Variation in white clover for resistance to clover cyst nematode

Abstract

The clover cyst nematode (Heterodera trifolii) infects white clover (Trifolium repens) in pasture throughout New Zealand, reducing plant growth and nutrition. The preferred control method for both economic and ecological reasons is to breed resistant cultivars, with resistance measured as a reduction in cysts/g of root dry weight. Many New Zealand and overseas white clover seed lines and cultivars were screened for resistance. There were highly significant differences between lines for number of cysts, root weight, and cysts/g of root dry weight. Selected genotypes were rescreened using five stolon tips per genotype, and the results were correlated with the first screening. There were high correlations between the number of cysts/plant and cysts/g of root dry weight for all screenings. Two Italian Ladino cultivars were generally among the most resistant lines, as was a line bred for H. trifolii resistance in the Netherlands. There were no immune plants, but the results and the calculated broad sense heritabilities indicate that breeding for resistance is possible.

Review: World checklist of white clover varieties II

“…More susceptible to mosaic viruses than other cultivars tested in Australia (Clark et al 1986). Moderately resistant to root-knot nematode in New Zealand (van den Bosch & Mercer 1996b). Good resistance to clover cyst nematode {Heterodora trifolii) (van den Bosch et al 1996).…”

“…From 20% (Cook & Evans 1988) to 50% "of plants (Cook et al 1992) were resistant to stem nematode. Susceptible to root-knot nematode in New Zealand (van den Bosch & Mercer 1996b). High incidence of CYVV-, A1MV-, and WClMV-infected plants in Czech Republic (Musil et al 1986).…”

“…(Mowat & Shakeel 1989). Moderately resistant to root-knot nematode in New Zealand (van den Bosch & Mercer 1996b).…”

“…Moderately resistant to root-knot nematode in New Zealand (van den Bosch & Mercer 1996b (Zeven 1991). DUTCH WHITE (Inlandse witte klaver) belongs to the group of WITTE CULTUURK-LAVER (Cultivated White Clover race hollandicum) (Zeven 1991).…”

“…Highly susceptible to clover cyst nematode {Heterodera trifolii) in New Zealand (van den Bosch et al 1996).…”