
THE INFLUENCE OF SOME FACTORS ON THE SEVERITY OF PYTHIUM ROOT ROT OF LETTUCE IN SOILLESS (HYDROPONIC) GROWING SYSTEMS |
| Authors: | D. Funck-Jensen, J. Hockenhull |
| Keywords: | Damping-off, hydroponics, lettuce, nutrient film technique (NFT), Pythium, root pathogen, saprophyte, soilless culture, zoospore |
| Abstract:
Pythium root rot of lettuce cv. 'Ostinata' was investigated in two hydroponic growing systems - nutrient film (NFT) and a container system. Two pathogenic isolates, Pythium ultimum and Pythium type 'F', were used in inoculation experiments. Disease incidence in NFT was generally low, while in the container system disease severity was considerably higher. In the NFT system, symptoms occurred mainly on the roots under the Grodan blocks and along the sides of the gullies where many fine roots were matted together. Pythium could be isolated from the roots of plants growing in inoculated NFT systems during the entire 24 day period of the experiments. Pythium was also isolated from the nutrient solution. The pathogen was frequently isolated from healthy looking roots. The results suggest that Pythium is capable of saprophytic growth and ubiquitous survival in hydroponic systems of the NFT type. Results from experiments with light intensity, heat stress and physical damaging of the roots also support the conclusion that, when lettuce is grown under good conditions in NFT, it appears to be highly resistant to attack from Pythium spp. | |
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