Showing papers on "Rust published in 2006"

Resistance in U.S. Wheat to Recent Eastern African Isolates of Puccinia graminis f. sp. tritici with Virulence to Resistance Gene Sr31

Abstract: The stem rust resistance gene Sr31 derived from rye has been used as an important source of stem rust resistance in many wheat cultivars worldwide. Isolates of Puccinia graminis f. sp. tritici with virulence to Sr31 were identified from Uganda in 1999. Stem rust susceptibility in wheat lines with Sr31 was observed in Kenya in 2003 and 2004. An isolate collected from Uganda in 1999 and an isolate collected from Kenya in 2004, identified to be race TTKS, were used in the rust evaluations. Selected cultivars and advanced breeding lines (450 in total) of wheat from the United States were tested against these two stem rust isolates. Resistance to race TTKS was detected in major classes of wheat with the following frequencies: 16% of hard red spring wheat, 48% of hard red winter wheat, and 27% of soft winter wheat. The genes that conferred resistance in the spring wheat have not been conclusively identified. Resistance in cultivar Ivan was likely due to Sr24. Resistance in hard red winter wheat was pos...

Characterization of genetic loci conferring adult plant resistance to leaf rust and stripe rust in spring wheat

Abstract: Leaf (brown) and stripe (yellow) rusts, caused by Puccinia triticina and Puccinia striiformis, respectively, are fungal diseases of wheat (Triticum aestivum) that cause significant yield losses ann...

Evaluation of Virulence of Phakopsora pachyrhizi and P. meibomiae Isolates

Abstract: Asian soybean rust (ASR), caused by Phakopsora pachyrhizi and recently discovered for the first time in continental United States, has been of concern to the U.S. agricultural industry for more than 30 years. Since little soybean rust resistance is known, and resistance is often difficult to detect or quantitate, we initiated a project to develop a better, more quantitative, method. The methodology determined the average numbers and diameters of uredinia in lesions that developed on leaves of inoculated plants 14 days after inoculation. It was used to compare virulence of P. pachyrhizi isolates from Asia and Australia and P. meibomiae from Puerto Rico and Brazil, collected as many as 30 years earlier, with isolates of P. pachyrhizi recently collected from Africa or South America. Susceptible reactions to P. pachyrhizi resulted in tan-colored lesions containing 1 to 14 uredinia varying greatly in size within individual lesions. In contrast, on these same genotypes at the same time of year, resistance to other P. pachyrhizi isolates was typified by 0 to 6 small uredinia in reddish-brown to dark-brown lesions. Using appropriate rust resistant and rust susceptible genotypes as standards, examination of uredinia 14 days after inoculation allowed quantitative comparisons of sporulation capacities, one measure of susceptibility or resistance to soybean rust. The study verified the presence and ability to detect all known major genes for resistance to soybean rust in the original sources of resistance. It demonstrated that soybean lines derived from the original PI sources, and presumed to possess the resistance genes, in actuality may lack the gene or express an intermediate reaction to the rust pathogen. We suggest that a determination of numbers and sizes of uredinia will detect both major gene and partial resistance to soybean rust.

Evaluation of seedling and adult plant resistance to leaf rust in European wheat cultivars: Leaf rust resistance in European wheat cultivars

Abstract: A set of 105 European wheat cultivars, comprising 68 cultivars with known seedling resistance genes and 37 cultivars that had not been tested previously, was tested for resistance to selected Australian pathotypes of P. triticina in seedling greenhouse tests and adult plant field tests. Only 4% of the cultivars were susceptible at all growth stages. Twelve cultivars lacked detectable seedling resistance to leaf rust, and among the remaining cultivars, 10 designated genes were present either singly or in combination. Lr13 was the most frequently detected gene, present in 67 cultivars, followed by the rye-derived gene Lr26, present in 19 cultivars. Other genes present were Lrl, Lr3a, Lr3ka, Lr10, Lrl4a, Lrl7b, Lr20 and Lr37. There was evidence for unidentified seedling resistance in addition to known resistance genes in 11 cultivars. Field tests with known pathotypes of P. triticina demonstrated that 57% of the cultivars carried adult plant resistance (APR) to P. triticina. The genetic identity of the APR is largely unknown. Genetic studies on selected cultivars with unidentified seedling resistances as well as all of those identified to carry APR are required to determine the number and inheritance of the genes involved, to determine their relationships with previously designated rust resistance genes, and to assess their potential value in breeding for resistance to leaf rust.

Distribution of pathotypes with regard to host cultivars in French wheat leaf rust populations.

Abstract: Isolates of wheat leaf rust collected from durum and bread wheat cultivars in France during 1999-2002 were analyzed for virulence on 18 Thatcher lines with single genes for leaf rust resistance (Lr genes). Sampling focused on the five most widely grown bread wheat cultivars (two susceptible and three resistant) to allow statistical comparison of diversity indexes between the cultivars. Leaf rust populations from durum and bread wheats were different. The diversity of the bread wheat leaf rust pathotypes, as measured by the Shannon index, ranged from 2.43 to 2.76 over the 4 years. Diversity for wheat leaf rust resistance was limited in the host since we postulated only seven seedling resistance genes in the 35 cultivars most widely grown during 1999-2002. Leaf rust populations were strongly differentiated for virulence within bread wheat cultivars, and diversity was higher on those that were resistant, mainly due to a more even distribution of virulence phenotypes than on susceptible cultivars. The pathogen population on the susceptible cv. Soissons was largely dominated by a single pathotype (073100), whereas all other pathotypes virulent on cv. Soissons either decreased in frequency or remained at a low frequency during the period studied. Several pathotypes including the most complex one were found only on resistant cultivars, even though most of them were virulent on the susceptible cv. Soissons. Specific interactions were necessary, but not always sufficient, to account for pathotype distribution and frequencies on the cultivars, suggesting that selection for virulence to host resistance genes is balanced by other selective forces including selection for aggressiveness.

Bioprospecting endophytic bacteria for biological control of coffee leaf rust

Abstract: Suppression of plant diseases due to the action of endophytic microorganisms has been demonstrated in several pathosystems. Experiments under controlled conditions involving endophytic bacteria isolated from leaves and branches of Coffea arabica L and Coffea robusta L were conducted with the objective of evaluating the inhibition of germination of Hemileia vastatrix Berk. & Br., race II, urediniospores and the control of coffee leaf rust development in tests with leaf discs, detached leaves, and on potted seedling of cv. Mundo Novo. The endophytic bacterial isolates tested proved to be effective in inhibiting urediniospore germination and/or rust development, with values above 50%, although the results obtained in urediniospore germination tests were inferior to the treatment with fungicide propiconazole. Endophytic isolates TG4-Ia, TF2-IIc, TF9-Ia, TG11-IIa, and TF7-IIa, demonstrated better coffee leaf rust control in leaf discs, detached leaves, and coffee plant tests. The endophytic isolates TG4-Ia and TF9-Ia were identified as Bacillus lentimorbus Dutky and Bacillus cereus Frank. & Frank., respectively. Some endophytic bacterial isolates were effective in controlling the coffee leaf rust, although some increased the severity of the disease. Even though a relatively small number of endophytic bacteria were tested, promising results were obtained regarding the efficiency of coffee leaf rust biocontrol. These selected agents appears to be an alternative for future replacement of chemical fungicide.

Characterization of corrosion products on steel surfaces

Abstract: Corrosion Protection Function and Breakdown Mechanism of Passive Films on Stainless Steels- Passivation Oxide Films and Rust Layers on Iron- Semiconductor Property of Passive Films and Corrosion Behavior of Fe-Cr Alloys- Mechanistic Study on Formation of Iron Hydroxides and Oxides with FT-IR and UV Photospectroscopy- Structural Characterization for a Complex System by Obtaining Middle-Range Ordering- Corrosion Mechanism of Iron from an X-ray Structural Viewpoint- Surface Analysis of Oxides and Corrosion Products Formed on Surfaces of Iron-based Alloys- Characterization of Rust Layers on a Plain-Carbon Steel and Weathering Steels Exposed to Industrial and Coastal Atmosphere for Years- Synchrotron Radiation Study on Structure of Atmospheric Corrosion Products Formed on Steel Surfaces- Analysis of Iron Rusts by X-ray Diffraction and X-ray Absorption Fine Structure Measurements- Various Scale Analyses to Create Functioning Corrosion Products- Moessbauer Spectroscopic Study on Rust Formed on Steel Surfaces

Innate Nonhost Immunity in Barley to Different Heterologous Rust Fungi Is Controlled by Sets of Resistance Genes with Different and Overlapping Specificities

Abstract: We developed an evolutionary relevant model system, barley-Puccinia [corrected] rust fungi, to study the inheritance and specificity of plant factors that determine to what extent innate nonhost immunity can be suppressed. A mapping population was developed from a cross between an experimental barley line (SusPtrit) [corrected] with exceptional susceptibility to several heterologous [corrected] (nonhost) rust fungi and regular, immune, cv. Vada [corrected] Seedlings were inoculated with five heterologous [corrected] and two homologous (host) species of rust fungi. Resistance segregated quantitatively for each of the rust fungi. In total, 18 chromosomal regions were implicated. For each rust species, a different set of genes was effective. Of the 18 chromosomal regions, 11 were significantly effective to only one rust species and 7 were effective to more than one rust species, implying genetic linkage or pleiotropy. One resistance (R) gene for hypersensitive resistance to Puccinia hordei-secalini was mapped, suggesting occasional contribution of R genes to nonhost resistance in barley. Quantitative trait loci (QTLs) with effects to multiple rust fungi did not tend to be particularly effective to rust species that were phylogenetically related, as determined from their internal transcribed spacer sequence. We suggest that the QTLs described here play a role as specific and quantitative recognition factors that are specifically negated by the rust to successfully suppress innate immunity.

Effect of Leaf Rust on Grain Yield and Yield Traits of Durum Wheats with Race-Specific and Slow-Rusting Resistance to Leaf Rust.

Abstract: Leaf rust, caused by Puccinia triticina, is an important disease of durum wheat (Triticum turgidum) in many countries. We compared the effectiveness of different types of resistance in International Maize and Wheat Improvement Center-derived durum wheat germ plasm for protecting grain yield and yield traits. In all, 10 durum wheat lines with race-specific resistance, 18 with slow-rusting resistance, and 2 susceptible were included in two yield loss trials sown on different planting dates in Mexico with and without fungicide protection under high disease pressure. Eight genotypes with race-specific resistance were immune to leaf rust. Durum wheat lines with slow-rusting resistance displayed a range of severity responses indicating phenotypic diversity. Mean yield losses for susceptible, race-specific, and slow-rusting genotypes were 51, 5, and 26%, respectively, in the normal sowing date trial and 71, 11, and 44% when sown late. Yield losses were associated mainly with a reduction in biomass, harvest index, and kernels per square meter. Slow-rusting durum wheat lines with low disease levels and low yield losses, as well as genotypes with low yield losses despite moderate disease levels, were identified. Such genotypes can be used for breeding durum wheat genotypes with higher levels of resistance and negligible yield losses by using strategies that previously have been shown to be successful in bread wheat.

Controle químico da ferrugem asiática da soja em função de ponta de pulverização e de volume de calda

Abstract: The spray nozzles are one of the most important components of pesticide hydraulic sprayers. This study aimed at evaluating the chemical control of the rust and the deposition of fungicide sprayed on soybean concerning different nozzles, and application volumes. A randomized complete-block design with four replications was used, in a factorial model (4 x 2) + 1: four spray nozzles (standard flat fan, pre-orifice flat fan, air induction flat fan and air induction twin flat fan), two spray volumes (115 and 160L ha-1) and the control (non-treated plot). Emgopa 313 soybean (long cycle) were sown. After the application of the fungicide tebuconazole, with the different nozzles and volume rates, the spray deposition in the plant canopy, the rust severity, and the yield were evaluated. The results showed that, despite the fact of the volume rate of 160L ha-1 and of the use of the standard flat fan nozzles have provided larger fungicide distribution uniformity in the plant canopy, there was not influence of the nozzle type neither of the application volume in the control of the rust as well as in the soybean yield. The fungicide has provided a good control of the rust, increasing the soybean yield, that was, on average, 41% superior to that obtained in the control.

Eucalyptus rust caused by Puccinia psidii and the threat it poses to Australia.

Abstract: Puccinia psidii, which causes the disease Eucalyptus rust, poses a threat to biodiversity in Australia and the Eucalyptus forest industry worldwide. It is native to South America and Central America and has spread to North America (Mexico, USA - Florida). In mid-2005, the rust was reported in Hawaii, USA, which means it is now present in the Pacific region.

Corrosion behavior of wire-arc-sprayed stainless steel coating on mild steel

Abstract: The corrosion characteristics of a wire-are-sprayed stainless steel coating on mild steel have been investigated in regards to atomizing gases and sealing treatment. Salt spray test was performed. The corrosion behavior of the coating was observed under a microscope succesively through a cycling test of wetting and drying in a salt solution. The sealing-treated coating was found to rust faster compared with the non-sealing-treated coating; it protected the mild steel substrate against corrosion, but even it deteriorated the coating itself due to the interruption of the substrate as an anode. The air-atomized coating ruste more heavily than the nitrogen-atomized one. Four different phases were observed in the coating in regards to corrosion behavior; namely, chromium-based oxide, iron-based oxide, chromium-depleted metallic phase, and stainless steel matrix phase. It was found that the chromium-depleted metallic phase and the iron-based oxide are non-corrosion-resistant, whereas the chromium-based oxide and the stainless steel matrix phase are corrosion-resistant.

Characterization of Rust on Fe-Cr, Fe-Ni, and Fe-Cu Binary Alloys by Fourier Transform Infrared and N2 Adsorption

Abstract: The structure and composition of the rust formed on the binary Fe-Ni, Fe-Cr, and Fe-Cu alloys exposed at different situations for 2 years and 3 years were investigated by N2 adsorption, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) to explore the role of alloying metals in the corrosion resistance of weathering steels. The rust particles formed in all exposure sites were strongly aggregated and microporous. The specific surface area (SA) obtained by N2 adsorption decreased and then increased by increasing the contents of Ni and Cr. The increase of SA, that is, the reduction of particle size of rust, was remarkable in the exposure site with a high airborne salinity. This result verifies that alloying metals are effective for the corrosion restraint of steels in Cl− environments such as coastal and marine districts. The content ratio of α-FeOOH to γ-FeOOH in rust (α/γ) showed a maximum at α/γ = ca. 0....

Responses to selection for partial resistance to crown rust in oat

Abstract: Crown rust, caused by the fungal pathogen, Puccinia coronata Corda var. avenae W.P. Fraser Ledingham, reduces kernel quality and grain yield in oat (Avena sativa L.). Partial resistance is considered to be a durable form of rust resistance. This study sought to evaluate the feasibility of simultaneously improving partial resistance to crown rust, grain yield, and seed weight in an oat population, and to estimate predicted and realized heritabilities for area under disease progress curve (AUDPC) and genetic correlations between AUDPC and agronomic traits in both crown rust-inoculated and fungicide-treated plots. A single cycle of selection for partial resistance to crown rust was performed. The initial (C0) and selected (C1) generations were evaluated in a field experiment in 2001 and 2002 at two Iowa locations. Selection on an index increased the levels of crown rust resistance, grain yield, and seed weight in crown rust2inoculated plots, and seed weight in fungicide-treated plots. However, the change for the grain yield in fungicide-treated plots was not significant. In both C0 and C1 populations, AUDPC was highly heritable (H 5 0.77 and 0.78 respectively), and was favorably correlated with grain yield, seed weight, and test weight measured in inoculated plots. Realized heritabilities for all traits except grain yield under fungicide treatment were consistent with predicted heritabilities. Our results suggested that index selection could increase levels of crown rust resistance, grain yield, and seed weight simultaneously.

Fungicide trials to determine the effect of brown rust on the yield of sugarcane variety n29

Abstract: Since the release of sugarcane variety N29 (genotype 84E1334) for commercial planting in the spring of 1997, severe infections of brown rust (Puccinia melanocephala) have been reported in this cultivar. Many growers have persevered with N29, risking substantial yield losses should the crop become infected. Two fungicide trials were established to assess the effect of brown rust on the yield of N29 in the KwaZulu-Natal Midlands where the disease is prevalent. The results of these trials are discussed.

Genetics of leaf rust resistance in the spring wheats ‘Ivan’ and ‘Knudson’ spring wheat

Abstract: Leaf rust caused by Puccinia triticina is a common and widespread disease of wheat in North America and worldwide. Durable genetic resistance to leaf rust in wheat has been difficult to achieve, since the virulence of the leaf rust pathogen to specific leaf rust resistance genes in wheat is highly variable. ‘Ivan’ and ‘Knudson’, hard red spring wheat cultivars recently released by AgriPro®, are highly resistant to leaf rust. The objective of this study was to determine the identity of leaf rust resistance genes present in both cultivars. ‘Ivan’ and ‘Knudson’ were crossed with ‘Thatcher’, a cultivar susceptible to leaf rust; the F1 plants were backcrossed to ‘Thatcher’; and the BCF1 plants (approximately 80 from each cross) were selfed to develop BCF2 families. The BCF2 families were tested as seedlings with different P. triticina isolates to determine the number and identity of leaf rust resistance genes that segregated in the BCF2 families. Both the BCF3 lines from selected resistant BCF2 plants and near...

A method for disease control in mon89788 soybean

Abstract: The present invention relates to a method to control diseases of MON89788 soybean by treatment with formulations and mixtures containing glyphosate. In particular, the formulations and mixtures are effective at controlling fungal diseases of MON89788. More specifically, the invention relates to a method to control the severity of leaf rust disease on MON89788.

Chromium-free rust inhibitive treatment method for metal products having zinc surface and metal products treated thereby

Abstract: Provided is a chromium-free surface treatment method which imparts practical rust inhibitive performance to a metal product having a zinc surface to which it was difficult to impart rust inhibitive performance of practical level. A conversion-coated film of zinc phosphate etc. is formed on the zinc surface of the metal product as pretreatment, and the silica-based film is formed by applying a chromium-free surface treatment agent which uses alcohol or mixture of water and alcohol as a solvent to the conversion-coated film. As a result, when an aqueous surface treatment agent containing alcohol is applied, it is possible to suppress the formation of white rusting for 72 hours or longer in the salt spray test.

Insect-transmitted urediniospores of the rust Puccinia punctiformis cause systemic infections in established Cirsium arvense plants

Abstract: Wandeler, H., and Bacher, S. 2006. Insect-transmitted urediniospores of the rust Puccinia punctiformis cause systemic infections in established Cirsium arvense plants. Phytopathology 96:813-818. The rust fungus Puccinia punctiformis has potential as a biological control agent for creeping thistle Cirsium arvense, because systemically infected shoots usually die before flowering. The mechanism of rust transfer as well as the spore type responsible for systemic infections have been a source of controversy. One possibility of successful transmission is the use of the weevil Ceratapion onopordi as a vector. Our results from a garden experiment show that urediniospores transmitted by the weevil are able to induce systemic infections in established thistle clones. Furthermore, the weevil origin and the date of rust treatment significantly influenced the number of rust-infected shoots. The earlier a shoot was treated, the higher the probability of rust transmission. These results challenge the current belief that teliospores passing through the soil and infecting root buds are the major cause of systemic infections in the field. Further research on biological control of creeping thistle should therefore concentrate on the application of urediniospores to enhance systemic rust infections.

Simulating the U.S. Impacts of Alternative Asian Soybean Rust Treatment Regimes

Abstract: Asian soybean rust (rust) is an emerging issue in U.S. crop production and was identified in nine states during 2004. Recent farm surveys indicate that many producers are adjusting their management practices to the possibility of a rust infestation. The economic and environmental impacts of such adjustments are not known in the medium run given these new developments. We combine 2005 data on the geographical distribution of the fungal pathogen that causes rust with 2005 information on the availability and material costs of fungicides to analyze three treatment strategies. Our results indicate a higher range of economic impacts than previous research has indicated, but are consistent with earlier findings indicating that rust infestations will likely result in reduced soybean production, reduced exports, and higher prices.

Multifunctional high-efficient metal anti-rusting liquid for removing oil

Abstract: A sort of descaling solution is used on metallic material and metalwork surface to wipe off rustiness. It contains the following material: phosphoric acidu¼sodium silicateu¼sodium dodecyl benzene sulfonateu¼hexamethylene tetramineu¼triethanolamine, citric acid , OP-10 emolsifier,industrial salt and water. It was used to wipe off various rust, oxide skin and greasy dirt from metal. Advantages are stabilityu¼high efficiency ,non-pollutionu¼safety and easiness to handle.