Virus diseases of subterranean clover

Abstract

Subterranean clover (Trifolium subterraneum) is grown as a pasture legume in several temperate regions of the world where the soils are acidic and infertile, and the rainfall is winter dominant and less than 600 mm annually. It is particularly important in southern Australia where more than 16 million ha have been sown with this species as the pasture legume component.Nine viruses have been recorded infecting subterranean clover in the field. These are alfalfa mosaic, bean yellow mosaic (pea mosaic), beet western yellows, clover yellow vein, cucumber mosaic, pea enation mosaic, soybean dwarf (subterranean clover red leaf), subterranean clover mottle and white clover mosaic. In addition there is an important problem referred to as subterranean clover stunt that was assumed to be caused by a virus but whose aetiology is still unknown. The importance of these diseases is reviewed and details on their epidemiologies are outlined together with details on progress towards their control and some comments on matters worthy of attention in the future. Reference is also made to several exotic viruses known to infect subterranean clover experimentally that could possible cause problems if introduced into Australia.

Agrobacterium-Mediated Transformation of Subterranean Clover (Trifolium subterraneum L.)

“…In Australia, subterranean clover is the major pasture legume and is grown on more than 16 million ha of mainly acidic and infertile lands. As a pasture crop and because of its ability to fix nitrogen, subterranean clover is a major contributor to the productivity of the meat, wool, dairy, and wheat industries in Australia (Johnstone and McLean, 1987). It also has the potential to be grown in other temperate regions of the world.…”

Flight activity and weed hosts of Macrosiphini (Homoptera: Aphididae) in Canterbury

“…solani. M. euphorbiae and A. pisum are also reported as vectors, but their importance is unknown (Johnstone & McLean 1987). SDV hosts favoured by A. solani comprise white clover and dock (Table 2).…”

“…AMY, a non-persistent virus of lucerne, white clover, peas and beans, is transmitted by A. kondoi, A. pisum and A. solani (Johnstone & McLean 1987).…”

“…Weed hosts comprise clovers, including white clover, storksbill, dock, mallow and groundsel (Ashby et al 1979;Johnstone & McLean 1987). The main vectoris considered to beA.…”

“…Research on cereal aphids included studies of the control of Sitobion miscanthi Takahashi with insecticides (Sanderson & Mulholland 1970) and transmission of barley yellow dwarf virus (BYDV) by this aphid (Smith et al 1968). Later work on cereals was concerned with Metopolophium dirhodum (Walker) control (Stufkens & Farrell 1984, 1985a, BYDV transmission by this species (Stufkens & Farrell 1986, 1987 and populations of M. dirhodumon barley (Farrell & Stufkens in press). Research on aphid feeding damage to lucerne has included studies on Acyrthosiphon kondoi (Shinji) and Acyrthosiphon pisum (Harris) populations and their control (Kain et al 1976(Kain et al , 1979a(Kain et al , 1979bGaynor et al 1980;Rohitha et al 1985) and lucerne resistance to these aphids (Farrell & S tufkens 1981).…”