Barley Yellow Dwarf Virus (BYDV)
BYDV
Pathogen
Virus
Hosts
Barley, wheat, oats
Symptoms
The earliest symptoms are a slight discolouration of the youngest leaves, barley turns golden-yellow, wheat pale yellow and oats purple-red. Plants grow slowly and the discolouration develops further. Late in the season plants are clearly stunted, show extensive tillering, delay in heading and ripening. Grain is shrivelled. The infection is usually patchy throughout the crop.
Development
Volunteer cereals, cultivated and weed grasses act as the source of infection with aphids (particularly the bird cherry aphid and the grain aphid) acting as vectors for the disease. Peak infection time is in late October and early November when crops have emerged and the weather is not severe enough to stop aphid movement and migration.
Favourable factors
Early emerging autumn sown cereal crops particularly in coastal areas of the south, south east and south west which are habitually at high risk from BYDV, but in a mild autumn / early winter almost any part of the UK cereal growing area can suffer damaging infections.
Importance
In trials yield losses to BYDV have been recorded at 30 % in wheat and 75 % in barley. In addition grain can be small and shrivelled.
Control
Insecticide seed treatment which can protect drops for up to 12 weeks.
Control of aphids by pyrethroid insecticides at or just before peak infection time (October).
Reduce potential sources of aphid infection by destroying the green bridge of stubbles and volunteers with total herbicides.
Once symptoms appear it is too late for control measures.
Localised patches
Typical symptoms on wheat leaves
No seed treatment (Photo T. Nicholson)
Typical symptoms on wheat leaves - note the reddening to the leaf tips
