Barley Yellow Dwarf Virus (BYDV)

Pathogen

Barley yellow dwarf virus

Hosts

The disease affects all cereals and grasses. Barley and oats are usually more severely affected than wheat.

Symptoms

The initial symptoms of BYDV infection are normally seen as individual plants scattered through the crop with bright yellow upper leaves. Later, as infection spreads, larger areas of the crop become infected appearing as patches of bright yellow and severely stunted plants. BYDV is most damaging to plants infected in the early growth stages. The effects of BYDV may be exacerbated by other stress factors, including adverse weather conditions, soil acidity and other pests and diseases.

Life Cycle

BYDV-life-cycle.jpg

BYDV became very much more important and widespread with the increase in early-drilling of winter cereals. The virus exists as several strains and is transmitted by various species of cereal aphid. The bird-cherry aphid (Rhopalosiphum padi) is the principal vector in the south of England. In the north of England and in the Midlands the grain aphid (Sitobion avenae ) is usually more important.

In the autumn, BYDV can be introduced into cereal crops in two ways:-

  1. Direct transfer by wingless aphids living on grass or on volunteer cereals which survive cultivation and move through the soil colonising the following cereal crop. This is much more common in coastal areas of the south west where cereals may follow grass and winters can be mild.
  2. Indirect transfer by winged aphids migrating into newly emerged crops from grass or volunteer cereals elsewhere. BYDV introduced by winged aphids flying into crops is generally more common and important than BYDV resulting from direct transfer.

Importance

With the now common practise of sowing winter cereals very early, BYDV has increased in importance in many areas of the UK. The frequency of very mild winters has also meant that, for many farms, BYDV is now a regular problem. Early infections can kill patches of plants potentially resulting in large yield losses.

Cultural control

  1. Direct transfer: Appropriate, timely cultivations - ploughing at least 3 weeks before drilling, burying or destroying trash completely and preparing well consolidated seedbeds will minimise the risk of direct transfer.
  2. Indirect transfer: Late drilled crops are generally less affected than those drilled early and some localities are less BYDV-prone than others. The damage caused by BYDV infection can be minimised by delaying sowing of cereals until the middle of October. In most years such crops escape the aphid colonisation which brings virus so that no preventative spraying need be considered. In some years few crops warrant treatment.

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BYDV management tool

BYDV management tool