Compendium of Potato Diseases - (PDF, 101 mb) - USAID

Control
I) Use IPVX-free seed and avoid contamination through
contact with infected plants or tubers.
2) Use resistant cultivars where possible. Tolerant cultivars
are useful. Many high yielding seed stocks, completely infected
with PVX, produce plants with excellent vine type and high
tuber quality.
Selected References
BERCKS. R. 1970. Potato Virus X. No. 4 in: Descriptions of Plant
Viruses. Commonw. Mycol. Inst., Assoc. Appl. Biol.. Kew,Surrey,
England.
COCKERItAM, G.1954. XIII. Strains of potato virus X. Pages 82-92
in: E. Streutgers. A. B. R. Beemster. 1). Noordam, and 1.P. H. Van
der Want, eds. 1955. Proc. Second Corf. Potato Virus Dis., 25-29
June, 1954. H. Veenman and Zonen, lisse-Wageningen, rhe
Netherlands. 193 pp.
COCKERIHAM, G. 1970. Gcenetical studies on resistance to potato
viruses X and Y. Hteredity 25:309-348.
DEI.HEY. R. 1974. Zur Natur der cxtremen Virusresisten, bei der
Kartoffel. Phytopathol. Z. 80:97-119
MEI.LOR, F. C., and R. SIACE-SMIIlI. 1970. Virus strain
differences in eradication of viruses X and S. Phytopathology
60:1587-1590.
MOREIRA, A.. R. A. C. JONES. and C. E. FRIBOURG. 1980.
Properties of a resistance-breaking strain of potato virus X. Ann.
Appl. Biol. 95:93-103.
MUNRO,,1. 1954. Maintenanceof virus X-free potatoes. Am. PotatoJ.
31:73-82.
MUNRO. .1.1961. The importance of potato virus X. Am. Potato J.
38:440-447.
SHALLA. "L A.. and .1. F. SHEPARD. 1972. The structure and
antigenic analysis of amorphous inclusion bodies induced by potato
virus X. Virology 49:654-657.
SHEPARDJ. F.and G.A. SECOR. 1969. )etection ofpotatovirus X
in infected plant tissue by radial and double-diffusion tests in agar.
Phytopathology 59:1838-1844.
WRIGHT, N.S.1970. Combined effects of potato viruses X and S on
yield of Netted Gem and White Rose potatoes. Am. Potato J.
47:475-478.
(Prepared by J. Munro)
Potato Virus M
Potato virus M (PVM) isfound worldwide in potato cultivars.
It is more important in Eastern Europe and the USSR than in
other parts of the world. Its economic significance in North
.- ~c:..America is uncertain.
The disease was first named potato leafrolling mosaic. Early
descriptions were probably not made on PVM alone because the
J%. virus frequently occurs with potato viruses X and/or S. The
identity of PVM has only recently been clearly established.
7 "PVM causes the latent paracrinkle disease in the King Edward
cultivar.
K
. .
Symptoms
Aboveground symptoms range from very slight to severe
(Fig. 79 A-C, Plate 63) and include mottle, mosaic, crinkling,
and rolling of leaves; stunting of shoots; leaflet deformation and
twisting; and some rolling of the top of the plant. Severity is
influenced by virus strain, potato cultivar, and environmental
conditions. Necrosis of petioles and stems may develop in
certain potato cultivars.
- .PVM
S -nm.
Fig. 78. Potato virus X infections: A, Gomphrena globosa; B,
Causal Agent
particles are straight to slightly flexuous rods 650 X 12
The thermal inactivation point is between 65 and 70°C;
dilution end point is 10-2-10-4;
20
and infectivity is retained at
0 Samsun tobacco; C, Havana tobacco inoculated leaf with
clear ring spots and leaf of same plantwith systemic vcin clearing.
D,Electron micrograph of potato virus X particles (X83,000). (B,
Courtesy J. Munro)
C for two to four days. The virus is a good immunogen.
Cytopathology and Histopathology
Numerous PVM rods and virus aggregates occur in the
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