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Disease notes - Bacterial root rot
Get PDFBacterial root rot initiated by lactic acid bacteria, particularly Leuconostoc, occurs every year in Idaho sugarbeet fields. Hot fall weather seems to make the problem worse. Although Leuconostoc initiates the rot, other bacteria and yeast frequently invade the tissue as well. The acetic acid bacteria, particularly Gluconobacter, are what give the rotted tissue a fermented vinegar-like smell. The bacteria gain entry into the root through wounds caused by rodents, growth cracks, and fungal lesions such as those associated with Rhizoctonia root rot. No definite management practices for bacterial root rot in sugarbeet have been established, but minimizing problems with rodents and fungal root rots would be advisable
Effect of composting on the fate of steroids in beef cattle manure
Get PDFIn this study, the fate of steroid hormones in beef cattle manure composting is evaluated. The fate of 16 steroids and metabolites was evaluated in composted manure from beef cattle administered growth promotants and from beef cattle with no steroid hormone implants. The fate of estrogens (primary detected as estrone), androgens, progesterone, and the fusarium metabolite and implant a-zearalanol were monitored in manure compost piles. First-order decay rates were calculated for steroid half-lives in compost and ranged from 8 days for androsterone to 69 days for 4-androsterone. Other steroid concentration data did not fit first-order decay models which may indicate that other microbial processes may result in steroid production or synthesis in composting systems. We demonstrate that composting is an effective strategy to remove steroid hormones from manure. Total steroid hormone removal in composted beef cattle manure ranged from 79-87%
Delayed sample filtration and storage effects on dissolved nutrients measured in agricultural runoff
Get PDFStandard water quality analysis methods recommend that sediment-laden runoff waters sampled to determine dissolved nutrient concentrations be filtered immediately after collection. Few research studies have examined the influence of delayed filtration on sample stability or nutrient loss assessments. Twenty eight runoff water volumes were collected from 3 irrigation furrows during a 12-h irrigation set. Four subsamples of each volume were obtained; 2 were filtered (45 µm) in the field and the other 2 were filtered 10 days later, with or without boric acid treatment (1 mL saturated H3BO3 solution per 100 mL sample). All samples were refrigerated at 4 deg. C. Dissolved reactive P (DRP), NO3-N, and NH4-N concentrations were measured in all filtered samples 10 and 107 days after collection. Samples filtered in the field and those with a 10-day delayed filtration had similar dissolved DRP, NO3-N, and NH4-N concentrations, whether or not boric acid was added. After 107 days storage: 1) measured NO3-N concentrations in delayed filtration samples were 3.7-times greater than that in field-filtered samples, regardless of boric acid addition; and 2) boric acid had stabilized DRP and NH4-N concentrations relative to field-filtered samples. When integrated across the entire irrigation, the mean NO3-N and DRP furrow stream concentration and runoff mass losses computed from runoff water samples were similar for field filtered and delayed-filtration/no-boric-acid treatments. However, when these same parameters were computed using delayed-filtration, extended-storage (107-d) sample results, both NO3-N (4.7x) and DRP (1.9x) were greater in magnitude. The field-filtered or 10-d delayed-filtration without boric acid treatments provided the best dissolved nutrient measurements for comparing agricultural management effects at the field edge; however, results suggest that an incubation-type test of field-edge runoff water may provide a more accurate estimate of field management effects on downstream dissolved nutrient loads and aquatic ecosystems
Addition of activated switchgrass biochar to an aridic subsoil increases microbial nitrogen cycling gene abundances
Get PDFIt has been demonstrated that soil amended with biochar, designed specifically for use as a soil conditioner, results in changes to the microbial populations that reside therein. These changes have been reflected in studies measuring variations in microbial activity, biomass, and community structure. Despite these studies, very few experiments have been performed examining microbial genes involved in nutrient cycling processes. Given the paucity of research in this area, we designed a six-month study in a Portneuf soil (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid) treated with three levels (1%, 2%, and 10% w/w ratio) of a biochar pyrolyzed from switchgrass (Panicum virgatum) at 350°C and steam activated at 800°C to measure the abundances of four genes involved in nitrogen (N) cycling. Gene abundances were measured using qPCR, with relative abundances of these genes calculated based on measurement of the 16S rDNA gene. At the end of the six-month study, all measured genes showed significantly greater abundances in biochar amended treatments as compared to the control, potentially increasing the amount of N cycled in soils receiving such treatments. In soil amended with 10% biochar, genes involved in nitrogen fixation (nifH), and denitrification (nirS), showed significantly increased relative abundances. Lastly, gene abundances and relative abundances correlated with soil characteristics, in particular nitrate nitrogen, % N and % carbon. In toto, these results confirm that activated switchgrass-derived biochar, designed for use as a soil conditioner, has an impact on the treated soils microbial communities. We therefore suggest that future use of biochar as a soil management practice should take into account not only changes to the soil's physiochemical properties, but its biological properties as well
Reducing nutrient losses in runoff from furrow irrigation
Get PDFFew studies have comprehensively examined nutrient losses in runoff from furrow-irrigated fields, but the rising cost of fertilizer and finite nature of the resource encourages further research. A 2-yr experiment measured runoff losses of sediment, particulate P and N, and dissolved NO3-N, NH4-N, K, and reactive P (DRP) from fertilized, manured, or non-amended fields. Average nutrient losses were substantial, including 15.6 lbs ac/yr dissolved N, P, and K and 73.6 lbs ac/yr particulate N and P. The cost or replacing these nutrients with inorganic fertilizers was not trivial, at $54.69 ac/yr. Relative to non-amended soil, manure increased dissolved K, NO3-N, and DRP in runoff by 2.1x, 1.5x, and 2.7x, respectively. Other experiments evaluated the influence of furrow management practices on runoff nutrient loads from soils amended with manure in late summer and irrigated in the fall or following spring. We measured sediment, dissolved NO3-N, NH4-N, DRP, and TP concentrations in irrigation furrow runoff. Delaying the first irrigation until spring or treating the fall irrigation with polyacrylamide (WSPAM) reduced runoff component losses by 80 to 100% relative to Fall-Controls. In the spring irrigation, moldboard plowing reduced runoff DRP mass losses by ~60% compared to rototill. The buried lateral furrow system decreased runoff mass losses for sediment, DOC, and TP by >80% relative to conventional irrigation. This research demonstrated that several management practices may be successfully employed to substantially reduce offsite nutrient transport during the first irrigation on furrow-irrigated, manure-amended fields
Rhizoctonia root rot resistance in commercial sugar beet cultivars in Twin Falls County, ID, 2012
Get PDFRhizoctonia root rot continues to be a concerning problem in sugar beet production areas. To investigate resistance to this disease in 26 experimental sugar beet cultivars, field studies were conducted with three Rhizoctonia solani AG-2-2 IIIB strains. Based on means for the 26 cultivars, surface rot ranged from 0 to 93% depending on the strain-cultivar combination. Both the number of dead plants and root surface area rotted resulted in significant (P < 0.0004) cultivar differences. Based on Spearman’s rank correlation coefficient, there was always a significant relationship (P < 0.0279) when comparing cultivar performance across all three strains regardless of disease variable. The three most resistant cultivars performed well against all strains and variables, but still had half the root surface area rotted. Additional efforts need to be made to get more resistance to this disease problem in commercial sugar beet cultivars
Beet curly top resistance in USDA-ARS Plant Introductions, 2012
Get PDFThirty sea beet (Beta vulgaris subsp. maritima (L.) Arcang) and beet (Beta vulgaris subsp. vulgaris L.) plant introduction (PI) 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 2012. Commercial cultivars Monohikari and HM PM90 and Betaseed, Inc. germplasm line G6040 were included as susceptible and resistant checks. The curly top evaluation was conducted at the USDA-ARS North Farm in Kimberly, ID which has Portneuf silt loam soil and had been in alfalfa in 2011. The field was plowed in the fall and in the spring, fertilized (90 lb N and 110 lb P2O5/A) on 16 Apr 12, sprayed with Ethotron (2 pt/A), and roller harrowed. The germplasm was planted (density of 142,560 seeds/A) on 21 May. The plots were two rows 10 ft long with 22-in row spacing and arranged in a randomized complete block design with three replications. 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 22 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 4 Jul to kill the beet leafhoppers. The plots were rated for foliar symptom development on 10 Jul using a scale of 0-9 (0 = healthy and 9 = dead; Mumford 1974), 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. Disease development was uniform and other disease problems were not evident in the plot area. The disease pressure in the test was severe with good disease development in the more susceptible lines. Most of the lines were not significantly different from the most resistant check. These accessions will be retested and, if the resistance is confirmed, entered into USDA-ARS breeding programs to enhance sugar beet germplasm with increased resistance to Beet severe curly top virus (BSCTV) and other closely related Curtovirus species. These data will be entered into the USDA-ARS, NPGS GRIN database (http://www.ars-grin.gov/npgs/index.html)
Transport of steroid hormones in the vadose zone after land application of beef cattle manure
Get PDFA variety of naturally occurring steroid hormones are regularly excreted by livestock, while additional steroid hormones have been used as growth promoters by the livestock industry. Depending on manure age and storage conditions, both groups of compounds are likely to be present during application to crops. Recent research suggests that some estrogens, androgens and progestagens in surface waters may originate from runoff after land application of livestock manure. Groundwater may also be impacted by livestock manure when used as a nutrient source to crops and may be indicated by excess nitrate in water. Few studies have been conducted to investigate the potential of steroid hormones contamination of groundwater. The objective of this study was to monitor leaching of steroid hormones and other compounds associated with livestock manure through the soil profile after land application of manure. The study was conducted near North Platte, Nebraska between April 2008 and July 2011 on a silt loam soil. Leachate was collected at the bottom of 2.4 meter deep monolithic percolation lysimeters to sample water leached beneath plots fertilized with manure. Soil samples were also collected from surrounding irrigated field plots. Treatments consisted of two manure handling procedures (stockpiling and composting) and a check receiving no manure application. Manure stored from a previous year’s cattle feeding pen study was sampled and analyzed for steroid hormone content. Manure was applied to the lysimeters and adjacent plot areas in April 2008 at a rate satisfying the nitrogen requirements of winter wheat planted in the fall of 2007 and 2008 followed by soybeans planted in the spring of 2010 and 2011. Leachate from the lysimeters and soil samples (down to 2.4 meter depth) from surrounding areas were collected periodically during the study. Laboratory analyses of manure, soil, and leachate samples used liquid chromatography tandem mass spectrometry to identify 17 steroid hormones and metabolites. Progesterone, estrone, beta-zearalenol and 4-androstenedione were detected at varying concentrations in both composted (1.6-8.4 nanograms per gram) and stockpiled (3.7-11.4 nanograms per gram) manure. Steroid hormones and related compounds were detected in only 5 percent of the leachate samples. The greatest detected concentration was 20 nanograms per liter of natural progesterone in a leachate sample from a lysimeter treated with stockpiled manure. Steroid hormones or metabolites were detected in 10 percent of the soil samples. Seventy four percent of the detections in the soil samples were in the top half (top 1.2 meter) of the sampled soil depth. 17beta-estradiol was detected the most in the soil samples (4 percent) with a maximum concentration of 4.3 nanograms per gram in a plot treated with composted manure. No synthetic steroids were detected in any of the soil or leachate samples. The low detection of steroid hormones in the soil and leachate samples suggests that, while some hormones may move through the soil, most are readily degraded or adsorbed after manure application. Additional research is required to more clearly identify the mechanisms that control the environmental fate and transport of steroid hormones through the soil
Increasing the quantitative credibility of open-path FT-IR spectroscopic data with focus on several properties of the background spectrum
Get PDFThe choice of the type of background spectrum affects the credibility of open-path Fourier transform infrared (OP/FT-IR) spectroscopic data, and consequently the quality of data analysis. We systematically investigated several properties of the background spectrum. The results show that a short-path background measured with the lowest amplifier gain could significantly reduce noise in the calculated absorbance spectrum, by at least 30% in our case. We demonstrated that by using a short-path background, data analysis is more resistant to interferences, such as wavenumber shift or resolution alteration that occurs as a consequence of hardware aging or misalignment. We also discussed a systematic error introduced into quantitative analyses by the short-path background, and developed a procedure to correct the error. With this correction approach, a short-path background measured five years ago was still found to be valid. By incorporating these findings into the protocol for quantitative analysis, we processed the measurements by two OP/FT-IR instruments set up side by side in the vicinity of a large dairy farm to monitor NH3, CH4 and N2O. The two sets of calculated concentrations showed high agreement with each other. The findings of our investigations are helpful to atmospheric monitoring practitioners of OP/FT-IR spectroscopy and could also be a reference for future amendment to the protocols outlined in the guidelines of the US Environmental Protection Agency (USEPA), the American Society for Testing and Materials (ASTM), and the European Committee for Standardization (ECS)
Ft. Collins sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2012
Get PDFRhizomania caused by the Beet necrotic yellow vein virus (BNYVV) is a worldwide problem that can lead to loss of tonnage and lower percent sucrose in the field. BNYVV can also reduce the storability of roots. To identify germplasm with resistance to these problems, 18 sugarbeet germplasm lines developed by the USDA-ARS Ft. Collins sugarbeet program and four check cultivars were screened in a field experiment arranged in a randomized complete block design with 6 replications. During the growing season plants were evaluated for foliar rhizomania symptoms. At harvest on 4 October 2012, roots were evaluated for rhizomania symptoms and then placed into an indoor commercial sugarbeet storage building in Paul, ID. Foliar symptoms ranged from 0% for resistant checks to 95% for the susceptible check, indicating good separation of germplasm for BNYVV resistance should have been possible in the field study. BNYVV root ratings ranged from a low of 19 for a resistant check to a high of 32 for one of the susceptible entries at harvest. Fungal growth on the root surface in storage ranged from a low of 12% for an entry with good storability to a high of 71% for the BNYVV susceptible check. Entries 11, 12, and 15 performed well for all variables. Incorporating better resistance to BNYVV and good storability into commercial sugarbeet cultivars should allow for increased yields in the field and improved recovery of sucrose from roots in storage