Cucurbit Genetics Cooperative Report 14:49-50 (article 17) 1991
J. Garcia-Jimenes, A. Alfaro, J. Esteva, F. Nuez and M. T. Velazquez
Dpto. Produccion Vegetal. Universidad Politecnica de Valencia, Spain (first and second author); Dpto. Biotecnologia, Universidad Politecnica de Valencia, Spain (third and fourth author); Generaltat Valenciana, STT, Moncada, Valencia, Spain (fifth author)
Melon dieback is a new disease that becomes dominant all along the Spanish Mediterranean coast (1). The early symptoms begin to show when fruiting starts:: it is observed a interveinal yellowing on the older leaves. Later these leaves turn flaccid and the end of the shoots wilt. A few days later the plant dies. The causal agent of melon dieback is a fungus which hurts the rootlets since the first stages of plant development. This fungus belongs to genus Acremonium and performs the Koch’s postulates (2).
A technique of artificial inoculation was designed to carry out a fast screening of resistant genotypes to melon dieback: seed were sown into containers filled with vermiculite and germinated in a growth chamber. When the seedlings had a true leaf they were removed from the vermiculite and immediately placed in continuously-aerated nutrient culture solution. Previously it was added a triturated PDA plate where Acremonium had grown at 28 degrees C for 15 to 20 days. Tanks were kept under laboratory conditions. The susceptible genotypes showed root rot within 144 to 240 hr after inoculation and the resistant ones display undamaged roots. A total of 46 Spanish landraces were evaluated by this means (Table 1).
Table 1. Resistance to Acremonium sp. in Spanish landraces of melon.
Landrace |
Rep 1 |
Rep 2 |
| Pat 6 | R/S* | R |
| Pat 13 | R/S | S |
| Pat 22 | R | – |
| Pat 29 | R/S | R |
| Pat 34 | R/S | R/S |
| Pat 35 | R | S |
| Pat 36 | R | – |
| Pat 38 | R | R/S |
| Pat 39 | R | – |
| Pat 42 | R/S | – |
| Pat 46 | R/S | – |
| Remaining landraces | S | – |
*R: No plant showed root rot. S: All of the plants showed root rot. R/S: Doubtful reaction.
A similar disease to melon dieback existed in Spain in the thirties (3 and 4). In any case melon dieback has been known for 20 years although it has begun to be a serious problem in the eighties. The increase of this disease in the last years may have been owed to a rise in inoculum in the soil as a result of a continuous practice of melon cultivation, and to massive substitution of landraces by improved cultivars which are susceptible to melon dieback. The results of the present work seem to suggest that some of old landraces could be resistant.
Literature Cited
- Garcia-Jimenez, J., M. T. Velazquez, and A. Alfaro. 1989. Secuencia de sintomas en el colapso de melon. Boletin de Sanidad Vegetal y Plagas 4: 333-342.
- Garcia-Jimenez, J., M. T. Velazques, and A. Alfaro. 1989. Acremonium sp. agente causal del scolapso del melon en el levante espanol. Documentos de Trabajo del V Congreso Nacional de Fitopatologia. Seccion Etiologia y Epidemiologia (Comunicaciones): 17-18. Badajoz, Spain.
- Gomez-Clemente, F. 1931. Trabajos de la Estacion de Fitopatologia Agricola de Valencia (Burjasot). Boletin de Patologia Vegetal y Entomologia Agricola 5: 162.
- Gomez-Clemente, F. 1932. Trabajos de Estacion de Fitopatologia Agricola de Valencia (Burjaasot). Boletin de Patolgia Vegetal y Entomologia Agricola 6: 193.