Evolution of Muskmelon Virus Infection on Field Crops in the Ebro Valley (Spain).

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Cucurbit Genetics Cooperative Report 13:20-24 (article 8) 1990

M. Luis Arteaga and J. Alvarez
Servicio de Investigación Agraria, Apartado 727, 50080 Zaragoza, SPAIN

About 15 different viruses have been reported infecting muskmelon (6). Mainly 10 of those viruses have some economic incidence (5), and among those five have been reported in Spain: Cucumber mosaic virus (CMV), watermelon mosaic virus-2 (WMV-2), squash mosaic virus (SqMV), muskmelon necrotic spot virus (MNSV), and Zucchini yellow mosaic virus (ZYMV) (1,2,3,7,8).

In 1984 a study aimed to assess the importance, identity, and evolution of virus infection on open-field grown muskmelon was started in experimental plots located in the Central Ebro Valley (Spain).

A total number of 633, 574, 590 and 125 plants from different local cultivars were examined during 1985, 86, 87 and 88, respectively.

Plants were sown in pots and transplanted to the field when the seedlings reached the 2-3 leaf stage (3rd June 1985, 28th May 1986, 1st June 1987, and 24th May 1988). All plants were individually observed at least once a week and the presence of foliar virus symptoms was recorded. For virus identification some samples were taken, at random, from plants that showed virus like symptoms; in this way 81, 75, 50 and 49 samples were studied in 1985, 86, 87 and 88, respectively.

Virus identification was done through biological (9) and serological (4) tests. The serological tests were done with CMV, WMV-2, ZYMV and PRSV-w antisera from INRA, Montfavet (France).

Virus symptoms were first observed as foliar mosaics 17 days after transplant in 1985, 18 days in 1986, 24 in 1987, and 28 in1988. Virus infection reached 100% of the plants 70, 66, and 49 days after transplant in 1986, 87, and 88, respectively (Fig. 1). In 1985 the infection had reached 95% of the plants 71 days after transplant, but an important powdery mildew infestation made difficult further observations.

The reactions of the diagnostic species and the serological tests showed that CMV and WMV-2 were the most improtant, and practically the only viruses present during 1985, 86, and 87. MNSV appeared in a few plants in 1986 (Table 1).

In 1985 both viruses (CMV and WMV-2) appeared simultaneously, but later WMV-2 became the most frequent (Fig. 2A). However, in 1986 CMV appeared first and was much more frequent than WMV-2 (Fig. 2B). In 1987 both viruses appeared almost simultaneously and none of them was clearly more frequent than the other (Fig. 2C).

In 1988 symptoms differed from those observed in previous years. Plants started showing vein clearing followed by leaf decoloration, yellowing, and sometimes necrotic spots on leaves and stems, and death of some of the plants. Plant growth became highly affected, and many flowers aborted before anthesis. Delays in fruit set and development were also observed, most of the fruits showed deformations and/or star-shaped cracking similar to those observed by other authors in ZYMV natural infections (4,10).

From 17 samples taken from 21st June, when the first symptoms were observed, until 20th July, only ZYMV was found. CMV was detected later, but always mixed with ZYMV. From samples taken from 14th September, on the same plants that the above ones, a mixed infection of CMV and ZYMV was found, and in three plants WMV-2 was also found.

Varietal differences were observed in plant mortality and flower abortion during 1988 (Table 2), that could be attributed to vigor differences between cultivars or to varietal differences in the reaction to the virus (4).

Causes of this sudden upright of ZYMV incidence in the area are unknown but most probably they are related with an unusual mild spring and summer during 1988. A rainy autumn and mild temperatures during winter and spring could hasten weed development, that acted as virus source, and presence of high aphid populations during transplant and first stages of plant development. At the same time muskmelon plants grew weaker and slower that under normal climatic conditions.

Analysis of variance were performed after angular transformation of data. Mean comparisons were done according to Duncan’s multiple range test (p  0.05).

Table 1. Viruses detected and their frequency (%) in muskmelon foliar samples in 1985, 1986 and 1987.

Year

Number of
Samples

VIRUSES
 
CMV
WMV-2
CMV+WMV-2
MNSV
CMV+MNSV
1985 81 17 72 11
1986 75 48 5.3 42.7 2,7 1,3
1987 50 24 40 36

Table 2. Average percentage of surviving and pistillate flower producing plants.

CULTIVAR

% of surviving plants

% of plants producing pistillate flowers
Ariso 72 ab 26.6 a
Tendral Verde 60 a 64.0 b
Rochet 76 ab 71.3 bc
Piel de Sapo 92 b 55.0 b
Negro 96 b 92.0 c

Figure 1. Virus infection evolution on open-field muskmelon grown during 1985, 1986, 1987 and 1988.
Figure 2. Evolution on CMV and WMV-2 infection on open-field muskmelon grown in 1985 (A), 1986 (B) and 1987 (C).

figure 1 and figure 2

 

Literature Cited

  1. Cuadrado Gómez, I. and Z. P. Moreno Gómez. 1987. Detection of viruses by dot-inmunobinding assay in cucurbit plants grown under plastic cover in Almeria (Spain). Proc. VIIth Med. Phytopathol. Union, Granada:158.
  2. Diaz, Múgica, M. V. and J. R. Diaz Ruiz. 1987. Squash mosaic virus isolated from melons in Spain. Proc. VIIth Congress Med. Phytopathol. Union, Granada:142.
  3. Garcia Luque, I., J. R. Diaz Ruiz, M. Rubio Huertos, J. M. Kaper. 1983. Cucumovirus survey in Spanish economically important crops. Phytopathol. medit., 22:127-132.
  4. Lecoq, H., M. Pitrat, M. Clement. 1981. Identification et caractérization d’un potyvirus provocant la maladie du rabougrisement jaune du melon. Agronomie, 1:827-834.
  5. Lecoq, H. 1985. La protection phytosanitaire. III Les viroses. In melon. Marché et techniques de production. Ctifl:210-213.
  6. Lovisolo, O. 1981. Virus and viroid diseases of Cucurbits. Acta Horticulturae, 127:175-182.
  7. Luis Arteaga, M. 1989. Detección del virus del mosaico amarillo del calabacín en cultivos de Cucurbitáceas en España. Investigación Agraria, (In press).
  8. Luis Arteaga, M. and J. Alvarez. 1986. Comportamiento del melón frente a virus en condiciones naturales de infección en Zaragoza. II Congreso Nacional S.E.C.H. Vol. II:1037-1048.
  9. Marrou, J. 1967. Amélioration des méthodes de transmission mécanique des virus par adsortion des inhibiteurs d’infection sur le charbon végétal. C.R. Acad. Agric. France, 53:972-981.
  10. Nameth, S. T., J. A. Dodds, A. O. Paulus, and A. Kishaba. 1985. Zucchini yellow mosaic virus associated with severe diseases of melon and watermelon in Southern California desert valleys. Plant Disease, 69:785-788.