Yield Losses Caused by Barley Yellow Dwarf Virus-PAV Infection in Wheat and Barley: A Three-Year Field Study in South-Eastern Australia

Barley yellow dwarf virus (BYDV) is transmitted by aphids and significantly reduces the yield and quality of cereals worldwide. Four experiments investigating the effects of barley yellow dwarf virus-PAV (BYDV-PAV) infection on either wheat or barley were conducted over three years (2015, 2017, and 2018) under typical field conditions in South-Eastern Australia. Plants inoculated with BYDV-PAV using viruliferous aphids (Rhopalosiphum padi) were harvested at maturity then grain yield and yield components were measured. Compared to the non-inoculated control, virus infection severely reduced grain yield by up to 84% (1358 kg/ha) in wheat and 64% (1456 kg/ha) in barley. The yield component most affected by virus infection was grain number, which accounted for a large proportion of the yield loss. There were no significant differences between early (seedling stage) and later (early-tillering stage) infection for any of the parameters measured (plant height, biomass, yield, grain number, 1000-grain weight or grain size) for either wheat or barley. Additionally, this study provides an estimated yield loss value, or impact factor, of 0.91% (72 kg/ha) for each one percent increase in natural BYDV-PAV background infection. Yield losses varied considerably between experiments, demonstrating the important role of cultivar and environmental factors in BYDV epidemiology and highlighting the importance of conducting these experiments under varying conditions for specific cultivar–vector–virus combinations.

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Role of winter-active aphids spreading Barley yellow dwarf virus in decreasing wheat yields in a Mediterranean-type environment

Australian Journal of Agricultural Research ◽

10.1071/ar05048 ◽

2005 ◽

Vol 56 (10) ◽

pp. 1089 ◽

Cited By ~ 19

Author(s):

Deborah J. Thackray ◽

Laura T. Ward ◽

Monica L. Thomas-Carroll ◽

Roger A. C. Jones

Keyword(s):

Virus Infection ◽

Barley Yellow Dwarf Virus ◽

Yellow Dwarf ◽

Dwarf Virus ◽

Virus Spread ◽

Yield Losses ◽

Barley Yellow Dwarf ◽

Virus Incidence ◽

Aphid Vectors ◽

Yellow Dwarf Virus

In the grainbelt of south-western Australia, which experiences Mediterranean-type climatic conditions, 3 field experiments with wheat were sown in autumn, 2 at Site A over 2 years and 1 at Site B in the first year only. These experiments related both activity of aphid vectors (migration into and colonisation of wheat) and the spread of infection with Barley yellow dwarf virus (BYDV) serotype PAV to wheat grain yield and quality. Incidences of BYDV serotype RMV and Cereal yellow dwarf (CYDV) were mostly low and BYDV serotype MAV was not distinguished. Rhopalosiphum padi was the predominant vector species but small numbers of R. maidis and Sitobion miscanthi were also present. Repeated insecticide spray applications began at different times in the different experimental treatments. These sprays killed or repelled aphid vectors, thereby preventing further virus spread from the time they were first applied. At both sites, migrant aphids were caught flying into the wheat throughout the winter period. Peak numbers of colonising aphids ranged from 0 to 99/0.5-m transect of crop. BYDV-PAV incidence ranged from 0.1 to 58% of plants and yields ranged from 1.9 to 8.6 t/ha. First aphid arrival was earlier, and virus spread and resulting yield losses greater at Site A. At this site, in treatments where repeated insecticide sprays did not start until 8 weeks after crop emergence (WAE), virus incidence and subsequent yield losses were significantly greater than when the regular applications started at emergence. However, delaying the start of sprays beyond 8 weeks had no further effect on virus spread. Since aphid numbers were very low up to 8–10 WAE, yield losses were due entirely to virus infection of plants during this early growth period. Variation in BYDV-PAV incidence explained 81 or 91% of the variation in yield gaps in the 2 years at Site A where, for each 1% increase in virus incidence, there was a yield decrease of 55 or 72 kg/ha. It also explained the variation in seed weight (88%) and protein content (69%), but not in seed screenings. At Site B, virus spread started too late to cause significant yield or quality losses. These results show that wheat yields are decreased substantially in a Mediterranean-type environment, when aphids immigrate early into wheat crops and remain active throughout the winter-growing period, spreading virus infection at young plant growth stages.

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