Effect of Barley yellow dwarf virus Infection on Yield and Malting Quality of Barley

Barley yellow dwarf (BYD), the most common and widespread virus disease of cereal crops worldwide (14), may be caused by any one of several Barley yellow dwarf viruses (BYDVs) of the family Luteoviridae. Transmitted by at least 25 aphid species (24), these viruses historically have been classified into two subgroups and five strains based on aphid vector specificity and efficiency (31). However, each is now considered a member of the genus Luteovirus or Polerovirus, or is not yet assigned to a genus (37). BYDV-PAV, classified in the genus Luteovirus, is the predominant strain in North America, with the bird cherry-oat aphid (Rhopalosiphum padi L.) being its most efficient vector (25). BYDVs have a large host range, infecting many grass species in the family Poaceae and all major cereal crops (15). Yield losses in the United States have been estimated at 1 to 3% annually (11) but, under environmental conditions favorable for the pathogen, losses up to 40% are not uncommon (10). In the Upper Midwest region of the United States, where most of this country’s malting barley production is concentrated, BYDV infection occurs frequently, but is rarely severe. However, in 1999, a widespread and severe BYD disease epidemic occurred on barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), and oat (Avena sativa L.) in North Dakota, South Dakota, and Minnesota (B. Steffenson and M. McMullen, unpublished data). Late planting, combined with the early arrival of viruliferous aphids, contributed to this epidemic. Many studies have been conducted to determine the effect of BYD disease on yield in cereal crops (4,5,8,19,23,26,39). Oat is considered the cereal most susceptible to crop loss due to BYD disease, while barley is the second most damaged crop (33). In fact, infection of barley at the seedling stage can result in up to 93% yield loss after artificial inoculation with BYDVs in field plots (6). Although many studies have been published on yield loss due to BYDV infection of oat and wheat, relatively little information is available on the effect of BYD disease on spring barley, especially malting cultivars. In addition to direct losses in yield, barley producers may incur losses due to a reduction in quality. The number of quality requirements is greater for malting barley than for any other crop (9), and substantial price discounts can occur if the harvested grain is downgraded from premium malting-type to feed-type barley as a result of an inability to meet stringent malting quality standards. However, the effect of BYDV infection on malting quality components has not been adequately studied. The objective of this research was to determine the effect of BYDV infection on the yield and malting quality of three barley cultivars grown in the Upper Midwest region of the United States.