|Kahn, Mohamed - ND STATE UNIVERSITY|
|Nelson, Randy - ND STATE UNIVERSITY|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 4, 2005
Publication Date: June 20, 2006
Citation: Kahn, M.F., Campbell, L.G., Nelson, R. 2005. Effect of fusarium root rot on sugarbeet in Minnesota, USA [abstract.] Proceedings 68th IIRB Congress MECC. http://126.96.36.199. Technical Abstract: Fusarium root rot (yellows) caused by the soil borne fungus, Fusarium oxysporum f. sp. betae, was first confirmed in 2002 as a pathogen of sugar beet in Minnesota and North Dakota. Fusarium oxysporum f. sp. betae survives as chlamydospores that germinate in the presence of sugar beet roots, penetrate, and invade the xylem vessels. Fusarium yellows symptoms first appear on the oldest leaves as interveinal chlorosis, followed by necrosis. Leaves eventually die but remain attached to the crown of the plant. The taproots do not show any external symptoms. Transverse sections through the lower portions of infected roots reveal a grayish brown discoloration of the vascular system. After harvest, sugar beet roots are stored in piles for 6 to 7 months in Minnesota and North Dakota. Roots infected with Fusarium root rot can increase losses in storage piles significantly. In 2004, roots of seven sugar beet cultivars were collected from a research site with severe Fusarium root rot. Roots were washed, placed in polyethylene bags and stored at 4ºC and high humidity. After 30, 60, and 120 d of storage, the root samples were weighed, placed in 23 l pails for 24 h, and respiration rates were determined by measuring the CO2 produced per kg of root per hour. Sucrose concentration and extractable sucrose concentration were determined 30 and 120 d after storage. A rot index, using a scale of 0 (no root rot) to 100 (completely rotted), was used to quantify the amount of rotted tissue 120 d after storage. For the seven cultivars evaluated, the mean respiration rates were 6.49, 8.96 and 19.18 mg CO2/kg root/hr 30, 60 and 120 d after storage, respectively; mean sucrose concentrations were 13.2 and 10.1% after 30 and 120 d, respectively; mean extractable sucrose concentrations were 108 and 68 kg/t after 30 and 120 d, respectively; mean root rot index was 31. The most resistant cultivar had respiration rates of 5.34, 6.32, and 9.47 after 30, 60 and 120 d in storage; sucrose concentrations of 14.8 and 13.6 % after 30 and 120 d in storage, respectively; extractable sucrose concentrations of 125 and 111 kg/t after 30 and 120 d in storage; and a rot index of 12. The most susceptible cultivar had respiration rates of 10.06, 15.43, and 31.78 mg CO2/kg root/hr 30, 60 and 120 d after storage, respectively; sucrose concentrations of 10.6 and 5.4 % after 30 and 120 d in storage, respectively; extractable sucrose concentrations of 79 and 24 kg/t after 30 and 120 d in storage; and a rot index of 63.