Identification and Prevalence of White Clover Viruses and the Resistance of Trifolium Species to These Viruses¹

Abstract

White clover, Trifolium repens L., plants from 19 pastures in eight southern states were collected without regard for symptoms. Viruses infecting these plants were detected and identified by the use of differential hosts and serological techniques. Alfalfa mosaic virus (AMV) was found in 7 pastures, clover yellow vein virus (CYVV) in 15, peanut stunt virus (PSV) in 14, and white clover mosaic virus in 5. Clover yellow mosaic virus was not found. Of 636 plants sampled, 237 were infected with one to three viruses. The percentage of virus‐infected plants in a pasture varied from 0 to 86. How concentrated pastures were in the vicinity, how many years the pasture was in perennial clover, and whether the white clover persisted from year to year, as a perennial plant or by annual reseeding, influenced the amount of virus infection. Twenty‐three Trifolium species were mechanically inoculated with six or seven viruses to find resistant germplasm. Although some variation was detected, all plants of most species were infected. Clover yellow mosaic virus infected 10% of the T. ambiguum Bieb. plants inoculated, whereas no plants were infected with the other 6 viruses. A few white clover plants were resistant to mechanical inoculation with each of the three most prevalent viruses, AMV, CYVV, and PSV.

Estimating the agronomic impact of white clover mosaic virus on white clover performance in the North Island of New Zealand

“…Furthermore, although high levels of WC1MV have been reported in some overseas studies (Khadhair & Sinha 1982;Alconero 1983;Garrett 1991;Sherwood 1997), the levels of incidence found in the North Island are generally higher than those reported in overseas studies on various perennial Trifolium spp. (Gibbs et al 1966;Barnett & Gibson 1975;Gates & Bronskill 1974;Jones & Diachun 1976;McLaughlin & Boykin 1988;McLaughlin & Ensign 1989;Potter 1993).…”

Managing Intermountain rangelands - improvement of range and wildlife habitats: proceedings; 1981 September 15-17; Twin Falls, ID; 1982 June 22-24; Elko, NV

“…It is a coldhardy, drought tolerant, rhizomatous perennial which is also resistant to several virus diseases which attack other clovers (Barnett and Gibson 1975). However, early experiences with this species resulted in stand failure because of weak seedlings and a lack of nodulat~on.…”

Development of a breeding strategy for interspecific hybrids between Caucasian clover and white clover

“…has several high persistence traits that complement the disadvantages in white clover including a strong root system and rhizomes (Forde et al 1989) and resistances to several nematode and virus diseases (Barnett & Gibson 1975;Mercer 1988). However, it is slow establishing, has very specific rhizobial inoculation requirements and has poor seed-set (Pryor et al 1998;Taylor & Smith 1998).…”