ISHS Acta Horticulturae 98: Symposium on Research on Recirculating Water Culture
ROOT DEATH AND ASSOCIATED PROBLEMS |
| Authors: | M. L. Daughtrey, P.A. Schippers |
| Abstract:
In order to test the transmissibility of root death symptoms in an NFT system, symptomatic roots from cucumber or tomato plants were placed within eleven of twelve unconnected NFT systems planted in tomatoes. Only a minority of the inoculations with decaying roots resulted in root death symptoms; in one case, a period of water stress appeared to trigger root death development. Both individual plants of one variety and different varieties appeared to vary in their susceptibility to root death. Various micro-organisms were isolated from diseased roots, but none of these were determined to be the causal agent of root death. Preventive control treatments of 1 and 5 ppm copper sulfate, 69 ppm Lesan and ultraviolet light gave no direct phytotoxic effects; ultraviolet light, however, caused precipitation of iron from chelate, leading to pinkish roots and foliar iron deficiency symptoms. Evaluation of treatment effectiveness was not possible, due to the absence of symptom development in the majority of the untreated inoculated systems. In contrast to the difficulty of transmitting root death of an unknown etiology, transmission of Colletotrichum coccodes infection from diseased eggplant roots to roots of older tomato plants was easily achieved within NFT systems. | |
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