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Foliar insecticides for the control of curly top in Idaho sugar beet, 2020
Full text linkCurly top caused by Beet curly top virus (BCTV) 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. The neonicotionoid seed treatments currently supplement this resistance to provide early season control. In order to identify other management options seven foliar insecticides were screened in 2019 on a commercial sugar beet cultivar approved for production. The plots were arranged in a randomized complete block design with eight replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the eight-leaf growth stage on 18 June. Foliar symptoms were evaluated on 10 August and 10 September 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 severe with good symptom development in the non-treated checks. Based on visual ratings, root yield, and estimated recoverable sucrose, the insecticide Venom and the Asana check were the only foliar treatment that provided some control of curly top. The yields for all treatments except the insecticide seed treatment check, the Asana foliar check, and the Venom treatment indicate that the cultivar was severely infected during the study. These data show that sugar beet production in areas with curly top would likely suffer considerably without the neonicotinoid seed treatments and the supplemental foliar treatments
Changes in bacterial endophyte community following aspergillus flavus infection in resistant and susceptible maize kernels
Full text linkAspergillus flavus (A. flavus) mediated aflatoxin contamination in maize is a major global economic and health concern. As A. flavus is an opportunistic seed pathogen, identification of factors contributing to kernel resistance will be of great importance in the development of novel mitigation strategies. Using V3–V4 bacterial rRNA sequencing and seeds of A. flavus resistant maize breeding lines TZAR102 and MI82 and a susceptible line, SC212, we investigated kernel specific changes of bacterial endophytes during infection. A total of 81 bacterial genera belonging to 10 phyla were detected. Bacteria belonging to the phylum Tenericutes comprised 86-99% of detected phyla followed by Proteobacteria (14%), and others (<5%) that changed with treatments and/or genotypes. Higher basal levels (without infection) of Streptomyces, and Microbacterium and increases in the abundance of Stenotrophomonas and Sphingomonas in the resistant lines following infection may suggest their role in resistance. Functional profiling of bacteria using 16S rRNA sequencing data revealed the presence of bacteria associated with the production of putative antifungal type II polyketides, sesquiterpenoids in the resistant vs. susceptible lines. Future characterization of endophytes predicted to possess antifungal/ anti-aflatoxigenic properties will aid in their development as effective biocontrol agents or microbiome markers for maize aflatoxin resistance
Fertilizer nitrogen recovery of irrigated spring malt barley
Full text linkWell defined nitrogen (N) management in irrigated two-row malting barley (Hordeum vulgare L.) is critical for yield, quality, and to minimize negative environmental impacts. Data on fertilizer N recovery efficiency (FNRE) and the fate of fertilizer-N in the soil is lacking for irrigated malting barley. The objective of this study was to determine uptake and partitioning of 15N labeled urea in the plant and soil. Mimicking common regional practices, urea was either surface applied or incorporated at a total N rate of 214 kg N ha-1 at planting. Three common malt cultivars were grown, and samples were collected four times during the growing season (Feekes growth stages 4/5, 10.0, 11.2, and 11.4). Barley plants at Feekes 11.2 and 11.4 were separated into plant (culms plus leaves) and spikes. Plant N accumulation was lowest at Feekes 4/5 and increased to a maximum at Feekes 11.2 where FNRE was greatest at Feekes 10.0. Nitrogen was redistributed from the plant to the spike from Feekes 11.2 to 11.4. The barley plant FNRE averaged 43% at maturity. The total soil-plant FNRE for the surface application was 66%, which was less than the incorporated fertilizer FNRE of 77%. Results from the current study provide evidence of the increased FNRE of incorporated applications in high-input barley production systems as well as similar recovery efficiency as compared to previous work under higher-yielding conditions. Results can be used to refine growing practices to ensure agronomically and environmentally sound management
Beet curly top resistance in USDA-ARS Kimberly germplasm, 2020
Full text linkCurly top caused by Beet curly top virus (BCTV) 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, 8 sugar beet lines produced by the USDA-ARS Kimberly sugar beet program were screened in a disease nursery in 2020. 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 23 Jun. Foliar symptoms were evaluated on 13 July 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 checks. Based on the visual rating, one line (KDH39/KDH13; population from selected F4 families) and one genetic stock line (KDH13) were not significantly different from the resistant checks. The resistant KDH39/KDH13 line will be suitable for single trait selection and advancement to breeding lines to enrich the BCTV resistance gene pool in the USDA-ARS sugar beet germplasm
Ammonia volatilization from fertilizer sources on a loam soil in Idaho
Full text linkOptimizing crop nitrogen (N) uptake while minimizing ammonia (NH3) volatilization from N-fertilizer sources is a critical part of agricultural best management practices. Urea is the most widely used N-fertilizer but also one of the most susceptible to losses as NH3. Fertilizer source and additives can be used to reduce NH3 volatilization. Specifically, urease inhibitors e.g., N-(n-butyl) thiophosphoric triamide (NBPT) can reduce NH3 volatilization from urea. Novel fused ammonium sulfate nitrate (ASN) products have recently been developed as another potential alternative N-fertilizer source but have not been studied widely. A field study was performed to quantify NH3 volatilization from the newly available ASN fertilizer as compared to various N-fertilizers (ammonium sulfate (AS) and urea) including urea treated with the urease inhibitor NBPT in an alkaline calcareous loam soil in Idaho. Further, we assessed NH3 volatilization from surface applied and incorporated N-fertilizers from these various N sources. Untreated surface-applied urea volatilized the highest amount of NH3, whereas incorporation of N-fertilizers was effective in reducing volatilization as compared to untreated surface applied urea. Our study indicated that the N-fertilizer sources (AS, ASN, and Urea-NBPT) were equally effective in reducing NH3 volatilization when compared to surface applied urea. Our study will help refine N-fertilize management under multiple field situations and traditional management practices of crop producers in the western United States. Further, site-years and study locations would be needed to provide evidence of the effectiveness of ASN in reducing NH3 volatilization under a wider range of soil and environmental conditions
Impact of water and nitrogen availability on maize evapotranspiration and soil water trends under high frequency sprinkler irrigation
Full text linkOne potential advantage of variable rate irrigation (VRI) is that less water can be applied to field areas with low productivity, without adversely affecting yield, thereby reducing water use, nutrient leaching, and pumping costs. This inferred potential advantage of VRI has not been fully evaluated experimentally. A three-year field study on maize (Zea mays L.) was conducted to test the hypothesis that high and low productivity has no effect on crop ET. High and low productivity were established using high and low soil N supplies. The effect of 0 and 246 kg ha-1 of nitrogen (N) application under fully irrigated (FIT) and three limited irrigation rates (75% FIT, 50% FIT, and 25 FIT) on maize yield and soil water trends were investigated in 2017, 2018 and 2019 under lateral-move irrigation in south central Idaho. Maize ET, grain yield and soil water contents were significantly different (p < 0.05) between irrigation treatments and study year. Grain yield decreased nonlinearly as seasonal irrigation amount decreased regardless of N supply. The maize ET and soil water contents from the two N rates within each irrigation level were the same. During each year of the study and within each irrigation treatment, there were no significant (p < 0.05) maize ET or soil water content differences between the N treatments. Assuming yields under different N application rates were representative of high and low maize productivity areas of a field, the results show that reducing water application to low productivity areas will reduce grain yield at the same rate as in high productivity areas. Thus, VRI does not provide the opportunity to reduce water use and pumping costs while maintaining yield levels in low production areas
Kimberly sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2020
Full text linkRhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet germplasm lines with resistance to BNYVV and storage rots, eight Beta vulgaris lines and five check cultivars were screened. The lines were grown in a sugar beet field infested with BNYVV during the 2020 growing season in a randomized complete block design with 6 replications. At harvest on 13-14 October, roots were dug and evaluated for rhizomania symptoms and then placed in an indoor commercial sugar beet storage building. After 131 days in storage, samples were evaluated for the percentage of root surface area covered by fungal growth or rot. Rhizomania symptom development in the field was uniform and other disease problems were not evident in the plot area. The BNYVV susceptible sugar and red beet checks both had 100% foliar symptoms and a high root disease severity ratings. The resistant check with two resistance genes, Rz1 + Rz2 (check 3), had 1% foliar symptoms and low root rating. The resistant checks with only one resistance gene had foliar symptoms ranging from 8 to 13%, but their root ratings were still within an acceptable range. Foliar symptoms indicate single gene resistance for BNYVV is becoming marginal. Based on the root ratings, all entries had some level of BNYVV resistance since they were all better than the susceptible checks. However, only entry 9 had a root rating similar to the resistant checks and the yellowish leaves (100% foliar rating) were likely an indication of nutrient deficiency and not RZ susceptibility. Four entries (1, 4, 9, and 10) had resistance to fungal rots in storage. Entry 1 has also had no foliar symptoms and a good storage rating in two previous evaluations. Entry 4 should be evaluated again next year since it had no foliar symptoms and a good storage rating. Some entries may serve as a starting point for identifying additional sources of resistance to BNYVV and storage rots
Ft. Collins sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2020
Full text linkThirty sugar beet (Beta vulgaris L.) lines from the USDA-ARS Ft. Collins sugar beet program and five check cultivars were screened for resistance to Beet necrotic yellow vein virus (BNYVV), the causal agent of rhizomania, and to storage rot. The rhizomania evaluation was conducted at the USDA-ARS North Farm in Kimberly, ID which has Portneuf silt loam soil and had been in barley in 2019. In the spring the field was plowed and fertilized (110 lb N and 120 lb P2O5/A) and roller harrowed on 27 Mar 20. The germplasm was planted (density of 51,840 seeds/A) on 20 Apr. The plots were one row 10-ft long with 22-in. between-row spacing and arranged in a randomized complete block design with 6 replicates. The crop was managed according to standard cultural practices for southern Idaho. The trial relied on endemic field inoculum for rhizomania and storage rot development. The plots were rated for rhizomania foliar symptom (percentage of plants with yellow, stunted, upright leaves) development on 24 Aug. The plants were mechanically topped and hand harvested on 13-14 Oct. At harvest, ten roots per plot were rated for rhizomania symptom development using a scale of 0 to 9 (0 = healthy and 9 = dead; Plant Disease 93:632-638), with disease index (DI) treated as a continuous variable. At harvest, eight roots per plot were also placed in a mesh-onion bag and kept in an indoor commercial storage facility (temperature set point 34°F) in Paul, ID on 15 Oct. On 22 Feb 21, after 131 days in storage, the roots were evaluated for the percentage of root surface area covered by fungal growth or rot. Data were analyzed in SAS (Ver. 9.4) using the general linear model (Proc GLM) procedure, and Fisher’s protected least significant difference (a = 0.05) was used for mean comparisons. The root ratings were rank transformed prior to analysis, but the non-transformed means have been presented in the table.
Rhizomania symptom development was uniform and other disease problems were not evident in the plot area. The BNYVV susceptible check plots (Check 1 and Red beet) had 100% foliar symptoms and high root disease ratings. Resistant check 3 had 1% foliar symptoms and a low root rating which indicates that resistance based on two genes is holding up. Single gene resistance (Checks 2 and 4) had foliar ratings ranging from 8 to 13% indicating single gene resistance is not completely effective, but the root ratings were still good. Three entries (13, 19, and 25) had a level of BNYVV resistance similar to resistant check 3 based on both foliar and root ratings. A number of the entries had resistance to fungal rots in storage, but only entries 13 and 19 performed well for all three variables. Some entries may serve as a starting point for identifying additional sources of resistance to BNYVV and storage rots
Cycling phosphorus and nitrogen through cropping systems in an intensive dairy production region
Full text linkAs pressure on the dairy industry to reduce its environmental impact increases, efficient recycling of manure nutrients through local cropping systems becomes crucial. The aim of this study was to calculate annual nitrogen (N) and phosphorus (P) budgets in six counties located in the Magic Valley, Idaho and estimate what distance manure would need to be transported to be in balance with crop nutrient demand given current dairy cattle populations and cropping systems. Our analysis suggests that crop N needs will not be met solely by manure, and synthetic fertilizer will need to be applied. However, to balance P with crop production, manure would need to be transported a minimum of 12.9 km from dairies and would have to replace synthetic fertilizer P on 91% of regional cropland. Education of producers and technical specialists would be necessary to improve the management of manure use in regional cropping systems. Technical solutions such as alternative diets for cattle and nutrient capture from manure streams will also likely be necessary to bring regional P into balance to protect environmental quality and improve the sustainability of the regional dairy industry
Commercial sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2019
Full text linkRhizomania 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, 37 commercial cultivars were screened by growing them in a sugar beet field infested with BNYVV in Kimberly, ID during the 2019 growing season in a randomized complete block design with 6 replications. At harvest on 7-8 October 2019, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. After 145 days in storage, samples were evaluated for surface rot, weight loss, and sucrose loss. Surface root rot ranged from 10 to 68%, weight loss ranged from 14 to 25%, sucrose losses ranged from 22 to 72%, and estimated recoverable sucrose ranged from 2,442 to 9,769 lb/A. Given these response ranges, selecting cultivars for rhizomania resistance and combining this resistance with storability will lead to considerable economic benefit for the sugar beet industry