Yield put at risk
Yield put at risk
Soil-borne viruses are a growing threat to both wheat and barley. Tom Allen-Stevens reports.
IF YOUR soil is infected with one of the cereal viruses and you dont know about it, you could be losing out twice. Not only will there be perennial yield losses, youll be wasting money on the wrong cures.
According to Mike Carver of Arable Research Centres (ARC), the barley yellow mosaic virus (BaYMV) is often misdiagnosed because the symptoms are very similar to other problems such as transient nitrogen or manganese deficiency, or water-logging.
"Look for parallel, yellow tramlining on the leaves. Its distinctive because its the young, developing leaves that are pale and streaky," says Dr Carver. "The disease is now exceptionally widespread throughout the UK – every barley-growing county has suffered incidences."
First reported in 1980, BaYMV has spread quickly. A second virus, barley mild mosaic virus (BaMMV), has also been identified and there is no known cure for either. However, some varieties are resistant, and this is the only protection.
HGCA-funded research into resistant varieties has been carried out by Dr Carver and his team in collaboration with IACR Rothamsted. They have discovered that the yield variations can be huge: "If you have BMV, you virtually have to rewrite the NIAB Recommended List, because of the variation. While the mean yield does not drop too much, individual varieties can suffer enormously; the spread of yields on our infected trial sites has been much greater than the spread on NIAB plots," says Dr Carver.
ARC is also collaborating with Central Sciences Laboratory to evaluate a rapid field testing kit. The aim is to give a diagnosis in five minutes.
Such rapid diagnostic techniques may prove essential defence tactics against the new soil-borne wheat mosaic virus (SBWMV), which has been confirmed in Wiltshire. There are worrying indications that this virus could spread as rapidly as BaYMV.
An ARC trial has now been set up on the infected farm. There is also an HGCA-funded trial under way, in collaboration with NIAB.
Losses can be severe: up to 40%. Current indications are that Charger has a level of resistance to SBWMV infection.
Variety NIAB 99 ARC ARC
one-year BaYMV BaMMV
results site site
Mean yield (t/ha) 8.07 7.84 7.00
(yield as % of site mean)
Laurel n/a 119 126
Jewel 103 114 115
Intro 99 112 114
Hanna 102 111 90
Vanessa* 101 110 100
Mariner n/a 108 99
Heligan 99 107 91
Siberia 112 107 105
Vertige 99 105 77
Fanfare 100 103 107
Epic 95 103 98
Gleam 103 100 105
Antonia 102 99 101
Angela 107 98 93
Muscat 105 95 111
Flute 96 94 100
Rifle 101 90 100
Halcyon 90 89 87
Pearl 103 82 n/a
Regina 103 78 99
Artist 94 76 90
*some resistance to mild mosaic
Red: Mosaic virus resistant
Source: ARC and NIAB