Field Resistance to Melon Dieback in Cucumis melo L.

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Cucurbit Genetics Cooperative Report 17:76-77 (article 21) 1994

J. Esteva; F. Nuez
Dpto. Ingenieria Aplicada. Universidad de Murcia. Cartagena (Murcia) SPAIN; Dpto. Biotecnologia. Universidad Politecnica de Valencia. 46022. SPAIN

Melon dieback continues being a serious vine decline disease in melons grown in Spain. The latest reports of CGC (1,2,3) comment on the nature of this disease. In previous experiments, accessions Pat 81 (1) and Acc 6 (3) were those which showed the greatest resistance.

These accessions were evaluated again in field conditions during the spring and summer of 1993. The trials were carried out in two locations (Puzol and Torrepacheco) both on the Spanish Mediterranean coast. The plot on Puzol was the same as that used in the 1992 experiment. Accession VC120, which is very susceptible to melon dieback, was used as a control. In Puzol, the number of replicates per accession was three and the number of plants per replicate was ten. About 500 plants of ‘Rochet’ type melon were also cultivated together with accession Pat 81, VC-120 and Acc 6.

The incidence of disease was nil in Torepacheco. Symptoms of melon dieback were not even observed on the controls. This location is part of the “Campo de Cartagena” region, where the melon dieback attack was in fact very weak during 1993. Nevertheless, the disease was very severe in Puzol, where all controls and “Rochet’ plants died between 18th and 28th July. Some plants of Acc 6 also died during this time. No plants of Pat 81 were affected by the disease (Table 1).

The incidence of melon dieback on Acc 6 was superior to that expected although it did how a certain level of resistance. However, the behavior of Pat 81 clearly differed in relation to the controls. Pat 81 is of asiatic origin. It has been crossed with Spanish cultivars which are susceptible to melon dieback and diverse segregant generations have thus been obtained. These materials could be useful in the genetic analysis of resistance to melon dieback and for the initiation of a breeding programme for resistance to melon dieback.

Table 1. Melon dieback incidence in Puzol.

Replicates

Accession

Incidence*
R-1
R-2
R-3
R-4
R-5
Acc 6 z 10 10 10 10 10
Acc 6 y 3 2 3 1 1
Pat 81 z 6 10 10 10 10
Pat 81 y 0 0 0 0 0
VC-120 z 10 10 10 10 10
VC-120 y 10 10 10 10 10

*z = tested plants; y = affected plants

Literature Cited

  1. Esteva, J., F. Nuez, and J. Garcia-Gimenez. 1992. Search for sources of resistance to a melon dieback in Spain. Cucurbit Gen. Coop. 15:55-56.
  2. Garcia-Gimenez, J., Al Alfar, J. Esteva,, F. Nuez, and M.T. Velazquez.1991. Resistance to Acremonium sp. in Spanish landraces of melon. Cucurbit Gen. Coop. 14:49-50.
  3. Nuez, F. and J. Esteva. 1993. Resistance to melon dieback in Spanish landraces of melon. Cucurbit Gen. Coop. 16:37-38.