Author
NELSON, BERLIN - North Dakota State University | |
Bolton, Melvin | |
LOPEZ-NICORA, HORACIO - The Ohio State University | |
NIBLACK, TERRY - The Ohio State University | |
DEL RIO MENDOZA, LUIS - North Dakota State University |
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/27/2012 Publication Date: 5/1/2012 Citation: Nelson, B.D., Bolton, M.D., Lopez-Nicora, H.D., Niblack, T.L., Del Rio Mendoza, L. 2012. First confirmed report of sugar beet cyst nematode, Heterodera schachtii, in North Dakota. Plant Disease. 96(5):772. Interpretive Summary: Sugar beet and canola are major cops in North Dakota with sugar beet production primarily in the eastern part of the state in the Red River Valley and canola production along the northern half of the state from east to west. Both crops are hosts of sugar beet cyst nematode (SBCN). Sugar beet growers in the Yellowstone Valley of North Dakota near the Montana border reported to us that cysts were observed on sugar beet. Soil samples were collected from four sugar beet fields in that area in April 2011. Cysts were extracted by sieving and nematode-like cysts with eggs were observed in all four soil samples. Population densities in the four fields ranged from 100 to 1,750 eggs/100 cm3 soil. Live females were produced for species identification. Sugar beet and canola seedlings were inoculated and shown to have reproduction by the nematode. A number of measurements of the nematode body were taken and were used to identify the causal agent of as SBCN. Confirmation of identification was by amplification and sequencing of a gene fragment from individual females. This is the first confirmed report of SBCN in North Dakota. SBCN was not detected in North Dakota in a 2001 survey of the principal sugar beet production area of the Red River Valley. Because there is extensive canola production across the northern part of the state bordering western and eastern sugar beet production areas, canola may serve as a bridge for movement of SBCN from west to east. Damage due to SBCN is well known in sugar beet, but there has been limited research on the effects of SBCN on canola. SBCN is a potential threat to these two important crops. Technical Abstract: Sugar beet (Beta vulgaris L.) and canola (Brassica napus L.) are major cops in North Dakota with sugar beet production primarily in the eastern part of the state in the Red River Valley and canola production along the northern half of the state from east to west. Both crops are hosts of sugar beet cyst nematode (SBCN), Heterodera schachtii Schmidt. Sugar beet growers in the Yellowstone Valley of North Dakota near the Montana border reported to us that cysts were observed on sugar beet. Soil samples were collected from four sugar beet fields in that area in April 2011. Cysts were extracted by sieving and Heterodera-like cysts with eggs were observed in all four soil samples. Population densities in the four fields ranged from 100 to 1,750 eggs/100 cm3 soil. Live females were produced for species identification. Sugar beet seedlings (cv. M832224) were grown in a potting mix for 6 weeks in the greenhouse then transferred to Conetainers (Type D40; volume 656 ml) containing autoclaved river sand. Conetainers were placed in sand in plastic pots immersed in a water bath at 27° C. Three plants were each infested with 800 eggs from field No. 2. After 55 days incubation the average number of females was 115/plant. A similar experiment was conducted with three canola cultivars. Germinating seeds were placed in sand in Conetainers and 500 eggs from field No. 2 were placed around three seeds of each cultivar. After 53 days incubation, the average number of females per plant was 39, 20, and 30 for the cultivars Hyclass 940, Caliber 30 and Westar, respectively. Flask-shaped cysts (n=26) from canola roots were light to dark brown; the vulval was cone ambifinestrate with dark brown molar-shaped bullae positioned underneath the vulval bridge. Body length (excluding neck) ranged from 600 to 850 µm (mean 701.2 µm); body width, 350 to 580 µm (mean 469.2 µm); and length/width ratio, 1.2 to 1.8 (mean 1.5). Second-stage juvenile (J2) (n=21) body length ranged from 400 to 485 µm (mean 437.1 µm); stylet length was 25 µm (no variation) with forwardly-directed knobs; conical tail with rounded tip ranged from 37.5 to 55.0 µm long (mean 46.6 µm) with hyaline region from 20.0 to 32.5 µm (mean 27.3 µm); and lateral field presented four incisures. These morphometrics were used to identify H. schachtii according to Subbotin et al. Confirmation of identification was by amplification and sequencing of a 28S rDNA gene fragment from individual females (GenBank Accession No. JQ040526). This is the first confirmed report of H. schachtii in North Dakota. SBCN was not detected in North Dakota in a 2001 survey of the principal sugar beet production area of the Red River Valley. Because there is extensive canola production across the northern part of the state bordering western and eastern sugar beet production areas, canola may serve as a bridge for movement of SBCN from west to east. Damage due to SBCN is well known in sugar beet, but there has been limited research on the effects of SBCN on canola. Reduction of B. napus growth by SBCN was reported. SBCN is a potential threat to these two important crops. |