Impact
Barley yellow dwarf (BYD) is caused by several related viruses. The infection is carried and transmitted by the oatbird cherry aphid, corn leaf aphid, English grain aphid, rose grass aphid, and greenbug. The Russian wheat aphid does not transmit the barley yellow dwarf virus.

Yield losses are proportional to the percentage of plants infected by the virus and the growth stage at infection. Early infection may result in high losses.

All small grains can be affected by BYD. The greatest impact of BYD in the San Luis Valley is to late-planted oat hay due to the typically late arrival of aphid populations. BYD in oats is commonly called red leaf.

Description and Symptoms

The principal symptoms of BYD include leaf chlorosis, reduced root growth, and general stunting.

The distinctive symptom of BYD is a bright yellowing of the leaf tips and margins and reddening in oats.

Discoloration begins at the leaf tips, then enlarges toward the base of the leaf. The mid-rib area commonly stays green the longest.

Severity of the infection directly affects the degree of stunting or "dwarfing."

Shortened leaves and poor head development occur in severe cases.

Integrated Management

Use resistant varieties when available.

Plant early to permit crop development prior to aphid flights.

Avoid moisture stress and nitrogen deficiencies to ensure rapid growth and reduce the severity of BYD in infected grains.

Scout for aphids in late-planted grains.

This material is based on work supported by the San Luis Valley Water Quality Demonstration Project Best Management Practices Advisory Committee, Colorado State University Cooperative Extension, Farm Service Agency, Natural Resources Conservation Service, and the U.S. Department of Agriculture under authorization as 1991 U.S. Department of Agriculture Water Quality Demonstration Project.