Ionized Reflection Spectra from Accretion Disks Illuminated by X-Ray Pulsars

X-ray reflection signatures are observed around multiple classes of accreting compact objects. Modelling these features yield important constraints on the physics of accretion disks, motivating the development of X-ray reflection models appropriate for a variety of systems and illumination conditions. Here, constant density ionized X-ray reflection models are presented for a disk irradiated with a very hard power-law X-ray spectrum (\Gamma \u3c 1) and a variable high-energy cutoff. These models are then applied to the Suzaku data of the accreting X-ray pulsar LMC X-4, where very good fits are obtained with a highly ionized reflector responsible for both the broad Fe K line and the soft excess. The ionized reflector shows strong evidence for significant Doppler broadening and is redshifted by ~10^4 km/s. These features indicate that the reflecting material is associated with the complex dynamics occurring at the inner region of the magnetically-truncated accretion disk. Thus, reflection studies of X-ray pulsar spectra may give important insights into the accretion physics at the magnetospheric radius

Foliar and seed treatment insecticides for the control of beet curly top in Idaho sugar beet, 2023

Curly 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 insecticide treatments were screened in 2023 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 12 June. Foliar symptoms were evaluated on 7 and 25 August using a scale of 0-9 (0 = healthy and 9 = dead). 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 check. The three treatments with the Poncho Beta seed treatment provided better control than the other treatments based on foliar ratings, root yield, and estimated recoverable sucrose (ERS). Combining Methyl Jasmonate and Jasmonic Acid foliar treatments with the Poncho Beta seed treatment led to the best root yield and ERS. The Asana foliar check had the next best foliar ratings, root yield, and ERS. All other treatments including the non-treated check were dead at the second foliar rating and had almost no yield or ERS. This data show that sugar beet production in areas with curly top would suffer greatly without the neonicotinoid seed treatments and supplemental foliar treatments. Additional evaluations will need to be conducted with other insecticides if alternatives to the neonicotinoid (Poncho Beta) chemical class are to be identified for curly top control

Evaluation of USDA-ARS sugar beet germplasm for resistance to rhizomania and storage rot in Idaho, 2022

Thirty 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 2021. In the spring the field was plowed and fertilized (110 lb N and 160 lb P2O5/A) and roller harrowed on 6 Apr 22. The germplasm was planted (density of 114,048 seeds/A) on 3 May. 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 15 Aug. The plants were mechanically topped and hand harvested on 11-12 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). 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 13 Oct. On 14 Mar 23, after 152 days in storage, the roots were evaluated for the percentage of root surface area covered by fungal growth or rot. Except for root ratings, data were analyzed in SAS (Ver. 9.4) using the general linear model (Proc GLM) procedure, and Fisher’s protected least significant difference (α = 0.05) was used for mean comparisons. The root ratings were analyzed in a nonparametric analysis as described by Shah and Madden (Phytopathology 94:33-43)

Foliar insecticides for the control of curly top in Idaho sugar beet, 2022

Curly 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 2022 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 15 June. Foliar symptoms were evaluated on 20 July and 15 August using a scale of 0-9 (0 = healthy and 9 = dead). 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 check. The Poncho Beta seed treatment provided better control than all other treatments based on curly top ratings, root yield, and estimated recoverable sucrose (ERS). The Actara, Asana, Transform, and Violacein treatments all reduced curly top ratings compared to the non-treated check, but the control was not adequate to avoid serious reductions in root yield and ERS. These data show that sugar beet production in areas with curly top would suffer greatly without the neonicotinoid seed treatments and supplemental foliar treatments. Additional evaluations will need to be conducted with other insecticides if alternatives to the neonicotinoid (Poncho Beta) chemical class are to be identified for curly top control

USDA-ARS Plant Introduction lines evaluated for rhizomania and storage rot resistance in Idaho, 2022

Thirty sugar beet (Beta vulgaris L.) USDA-ARS Plant Introduction (PI) lines 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 2021. In the spring the field was plowed and fertilized (110 lb N and 160 lb P2O5/A) and roller harrowed on 6 Apr 22. The germplasm was planted (density of 114,048 seeds/A) on 3 May. 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 15 Aug. The plants were mechanically topped and hand harvested on 11-12 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). 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 13 Oct. On 14 Mar 23, after 152 days in storage, the roots were evaluated for the percentage of root surface area covered by fungal growth or rot. Except for root ratings, data were analyzed in SAS (Ver. 9.4) using the general linear model (Proc GLM) procedure, and Fisher’s protected least significant difference (α = 0.05) was used for mean comparisons. The root ratings were analyzed in a nonparametric analysis as described by Shah and Madden (Phytopathology 94:33-43)

Kimberly sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2022

Rhizomania 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, seven Beta vulgaris lines and five check cultivars were screened. The lines were grown in a sugar beet field infested with BNYVV during the 2022 growing season in a randomized complete block design with 6 replications. At harvest on 12 October, roots were dug and evaluated for rhizomania symptoms and then placed in an indoor commercial sugar beet storage building. After 152 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 no foliar symptoms and low root rating. The resistant checks with only one resistance gene had foliar symptoms ranging from 0 to 8%, 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. Entry 3 (KEMS12; PI672570) had a level of BNYVV resistance similar to resistant checks based on both foliar and root ratings. Although entries 1, 2, 6, and 7 all had poor foliar ratings, their root ratings were better than those for the susceptible checks. Both entries 1 (KEMS09) and 3 were described as containing some rhizomania resistance in their release notes, but entry 1 appears to have lost some of its resistance, while entry 3 remains resistant. All the entries had some resistance to fungal rots in storage, but only entry 3 performed well for all three variables. Thus, some entries will serve as genetic sources for identifying additional resistance to BNYVV and storage rots, which will aid the sugar beet industry in improving sucrose yield and retention in commercial sugar beet cultivars

Seed Transmission of the \u3ci\u3eHigh Plains virus\u3c/i\u3e in Sweet Corn

The High Plains virus (HPV), which infects corn and other cereals, was first found in 1993 in the United States. Research was initiated in 1995 to investigate the potential for seed transmission of HPV. Sweet corn seeds of various cultivars harvested in 1994 to 1996 from 13 fields and research plots in southwestern Idaho, Colorado, and Nebraska were seeded in potting mix in the greenhouse. Leaf samples collected at the three- to six-leaf stage from both symptomatic and asymptomatic plants were tested by enzyme-linked immunosorbent assay (ELISA). Of the 46,600 seeds planted, 38,473 seedlings emerged, and three tested positive by ELISA, exhibited mosaic symptoms, and had the presence of HPV confirmed by an additional test. One of the positive plants was used for successful acquisition and transmission of HPV by the wheat curl mite to Westford barley. The other two plants were used to successfully transfer HPV to other corn plants by vascular puncture inoculation of seed. These results indicate that HPV can be seed transmitted at a very low frequency in sweet corn

Combined Omics Approaches Reveal Distinct Mechanisms of Resistance and/or Susceptibility in Sugar Beet Double Haploid Genotypes at Early Stages of Beet Curly Top Virus Infection

Sugar beet is highly susceptible to Beet curly top virus (BCTV) which significantly reduces yield and sugar production in the semi-arid growing regions worldwide. Sources of genetic resistance to BCTV is highly limited and primarily dependent upon seed treatment with neonicotinoids, the use of which is gradually being restricted. Through double haploid production and genetic selection, we have developed BCTV resistant breeding lines. Using BCTV resistant (R) [KDH13; Line 13, and KDH4-9; Line 4] and susceptible (S) [KDH19-17; Line 19] lines, beet leafhopper meditated natural infection, mRNA/sRNA sequencing, and metabolite analyses we demonstrate potential mechanisms of resistance against the virus. At early infection stages (2- and 6-days post inoculation), examples of differentially expressed genes highly up-regulated in the ‘R’ lines (vs. ‘S’) include EL10Ac5g10437 (inhibitor of trypsin and hageman factor), EL10Ac6g14635 (jasmonate induced protein), EL10Ac3g06016 (ribosome related), EL10Ac2g03119 (unknown) etc. Pathway enrichment analysis showed differentially expressed genes predominantly involved with peroxisome, amino acids metabolism, fatty acid degradation, amino/nucleotide sugar metabolism etc. Metabolite analysis revealed significantly higher amounts of isoflavonoid O-glycosides, flavonoid 8-C glycosides, triterpenoid, iridoid-O-glycosides in the leaves of the ‘R’ lines (vs. ‘S’). The data presented here suggest a combination of transcriptional regulation and production of antiviral metabolites might contribute to BCTV resistance. In addition, genome divergence among BCTV strains differentially affects the production of small non-coding RNAs (sncRNAs) and small peptides which may potentially affect pathogenicity and disease symptom development