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Early History:
During the early part of the 20th century, a severe disease persisted in
the sugarbeet growing areas of the western United States. This malady destroyed one-third
of the 1925 sugarbeet crop in the Sacramento Valley. During this same period, the disease
greatly reduced sugarbeet yields on the west side of the San Joaquin Valley and in the
southern part of the Salinas Valley. The disease has sporadically devastated Washakie
County, Wyo., limiting yields to as little as two tons per acre. Up until 1930, three
sugarbeet factories in the Snake River Valley had never run at more than 50% of their
capacity due to severe yield losses caused by this disease. Even today, the disease
continues to cause devastating losses as witnessed by recent epidemics in Wyoming, Idaho,
and in the San Joaquin Valley. The disease is Curly Top.
During the early years of the development of the western sugar beet
industry, no effective methods of control existed, and the industry experiences extremely
heavy losses. Total destruction of susceptible crops occurred in some areas in certain
years. A big breakthrough in control came with the development of sugarbeet varieties
resistant to BCTV. Sugarbeet breeders had for years searched for varieties resistant to
curly top. In 1934, the USDA released the first resistant variety, US1. Other improved
resistant varieties followed and today variety resistance is the backbone of curly top
control.
Development of Resistant
Varieties
The Sugar Beet Development Foundation maintains a Curly Top nursery in
Kimberly, Idaho. All sugarbeet seed companies enter their breeding lines and varieties in
the nursery for resistance evaluation. In 1993, the nursery consisted of a 6-acre plot and
evaluations were made on 2,088 entries for Curly Top resistance. Most modern Curly Top
resistance varieties are being selected from this nursery.
BCTV also causes disease on several other crop plants besides sugar
beets. Crop susceptible to damage include tomato, bean, flax, potato, cucurbits and
tobacco. Many different strains of BCTV occur and differ in virulence, symptoms and host
range.
to BCTV main article
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