27 July 2001
Growers warned of mosaic ‘time bomb’

By Tom Allen-Stevens

BARLEY growers were warned on Friday (27 July) to be on their guard for Barley Mosaic Virus and choose varieties accordingly.

The recent string of mild winters has masked the fact that Barley Mosaic Virus is spreading and lying dormant, according to UAP agronomist Peter Gould.

Symptoms appeared during a cold snap last winter in malting barley on farms throughout the chalklands of Wiltshire, Hampshire and Dorset.

“The colder weather last winter has certainly highlighted the fact that Mosaic Virus is more widespread that we thought,” said Mr Gould.

“Infections were localised, but small patches appeared in crops throughout the region and on farms that we considered to be free of the problem.”

The effects of the disease can be serious, he said, with yields reduced by between 20% and 30%.

Quality is also affected with increases in grain nitrogen contents and screenings. The only way to combat the disease is to plant a resistant variety.

“If we have a cold winter and a subsequent increase in infection, we will be snookered,” he added.

The warning coincides with the release of yield results from trials on Mild Mosaic Virus infected sites, jointly funded by Home-Grown Cereals Authority and Arable Research Centres.

Most resistant barleys performed well, including new feed variety Carat and six rows Siberia and Angela.

Non-resistant Opal performed better than expected, while Leonie, a low-yielding resistant variety, was outperformed by other malting barleys, such as Pearl.

“In a more severe year Leonie would have done much better and Pearl would have been clobbered,” explained ARCs Richard Overthrow.

Barley Yellow Mosaic Virus (BaYMV) and Barley Mild Mosaic Virus (BaMMV) are carried by a soil borne fungus that can survive in the soil for up to 10 years.

The young barley plant is initially infected by either strain during the autumn. The infection then spreads to neighbouring plants.

The symptoms, yellow mottling and streaking on unfurling leaves are triggered by cold, frosty weather during the winter.

The telltale signs at this time of the year are stunted plants and irregular growth.

Name Yield (%age of site mean) Name Yield (%age of site mean) Name Yield (%age of site mean) Name Yield (%age of site mean) Name Yield (%age of site mean)
Carat *120 Siberia * (6 row)113 Angela * (6 row)113 Antonia *110 Jewel *109
Opal109 Muscat * (6 row)107 Haka106 Whisper *105 Jackpot * (6 row)103
Pict * (6 row)101 Avenue *100 Pearl98 Scylla97 Chamomile95
Milena94 Fanfare94 Vanessa94 Vertige94 Leonie *92
Heligan91 Diamond89 Flute89 Regina87 Sumo81
Source: ARC Resistance to BaMMV denoted by *