<P> Sugar beet plants are susceptible to Rhizomania ("root madness"), which turns the bulbous tap root into many small roots, making the crop economically unprocessable . Strict controls are enforced in European countries to prevent the spread, but it is already endemic in some areas . It is also susceptible to the beet leaf curl virus, which causes crinkling and stunting of the leaves . </P> <P> Continual research looks for varieties with resistance, as well as increased sugar yield . Sugar beet breeding research in the United States is most prominently conducted at various USDA Agricultural Research Stations, including one in Fort Collins, Colorado, headed by Linda Hanson and Leonard Panella; one in Fargo, North Dakota, headed by John Wieland; and one at Michigan State University in East Lansing, Michigan, headed by J. Mitchell McGrath . </P> <P> Other economically important members of the Chenopodioideae subfamily: </P> <Ul> <Li> Beetroot </Li> <Li> Chard </Li> <Li> Mangelwurzel or fodder beet . </Li> </Ul>

Where are sugar beets grown in the us