Plant Pathology: Extension: Plant Disease Library

Barley Yellow Dwarf (BYD) - Barley yellow dwarf virus

Barley - Hordeum vulgare
Oats - Avena sativa
Wheat - Triticum aestivum

Disease Symptoms:
Symptoms always develop from the leaf tip towards the base often with the entire width of the leaf affected. Barley develops bright yellow symptoms. Symptoms on oats are reddish and the disease on oats is sometimes called "red leaf". Leaf symptoms on wheat vary from yellow to red or purple and vary with the cultivar. These symptoms may be similar to those caused by nutrient imbalances. If infection occurs in the autumn, oats and barley are often severely stunted. Affected wheat plants are reduced in size a few inches and heads have fewer seeds than healthy plants. Picture 1 - Wheat plants showing "Red Leaf".

Signs:
Barley yellow dwarf virus is transmitted by several species of aphids from grassy weeds to small grains. The presence of large numbers on aphids on plants does nor necessarily mean BYD is present.

Barley showing typical yellowing symptoms.

Disease Management:
Crop rotation reduces the disease by reducing the population of aphid vectors. Few cultivars are highly resistant to BYD and yield loss may not be directly related to symptom severity (see the annual CAES Small Grains Performance Tests Research Report or the annual Wheat Production Guide). Plant toward the end of the recommended period to reduce fall infection. Control grassy weeds during the summer in fields where susceptible small grains are to be planted and mow grasses along edges of fields to reduce aphid populations. Fall-applied insecticides are being evaluated which may reduce yield loss.

Compiled by: Barry M. Cunfer, UGA Plant Pathologist, Griffin, GA