|Rush, Charles - TEXAS A&M, AG EXPER STA|
|Jones, David - TEXAS A&M, AG EXPER STA|
|Steddom, Kark - TEXAS A&M, AP EXPER STA|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 28, 2004
Publication Date: September 1, 2005
Citation: Rush, C.M., Jones, D.C., Steddom, K., Campbell, L.G. 2005. Investigation of blinkers in rhizomania resistant fields in minnesota [Abstract]. Journal of Sugar Beet Research. 42(1&2):54-55. Technical Abstract: Since rhizomania was first identified in Minnesota in the mid 1990’s, acreage planted to rhizomania resistant sugar beet cultivars has increased steadily. In recent years individual beets have been observed in rhizomania resistant fields that exhibit foliar and root symptoms typical of rhizomania. These symptomatic beets are called blinkers and their incidence has increased during the last two growing seasons. This increase has raised concerns among farmers and seed producers about the stability and longevity of genetic resistance. In September, 2004, sugar beets were collected from rhizomania resistant fields in southern and northern Minnesota. Ten sugar beets, eight blinkers and two apparently healthy, were harvested from each field and a total of 390 sugar beets were collected. Each sugar beet was given a disease rating, tested for presence of BNYVV, scanned with a hyperspectral radiometer to determine the severity of leaf chlorosis, and tested for presence of absence of the Rz gene that confers resistance to rhizomania. Later, percent sucrose was determined for the liners and healthy beets from each sample. Forty eight percent of the apparently healthy beets tested positive for BNYVV but 88$ of blinkers were positive. The mean rhizomania severity rating for th blinkers was 2.98 on a 0 = 4 scale, while the rating for healthy beet was significantly less at 1.2. The mean ELISA reading for bliners was significantly higher than for infected “healthy” beets and healthy beets average 15.62 percent sucrose compared to 13.95 for blinkers. If molecular analysis reveals that blinkers are lacking the Rz gene these results will support the claim that rhizomania is causing significant losses throughout the major sugar beet production areas of Minnesota, but if the Rz gene is present it will suggest that genetic resistance is breaking down.