Legume "Little leaf", a virus disease of subtropical pasture species

Abstract

A virus of legumes causing a disease described as "little leaf" has infected with differing degrees of severity some 40 per cent. of pasture legumes in experimental plots in subtropical Queensland. The symptoms are similar to those caused by the "big bud-witches' broom" complex of viruses of which it is probably another strain. Transmission studies have shown that the vector is the leafhopper Orosius argentatus (Evans) which also transmits tomato "big bud", lucerne "witches' broom", potato "purple top wilt", and tobacco "yellow dwar"' diseases. The O. argentatus taken direct from the field in Queensland, and its progeny reared in the laboratory, were efficient vectors of "little leaf" whereas the Canberra strain bred in the laboratory would not transmit 'little leaf' and was not an efficient vector of the other "yellows" viruses. The majority of species and strains tested in the genera Crotalaria, Desmodium, Indigofera, and Stylosanthes are susceptible to "little leaf". Within such genera there are a few resistant species or strains with promising agronomic characters. Lucerne and white clover are relatively resistant to "little leaf". The genera Arachis, Centrosema, Doliehos, Glycine, Lespedeza, Leucaena, Pueraria, Phaseolus, Vigna, and Zornia contain species and strains with marked field resistance. Most of the species and strains considered to be promising pasture legumes possess field resistance to "little leaf".

Vectors and alternative hosts of Tobacco yellow dwarf virus in southeastern Australia

“…Furthermore, disease occurrence in beans and tobacco could be minimised by targeting herbicide applications to TbYDV host plants such as A. retroflexus and R. raphanistrum that were commonly found in and around crops at the two most disease-affected sites. Apart from TbYDV, O. orientalis also transmits phytoplasmas which cause a range of economically important phytoplasma-associated diseases in Australia such as legume little leaf (Hutton & Grylls, 1956), tomato big bud (Hill & Mandryk, 1954;Osmelak, 1986), lucerne witches broom (Helson, 1951), potato purple top wilt (Grylls, 1979;Harding & Teakle, 1985) and Australian lucerne yellows (Pilkington et al, 2004). Therefore, the results from this study will possibly lead to effective control strategies for not only TbYDV but also phytoplasma diseases vectored by O. orientalis.…”

A revision of the genusOrosiusDistant (Hemiptera: Cicadellidae) based on male genitalia and DNA barcoding

“…The significance of this discovery has implications for studies of disease transmission in Australia. O. argentatus has been cited as a vector for several phytoplasma‐associated diseases in Australia including tomato big bud (Hill ; Bowyer ; but see Pilkington et al ), tobacco yellow dwarf (Hill ; Helson , ), lucerne witches broom (Helson ), legume little leaf (Hutton & Grylls ), potato purple top wilt and pawpaw yellow crinkle (Grylls ; Padovan & Gibb ), Australian lucerne yellows (Pilkington et al ) and equivocally for Australian grapevine yellows (Beanland et al ) and strawberry lethal yellows (Streten et al ). It could be expected that vector studies in eastern Australia are focussed on O. argentatus although care needs to be taken to confirm the identity of any vectors, using COI gene sequencing if necessary, particularly because additional species, three described as new in this paper, are known from southern and eastern Australia.…”

Intraspecific variation within Orosius argentatus Evans (Hemiptera: Cicadellidae): colour polymorphisms, morphometric analyses and host associations

“…In Australia, it is a vector (or a reputed vector) of several diseases caused by phytoplasmas and mycoplasma-like organisms that inhabit the phloem sieve tubes of plants (Bowyer et al 1969;Bowyer & Atherton 1971), and which impact on foliage and seed production in various ways. The diseases include tomato big bud, purple-top wilt of potato, yellow dwarf of tobacco, witches' broom of lucerne, Australian lucerne yellows and little leaf of stylo (Stylosanthes scabra) (Helson 1951;Hutton & Grylls 1956;Bowyer 1974;Davis et al 1997;de la Rue et al 2001;Pilkington et al 2004;Streten & Gibb 2006).…”