Beet curly top resistance in USDA-ARS Kimberly germplasm lines, 2015

Curly top caused by Beet curly top virus is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. Host resistance is the primary defense against this problem, but resistance in commercial cultivars is only low to intermediate. In order to identify novel sources of curly top resistance, 14 sugar beet lines were screened in a disease nursery in 2015. The lines were arranged in a randomized complete block design with six replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the four-to six-leaf growth stage on 24 Jun. Foliar symptoms were evaluated on 13 and 20 Jul using a scale of 0-9 (0 = healthy and 9 = dead) in a continuous manner. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was moderately severe with good symptom development in the susceptible check. Based on the overall visual rating, KDH13 and KDH4-9 performed the same as the resistant check and were better than all other entries. Additionally, ELISA data also indicated that these two lines had significantly lower virus titer than all other entries including the resistant check. These germplasm lines will be released to the general public, so they can be utilized to improve resistance in commercial cultivars

Controlling severe curly top in sugarbeet

Controlling curly top in sugarbeet has been industry priority in the western United States since the 1920s. Curly top is a virus disease that is vectored by the beet leafhopper. If the beet leafhopper moves into commercial fields early in the season, virus is more likely to be transmitted to sugarbeet plants at an early growth stage. However, the plants are more susceptible to the virus at early growth stages. Thus even if the plants contain host resistance, they sustain considerable damage if infected at an early growth stage. In order to supplement host resistance insecticide seed treatments were investigated previously and proven to be effective under low to moderate disease pressure. In the current study under high disease pressure (6 viruliferous beet leafhoppers per plant), the neonicotinoid insecticide seed treatments (clothianidin and thiamethoxam) performed well. Thus the neonicotinoid seed treatments would appear to be a good supplement to host resistance even under high disease pressure

Insecticide seed treatments for sugarbeet

Pest feeding and vectoring of viruses cause serious problems in sugarbeet production worldwide. In order to ameliorate pest and disease problems on sugarbeet, two seed treatments, Poncho Beta (60 g a.i. clothianidin + 8 g a.i. beta-cyfluthrin/100,000 seed) and Cruiser Tef (60 g a.i. thiamethoxam + 8 g a.i. tefluthrin/100,000 seed) were investigated (the neonicotinoid was tested alone in some trials). The two seed treatments and an untreated check were tested in a series of eight field trials from 2006 to 2008 along with various commercial sugarbeet cultivars in a randomized complete block design with eight replications per trial. Natural pest incidence and curly top symptoms were evaluated. Both Poncho Beta and Cruiser Tef provided significant reduction in curly top symptoms and incidence of spinach leafminer (Pegomya hyoscyami Panzer), black bean aphid (Aphis fabae Scopoli), and sugarbeet root aphid (Pemphigus betae Doane). At times Poncho Beta performed better than Cruiser Tef, but yield parameters for the two products were similar. When averaged over the trials, Poncho Beta improved yields over the untreated check by 3.3 t/A, a 9% increase. Neonicotinoid seed treatments will play an important role in disease and pest management in sugarbeet production, but should be viewed as a supplement to host resistance and not a substitute for it

Experimental Sugar Beet Cultivars Evaluated for Rhizomania Resistance and Storability in Idaho, 2009

Thirty-four experimental sugar beet cultivars and five commercial check cultivars were evaluated in a commercial sprinkler-irrigated sugar beet field near Declo, ID where winter wheat was grown in 2008. The field trial relied on natural infection for rhizomania development. The plots were planted on 20 Apr 09 to a density of 142,560 seeds/A, and thinned to 47,520 plants/A on 8 Jun. Plots were four rows (22-in . row spacing) and 24 ft long. The experimental design was a randomized complete block design with four replications per cultivar. The crop was managed according to standard cultural practices. The plants were mechanically topped and the center two rows were collected with a mechanical harvester on 13 Oct. At harvest the roots were evaluated for rhizomania (Rz rating) using a scale of 0-9 (0 = healthy and 9 = dead). The percent sucrose at harvest was established based on two eight-root samples from each plot. The samples were submitted to the Amalgamated Tare Lab (determined percent sucrose, conductivity, nitrates, and tare). At harvest, eight roots per plot were also placed in a mesh onion bag, weighed, and placed in an indoor commercial sugar beet storage facility in Paul, ID on 14 Oct set to hold 35°F. On 18 Feb 10, the roots were evaluated for the percentage of surface area covered by fungal growth. On 22 Feb 10 roots were retrieved after 131 days in storage and evaluated for weight and percent sucrose (via gas chromatography). Only samples from the same plots were compared, when establishing percent reduction in sucrose at harvest versus storage. Data were analyzed using the general linear models rocedure (Proc GLM-SAS), and Fisher’s protected least significant difference was used for mean comparisons. Root rots and other disease problems other than rhizomania were not evident in the plot area. Rhizomania was uniform based on foliar symptoms, but root symptom development was minimal. Nevertheless, there were significant differences among cultivars for all variables, except fungal growth on the root surface in storage. B-101 was borderline for rhizomania resistance, since cultivars with ratings over 3.0 are considered susceptible. Root yield averaged 37 tons/A which was higher than Idaho’s average of 31 tons/A (USDA-National Ag. Stat. Service). Surface fungal growth ranged from 4 to 30% and surface root rot ranged from 1 to 20%, depending on cultivar. By the end of the storage season, weight loss ranged from 3.1 to 7.1% and sucrose losses ranged from 23 to 57%. Thus, improving storability in sugar beet cultivars to reduce sucrose losses could have considerable economic benefit

Commercial Sugar Beet Cultivars Evaluated for Rhizomania Resistance and Storability in Idaho, 2009

Rhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet cultivars with resistance to BNYVV and evaluate storability, 22 commercial cultivars were screened by growing them in a commercial sugar beet field naturally infested with BNYVV in Declo, ID during the 2009 growing season in a randomized complete block design with 4 replications. At harvest on 13 October 2009, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. Storage samples were evaluated for fungal growth known to correlate with sucrose loss. Depending on cultivar, surface fungal growth ranged from 5 to 42% by 18 February 2010. Overall, the commercial cultivars had an average sucrose reduction of 33% after 131 days in storage. Improving cultivar performance for resistance to sucrose loss in storage and rhizomania has the potential to lead to considerable economic benefit to the sugar beet industry

Response of BGMV and BGYMV resistant common bean to beet curly top virus

Crop losses can be severe when susceptible large-seeded Andean dry and green bean cultivars are planted early in dry areas with a history of curly top caused by Beet curly top virus (BCTV) and closely related species. In order to assess the level of curly top resistance in 65 diverse dry and green bean genotypes, seed was planted in a commercial field in Kimberly, ID in 2007. Viruliferous beet leafhoppers were released approximately 3 weeks after emergence to generate an artificial epiphytotic. Plants were rated on a scale of 1-5 (1 = healthy, 5 = highly susceptible) 5 weeks after infestation and verified at fully developed pod stage (R8). Capri and UI 51 were among the most susceptible genotypes, while A 429, DOR 390, DOR 500, and G 2402 did not exhibit any symptoms. In general, breeding lines and cultivars with known resistance to Bean golden mosaic virus and Bean golden yellow mosaic virus (except Morales) were resistant to moderately resistant to BCTV. Additional testing will be required to verify the resistance followed by research to determine the evolutionary origin of the genes for resistance to these viruses

Beet curly top resistance in USDA-ARS Kimberly germplasm lines, 2015

Curly top caused by Beet curly top virus is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. Host resistance is the primary defense against this problem, but resistance in commercial cultivars is only low to intermediate. In order to identify novel sources of curly top resistance, 14 sugar beet lines were screened in a disease nursery in 2015. The lines were arranged in a randomized complete block design with six replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the four-to six-leaf growth stage on 24 Jun. Foliar symptoms were evaluated on 13 and 20 Jul using a scale of 0-9 (0 = healthy and 9 = dead) in a continuous manner. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was moderately severe with good symptom development in the susceptible check. Based on the overall visual rating, KDH13 and KDH4-9 performed the same as the resistant check and were better than all other entries. Additionally, ELISA data also indicated that these two lines had significantly lower virus titer than all other entries including the resistant check. These germplasm lines will be released to the general public, so they can be utilized to improve resistance in commercial cultivars

Spirit of Christmas

Sermon regarding Christmas. Delivered at the University Church of Johnson C. Smith University on December 17, 1939

Controlling severe curly top in sugarbeet

Controlling curly top in sugarbeet has been industry priority in the western United States since the 1920s. Curly top is a virus disease that is vectored by the beet leafhopper. If the beet leafhopper moves into commercial fields early in the season, virus is more likely to be transmitted to sugarbeet plants at an early growth stage. However, the plants are more susceptible to the virus at early growth stages. Thus even if the plants contain host resistance, they sustain considerable damage if infected at an early growth stage. In order to supplement host resistance insecticide seed treatments were investigated previously and proven to be effective under low to moderate disease pressure. In the current study under high disease pressure (6 viruliferous beet leafhoppers per plant), the neonicotinoid insecticide seed treatments (clothianidin and thiamethoxam) performed well. Thus the neonicotinoid seed treatments would appear to be a good supplement to host resistance even under high disease pressure

Beet curly top virus strains associated with sugar beet in Idaho, Oregon, and a Western U.S. collection

Curly top of sugar beet is a serious, yield limiting disease in semi-arid production areas caused by Beet curly top virus (BCTV) and transmitted by the beet leafhopper. One of the primary means of control for BCTV in sugar beet is host resistance but effectiveness of resistance can vary among BCTV strains. Strain prevalence among BCTV populations was last investigated in Idaho and Oregon during a 2006-2007 survey, but changes in disease severity suggested a need for reevaluation. Therefore, 406 leaf samples symptomatic for curly top were collected from sugar beet plants in commercial sugar beet fields in Idaho and Oregon from 2012 to 2015. DNA was isolated and BCTV strain composition was investigated based on polymerase chain reaction (PCR) assays with strain specific primers for the Severe (Svr) and California/Logan (CA/Logan) strains and primers that amplified a group of Worland (Wor)-like strains. The 2006-2007 ID/OR BCTV positive sugar beet samples (59% had mixed infections) included: 87% Svr, 7% CA/Logan, and 60% Wor-like. The BCTV strain distribution in the new survey (16% had mixed infections) averaged 2% Svr, 30% CA/Logan, and 87% Wor-like. Whole genome sequencing (GenBank accessions KT276895 to KT276920 and KX867015 to KX867057) with overlapping primers, found that the Wor-like strains included Wor, Colorado (CO), and a previously undescribed strain designated Kimberly1 (Kim1). Results confirm a shift from Svr being one of the dominant BCTV strains in commercial sugar beet fields in 2006-2007 to becoming undetectable at times during recent years