Beet western yellows virus: high infection in south-eastern Australia

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1 Beet western yellows virus: high infection in south-eastern Australia Mohammad Aftab, Joop vanleur, Jenny Davidson, Angela Freeman, Brendan Rodoni and Piotr Trebicki

2 Beet western yellows virus (BWYV) synonym Turnip yellows virus (TuYV) This is the most important virus disease of oilseed rape and pulse crops in south eastern Australia and belongs to genus Polerovirus family Luteoviridae The BWYV strains which do not infect sugarbeet are called TuYV The virus is persistent and is only transmitted by aphids The most efficient aphid vector of this virus is Myzus persicae Host range of this virus is very wide and infects many plant families and weed species

3 Symptoms of BWYV on canola Purple leaves Chlorosis of leaves

4 44Y25 RR Turnip Crusher TT ATR Bonito

5 Widespread outbreak of BWYV on canola crops in South Australia In 2014 a widespread outbreak of BWYV occurred on canola crops in lower and mid North regions of South Australia (SA) early in the season The virus badly infected an area of hectares with the crop losses ranged % in SA With the confirmation of virus large scale passive canola surveys were conducted in South Australia (8088), NSW (4359) and Victoria (1338) All survey samples were tested at DEDJTR Horsham for BWYV using tissue blot immunoassay with commercial polyclonal antisera from SEDIAG France

6 Virus survey sites in south eastern Australia

7 High infection of BWYV on canola crops in NSW, SA and Victoria

8 Possible factors for the epidemic of BWYV Summer rainfall resulting in increased green bridge for virus and vectors Above average temperature in May and June Large flights of green peach aphid early in the season Limited use of insecticide seed dressing Insecticide resistance in green peach aphid

9 Percent infection SA winter and spring weed survey for BWYV

10 BWYV symptoms on weeds Marsh Mallow Bifora Wild Radish Musk weed

11 BWYV diagnostic submitted canola samples in 2015 Variety State Region % Infection ATR Bonito NSW Deniliquin 77 Crusher TT NSW Deniliquin 65 Garnet NSW Deniliquin Y 25 RR NSA Deniliquin 33 SF Brazil VIC Geelong 100 Victory VIC Hamilton 0 ATR Bonito VIC Horsham 25 Crusher TT VIC Nullawil 0 44 Y 84 CL VIC Swan Hill 0 Edimax CL SA Millicent 11

12 Aphids feeding on canola Myzus persicae Brevicoryne brassicae Brevicoryne pseudobrassicae

13 Glasshouse Experiments Thirteen canola and Brassica juncea varieties were inoculated with BWYV canola isolate using Myzus persicae The main purpose of glasshouse experiments was to check the transmissibility of the virus 54 marsh mallow plants were inoculated to preserve the virus isolate as a positive control to keep for long term

14 Percent Infection Glasshouse Inoculation of canola and Brassica juncea varieties and Marsh Mallow

15 Symptoms on glasshouse inoculated plants Sahara Marsh Mallow 45Y86 CL Hyola 50

16 Integrated Management of BWYV Resistance varieties Weed control Removal of green bridge Sowing into standing stubbles Insecticide seed dressing In crop aphid control based on continuous monitoring

17 Further Studies Collection of canola and pulse BWYV isolates Biological indexing and host range studies of different isolates Molecular studies to see the difference in sequence of different BWYV strains Differentiate the canola, pulse and sugarbeet infecting strains of BWYV and TuYV Field trials for yield loss studies Breeding canola and pulses for resistance to BWYV/TuYV

18 Acknowledgements This research was funded by GRDC and DEDJTR Victorian projects: DAV 129, DAV 134 and SARDI DAS Project We thank Kurt Lindbeck for southern NSW samples Frank Henry for agronomist samples Technical staff at SARDI for processing of samples extensionaus for mapping sample sites