IN Canterbury lucerne is generally established in 7 in. rows, without companion species, by drilling inoculated lucerne seed with matured lime-reverted superphosphate into an adequately cultivated and limed seedbed (Anon, 1958). As the crop ages, other species establish voluntarily so that eventually a mixed association of lucerne and variable proportions of grasses, clovers and other herbs results (Blair, 1965). The point at which volunteer species establish in the lucerne crop varies, and, although many crops remain free from other species for several years, some become infested during their establishment phase (Allen, 1967). The establishment and persistence of volunteers in the lucerne crop are affected by a wide range of factors such as the occurrence of lucerne diseases and pests (Blair, 1968), the variety of lucerne sown (Lobb, 1969), harvest and grazing management (Keoghan, 1967; O'Connor and Vartha, 1968), and applications of fertilizers (Sewell, 1960; Stephen, 1964; Harris, et al., 1966).
