January 23, 2003
From: American Phytopathological Society, Plant Disease Notes [edited]

Pumpkin (Cucurbita maxima and C. pepo), a new host of Beet pseudo yellows virus in California
W. M. Wintermantel, USDA-ARS, 1636 E. Alisal Street, Salinas, CA 93905. Plant Dis. 88:82, 2004; published on-line as D-2003-1031-02N, 2004. Accepted for publication 3 Oct 2003.

In the summer of 2002, pumpkin plants (_Cucurbita pepo_ L. and _C. maxima_ Duchesne) with extensive leaf chlorosis similar to those observed in crinivirus infections were found in fields at 2 locations in Monterey
County, California. Leaves of diseased plants were observed to have large populations of the greenhouse whitefly (_Trialeurodes vaporariorum_) present.

Double-stranded RNA was extracted from symptomatic leaves of these plants and tested by northern hybridization for numerous criniviruses. A positive signal was identified exclusively with probes against the HSP70h gene of Beet pseudo yellows virus (BPYV) and confirmed by reverse transcription-polymerase chain reaction (RT-PCR) amplification of a 335-nucleotide section of the BPYV minor coat protein (CPm) gene (3).

Similar symptoms were observed in additional fields in 2003, and BPYV was again confirmed. In addition, the CPm RT-PCR product was cloned into a TOPO pCR2 vector (Invitrogen, Carlsbad, CA) and sequenced. BLAST analysis of the cloned CPm RT-PCR product sequence corresponded to the published sequence of the CPm gene of BPYV (98 percent) (3) and Cucumber yellows virus (CuYV), a recently sequenced crinivirus considered to be a strain of BPYV (97 percent) (2).

Incidence of BPYV in pumpkin appears to be variable and probably corresponds to the incidence of viruliferous whiteflies. On the basis of foliar symptoms, BPYV incidence varied from less than 50 percent in these fields in 2002 to nearly 100 percent infection of a large commercial field in 2003. BPYV is transmitted semipersistently by the greenhouse whitefly and has an extensive host range (1).

The virus causes economic losses worldwide for greenhouse vegetable production and is becoming an increasing problem for field crops in areas of high greenhouse whitefly incidence (3).

The impact of BPYV on pumpkin production remains to be determined; however, grower data suggest an increased incidence of fruit abortion and a substantial decrease in fruit weight.

To our knowledge, this is the first report of BPYV infecting pumpkin.

References:
(1) J. E. Duffus. Phytopathology 55:450, 1965.
(2) S. Hartono et al. J. Gen. Virol. 84:1007, 2003.
(3) I. E. Tzanetakis et al. Plant Dis. 87:1398, 2003.

[First reported in beet (_Beta vulgaris_) from Salinas, CA, in 1965, BPYV is  spreading in Australia (Tasmania), France, Japan, the Netherlands, USA (California), and more recently reported from Italy, Crete, and possibly Spain. It would appear to be an emerging disease of pumpkin and perhaps  other cucurbits monitored by ProMED-Plant. - Mod.DH]