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Controlling severe curly top in sugarbeet
Get PDFControlling 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
Water quality and surfactant effects on the water repellency of a sandy soil
Get PDFDifferences in irrigation water quality may affect the water repellency of soils treated or untreated with surfactants. Using simulated irrigations, we evaluated water quality and surfactant application rate effects upon the water repellency of a Quincy sand (Xeric Torripsamment). We used a split plot design with two irrigation water qualities, three surfactant application rates, two irrigations, and twelve sampling depths as fixed effects, with four replications. Each water quality x rate x irrigation combination was a main plot and depth was a repeated-measures subplot. A slightly water repellent Quincy soil (average water drop penetration time, WDPT, of 2.5 s) was packed in 25-mm lifts (or layers) to a bulk density of 1.6 Mg/cubic m into 0.15-m-high x 0.105-m-diameter plastic columns. We studied a nonionic surfactant, a blend of an ethylene oxide/propylene oxide block copolymer and an alkyl polyglycoside. We sprayed the surfactant at rates of 0, 9.4, and 46.8 L/ha, diluted with reverse osmosis water (RW) to apply 187 L/ha of solution, onto the soil surface of each packed column. About 24 h after surfactant application, columns were sprinkler irrigated with either RW or well water (WW) at 88 mm/h for 0.25 h without runoff. Well water (pH 7.6) contained 54.90 mg Ca/L, 67.16 mg Na/L, and had an electrical conductivity (EC) of 0.7 dS/m and sodium adsorption ratio (SAR) of 1.7. The RW (pH 5.7) contained 0.882 mg Ca/L, 3.201 mg Na/L, and had an EC of 0.0072 dS/m and SAR of 2.2. After the first irrigation with each water quality, half of the columns were destructively sampled in 12 increments to the 150-mm depth, with water content measured on a subsample and the remainder air-dried. Five days later, sample WDPT was measured. The remaining unsampled columns were oven dried at 30° C for three days to a mean soil water content < 0.04 g/g, cooled at ambient temperatures for 16 h, then irrigated with water of the same quality as before and sampled as previously. After the first irrigation, WDPT at depths from 97 to 117 mm averaged across surfactant rates reached a maximum of 28 s, regardless of irrigation water quality. WDPT was greatest at 117 mm with RW but only at 97 mm with WW. After the second irrigation, maximum WDPT was 1202 s at 139 mm with RW but only 161 s at 117 mm with WW, nearly 7.5 fold less than with RW. WDPT was greatest near the wetting front, irrespective of water quality. We conclude that irrigation water containing modest amounts of electrolytes or salts, in this case mostly salts of Ca and Na, reduces water repellency in the presence or absence of surfactant. Sprinkler irrigating this water-repellent soil translocated repellency-inducing moieties to the wetting front, concentrating them there in either surfactant-treated or untreated soils. Repeated irrigations further concentrated and drove repellency-inducing moieties deeper. When the sprinkler water contained modest amounts of electrolytes, the repellency at the wetting front was reduced nearly an order of magnitude. It appears that irrigating water-repellent soils using water containing electrolytes (probably Ca salts), greatly reduces repellency in the zone where hydrophobic substances accumulate in such soils. In our study, this occurred whether or not the soil was pretreated with surfactant. The results suggest that farmers and managers of turf and other agricultural land may be able to control the soil depth where repellency-inducing substances accumulate. For turf managers, this depth should be well below that of rooting. For farmers, it should be below the depth of rooting or below the depth of annual tillage, whichever is greater. Our experimental results may also help explain erratic surfactant performance under rainfed conditions where neither water quality nor depth of infiltration can be fully controlled
Rhizoctonia-Bacterial Root Rot Complex in Sugarbeet
Get PDFThe Rhizoctonia-bacterial root rot complex is a disease problem of concern worldwide in sugarbeet. A series of studies have been conducted which indicate that the complex is initiated by the fungal pathogen, Rhizoctonia solani. However, only about 6% of the root mass is lost to the fungal infection and 68-71% of the root mass is lost to subsequent bacterial rot. The bacterial rot phase of the problem was proven to be initiated by Leuconostoc. Field studies show that if Rhizoctonia root rot is limited then the bacterial rot phase will be limited as well. Until we develop a better understanding of this rot complex, control efforts should target Rhizoctonia, since Leuconostoc is naturally widespread in the environment. Preliminary evidence suggests that sugarbeet cultivars will be resistant to the strains of Rhizoctonia found in Idaho if they contain the FC709-2 source of resistance
Beet curly top resistance of USDA-ARS National Plant Germplasm System Plant Introductions, 2010
Get PDFTwenty-six wild beet (Beta vulgaris subsp. maritima (L.) Arcang) accessions from the Beta collection of the USDA-ARS National Plant Germplasm System were screened for resistance to Beet severe curly top virus (BSCTV) and other closely related Curtovirus species in 2010. The curly top evaluation was conducted at the USDA-ARS North Farm in Kimberly, ID which had been in beans in 2009. The field was disked in the spring, fertilized (160 lb P2O5/A) on 7 Apr 09, sprayed with Ethotron (2 pt/A), and roller harrowed. The germplasm was planted (density of 142,560 seeds/A) on 18 May. The plots were two rows 10 ft long with 22-in row spacing and arranged in a randomized complete block design with two replications. A resistant breeding line from Betaseed, Inc., G6040, was included as a resistant check. The fields were sprinkler irrigated and hand weeded as necessary. Plant populations were thinned to about 47,500 plants/A on 19 Jun. Plants were inoculated at the four to six leaf growth stage on 23 Jun with six viruliferous beet leafhoppers per plant. The beet leafhoppers were moved twice a day (right after sunrise and just before sunset) for one week by dragging a tarp through the field. The plants were sprayed with Lorsban 4E (1.5 pints/A) on 7 Jul to kill the beet leafhoppers. The plots were rated for foliar symptom development on 15 Jul using a scale of 0-9 (0 = healthy with no sign of disease and 9 = leaves necrotic and plant dead; Mumford, D.L. 1974. Procedure for inducing curly top epidemics in field plots. J. Am. Soc. Sugar Beet Technol. 18:20-23), with disease index (DI) treated as a continuous variable. Data were analyzed using the general linear models procedure (Proc GLM-SAS), and Fisher’s protected least significant difference was used for mean comparisons.
Curly top development was uniform and other disease problems were not evident in the plot area. The PIs were a combination of annual and biennial plant types. The resistant check was not significantly more resistant than any of the 19 lowest rated lines (i.e. most resistant), which ranged from having a DI of 5.0 to having a DI of 6.0. The resistant germplasm were from a number of European countries. With the narrow range of scores (4.95 to 7.25), it will be necessary to evaluate these germplasm once more at a future date
Residual Effects of Fresh and Composted Dairy Manure Applications on Potato Production
Get PDFPotato growers in Idaho and other dairy producing regions often grow potatoes on fields that have had a history of fresh and composted manure applications. Growers remain uncertain of the impacts that previous manure applications will have on tuber yield and quality, as well as diseases, physiological disorders, and contamination by human pathogenic bacteria such as E. coli. The focus of this study was to determine the long term effects of manure, compost, and chemical phosphorus (P) fertilizer applications on tuber yields, tuber quality, nutrient uptake, tuber disorders and diseases, and soil nutrient concentrations. Russet Burbank potatoes were grown in 2008 and 2009 on plots that had received dairy manure, dairy compost, P fertilizer, or no P source (control) at the same target P rate in 2003, 2004, and 2005. Compared with the P fertilizer treatment, applications of manure and/or compost significantly increased total yields, soil potassium (K), soil nitrate (NO3-N), early season petiole P, and late season petiole K in at least one year of the two-year study. There were no significant differences between P fertilizer, manure, and compost treatments on soil test P, late season petiole P, early season petiole K, E. coli populations on tuber surfaces, common tuber diseases and disorders, and tuber quality. Based on our findings, tuber yields significantly increased three years after applications of fresh and composted dairy manure, while tuber diseases, disorders, and quality were not affected
Clinoptilolite Zeolite Influence on Nitrogen in a Manure-Amended Sandy Agricultural Soil
Get PDFDevelopment of best management practices can help improve inorganic nitrogen (N) availability to plants and reduce nitrate-nitrogen (NO3-N) leaching in soils. This study was conducted to determine the influence of the zeolite mineral clinoptilolite (CL) additions on NO3-N and ammonium-nitrogen (NH4-N) in two common Pacific Northwest soils. The effects of CL application rate (up to 26.9 Mg ha-1) either band applied or mixed with a set rate of N fertilizer on masses of NO3-N and NH4-N in leachate and soil were investigated in a column study using a Portneuf silt loam (coarse-silty mixed mesic Durixerollic Caliciorthid) and a Wolverine sand (Mixed, frigid Xeric Torripsamment). All treatments for each soil received a uniform application of N from urea fertilizer, with fertilizer banded or mixed with CL. In the Portneuf soil, band application of CL and N contained 109% more total inorganic N (NO3-N + NH4-N) in the soil/leachate system compared with mixing. In both soils, CL application rate influenced the quantity of NO3-N and NH4-N in the leachate and soil. Application of CL at rates of 6.7 to 13.4 Mg ha-1 resulted in the conservation of inorganic N in the soils. Band applying CL and N seems to conserve available inorganic N in the soil compared with mixing CL and N possibly because of decreased rates of microbial immobilization, nitrification, and denitrification
Biochars impact on soil moisture storage in an Ultisol and two Aridisols
Get PDFExcessive copper concentrations in water systems can negatively impact biological systems. Because copper can form strong associations with organic functional groups, we examined the ability of biochar (a carbon-enriched organic bioenergy by-product) to sorb copper from solution. In a batch experiment, potassium hydroxide-steam activated pecan shell biochar was shaken for 24 hours in pH 6, 7, 8, or 9 buffered solutions containing various copper concentrations to identify effect of pH on biochar copper sorption. Afterwards, all biochar solids from the 24 hours shaking period were air-dried and then analyzed using X-ray absorption fine structure spectroscopy to determine solid-phase copper speciation. In a separate batch experiment, biochar was shaken for 30 days in pH 6 buffered solution containing increasing copper concentrations; the copper sorption maximum was calculated based on the exponential rise to a maximum equation. Biochar sorbed increasing amounts of copper as the solution pH decreased from 9 to 6. The X-ray absorption fine structure results revealed that copper was predominantly sorbed onto a biochar organic phase at pH 6 in a molecular structure similar to copper adsorbed on humic acid. The X-ray absorption fine structure spectra at pH 7, 8, and 9 suggested that copper was associated with the biochar as three phases: 1) a complex adsorbed on organic ligands similar to copper on humic acid; 2) carbonate phases similar to azurite; and 3) a copper oxide phase like tenorite. The exponential rise equation fit to the incubated samples predicted a copper sorption maximum of 42,300 mg/kg copper. The results showed that potassium hydroxide-steam activated pecan shell biochar could be utilized as a material for sorbing excess copper from water systems, potentially reducing the negative effects of copper in the environment
Biochar Usage: Pros and Cons
Get PDFSoil fertility benefits of charcoal application have been reported as early as 1847 indicating that plant nutrients are sorbed within charcoal pores. The use of biomass-derived black carbon or biochar, the solid byproduct from the pyrolysis processing of any organic feedstock, has garnered recent attention as a potential vehicle for carbon sequestration and a beneficial soil conditioner. However, most of the past biochar research has focused on improving the physico-chemical properties of tropical (i.e. terra preta) and highly weathered soils, while little research has focused on improving arid or semi-arid soils of the USA. Here, we present an overview of the potential benefits and drawbacks of biochar usage in western US agro-ecosystems based on research performed at multiple USDA-Agricultural Research Service locations (Washington, Idaho, Minnesota, and South Carolina)
Ambient Endotoxin Concentrations and Assessment of Offsite Transport at Open-Lot and Open-Freestall Dairies
Get PDFEndotoxins are derived from gram-negative bacteria and are a potent inducer of inflammatory reactions in the respiratory tract when inhaled. To assess daily fluctuations of airborne endotoxin and their potential for transport from dairies, endotoxin concentrations were monitored over an 8-h period at upwind (background) and downwind (5 m from edge of dairy) locations on three separate days at two dairies. The dairies consisted of an open-lot or an open-freestall production system, both of which were stocked with 10,000 milking cows. Upwind concentrations were stable throughout the sampling period, averaging between 1.2 and 36.8 endotoxin units (EU) m-3, whereas downwind concentration averages ranged from 179 to 989 EU-3. Downwind endotoxin concentrations increased with wind speed, animal activity, and lot management practices, resulting in concentrations up to 136-fold higher than upwind concentrations. An area-source model was used to predict downwind ground-level endotoxin concentrations at distances up to 2000 m from the production facilities.
Predicted concentrations decreased with distance and reached background levels within 500 to 2000 m, depending on the source emission rate and meteorological conditions
Nitrogen Use Efficiency of Irrigated Corn for Three Cropping Systems in Nebraska
Get PDFNitrogen use efficiency (NUE) is of economic and environmental importance. Components of NUE were evaluated in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska with different N rates and where the previous crop was either corn (CC), drybean
(Phaseolus vulgaris L.) (CD), or soybean (Glycine max L.) (CS). The mean grain yield with adequate nutrient availability was 14.7 Mg ha–1 . When no N was applied, measured soil properties and irrigation water N accounted for <20% of the variation in plant N
uptake (UN). Mean fertilizer N recovery in above-ground biomass was 74% at the lowest N rate compared with 40% at the highest N rate, a mean of 64% at the economically optimal N rate (EONR), and least with CD. Agronomic efficiency of fertilizer N averaged
29 kg grain kg-1 N at EONR and was also least with CD. Partial factor productivity of N averaged 100 kg grain kg-1 N at EONR, and was greater with CS compared with CC and CD. After harvest, residual soil nitrate-N (RSN) in the 0 to 1.2 m depth ranged from 21 to 121 kg ha-1 and increased with N rate. Mean RSN was 88, 59, and 59 kg ha-1 for CD, CC, and CS, respectively. High corn yields can be achieved with high NUE and low RSN by management to maximize profitability in consideration of yield potential, and by applying N at the right amount and time