ISHS Acta Horticulturae 216: III International Symposium on Carnation Culture
POSSIBILITIES OF CROSS-PROTECTION AGAINST FUSARIUM WILT BY NON-PATHOGENIC ISOLATES OF FUSARIUM F.SP. DIANTHI |
| Author: | H. Rattink |
| Abstract:
Pre-inoculation of plants of a susceptible carnation cultivar with a less or non-pathogenic isolate of Fusarium oxysporum f.sp. dianthi prior to inoculation with a pathogenic isolate diminished the number of diseased plants, proportional to the level of pathogenicity of the isolates used for pre-inoculation. No effect was observed after pre-inoculation with isolates of formae speciales of F. oxysporum from other floricultural crops. The intensity of the effects depended on the period between pre-inoculation with the non-pathogenic isolates and the inoculation with the pathogenic isolate and on the concentration of both the non-pathogenic and pathogenic isolates. The best effects were seen when the time interval was c. 7 days. Pre-inoculation with a suspension of spores of 106 spores per ml was more effective then with a suspension of 103 spores per ml. After inoculation with a suspension of 103 spores per ml of the pathogenic isolate fewer plants were attacked than after inoculation with a suspension of 106 spores per ml. After one year, disease percentages were 15–30 compared to 100 in the non pre-inoculated treatment after a half year. Experiments on rooting cuttings in a substrate, to which spores of non-pathogenic isolates of F. oxysporum f.sp. dianthi were added, were not succesfull. No roots were formed. Only when the medium was drenched with a solution of spores one week after the start of the rooting period cuttings with a normal root system were obtained. The non-pathogenic F. oxysporum could be isolated from the plants. The pre-treated rooted cuttings were planted in lightly contaminated soil or in steamed soil, which was inoculated later, after different intervals, with a pathogenic isolate of F. oxysporum f. sp. dianthi. The pre-treated plants were attacked at a later stage and to a lesser extent than non pre-treated plants. The results of the experiments indicate a process of cross-protection. More research however has to be done to incorporate this process of partial control into the whole complex of Fusarium wilt control. | |
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