Showing papers on "Rust published in 1991"

Soybean rust development and the quantitative relationship between rust severity and soybean yield

Abstract: Phakospora pachyrhizi was inoculated on two soybean (Glycine max) genotypes at three different reproductive growth stages (GS) in four trials. Leaf rust was more severe on Taita Kaohsiung No. 5 (TK 5), a commercial cultivar, than on SRE-B15-A (B15 A), a genotype selected for tolerance to leaf rust. At GS R6, the percentage of leaf area infected ranged from 14 to 95% for TK 5 and from 0 to 34% for B15 A. Values for area under disease progress curve (AUDPC) were significantly greater for TK 5 than B15 A. Yields in fungicide-protected plots ranged from 2,312 to 3,546 kg/ha and were not significantly different between the genotypes (...)

Genetics of Adult‐Plant Leaf Rust Resistance in ‘Chinese Spring’ and ‘Sturdy’ Wheats

Abstract: The common wheat (Triticum aestivum L.) cultivars Chinese Spring and Sturdy have adult-plant resistance to leaf rust caused by Puccinia recondita Rob. ex Desm. To study the genetics of this resistance both cultivars were crossed and backcrossed to ‘Thatcher’, a leaf rust susceptible cultivar. The two cultivars or resistant selections from the above crosses were also crossed with backcross lines having Lrl2, Lr13, and Lr34 genes for adult-plant leaf rust resistance. The backcross F₂ families and F₂ populations were grown in a field rust nursery artificially inoculated with a mixture of P. recondita isolates. The segregation for rust reaction of adult plants indicated that both cultivars have a combination of genes Lrl2 and Lr34. To assist in the identification of Lr34 in these cultivars, adult-plant leaf rust resistance from each cultivar was transferred into Thatcher. Contribution from Res. Stn., Winnipeg. Paper no. 1408.

Prehaustorial and post-haustorial resistance to wheat leaf rust in diploid wheat seedlings.

Abstract: The histological reaction of 13 diploid wheat accessions (Triticum monococcum s.l.) to two isolates of wheat leaf rust (Puccinia recondita f. sp. tritici) was investigated and compared with the nonhost reactions to rye and barley leaf rust. The resistance of diploid wheat to wheat leaf rust ranged from almost completely prehaustorial without necrosis to almost completely posthaustorial with frequent necrosis. This variation depended on the diploid wheat accession rather than on the wheat leaf rust isolate (...)

Reduction in yield of winter wheat in North Carolina due to powdery mildew and leaf rust

Abstract: The relationships between yield reductions and severity of powdery mildew and leaf rust were examined on winter wheat cultivars Saluda and Coker 983. Plots were established in central and eastern North Carolina in the fall of 1987 and 1988. Triadimefon and/or benomyl were applied to wheat foliage for control of powdery mildew and leaf rust. Significant differences in disease development resulted from fungicide treatments, from differences in resistance of the cultivars, and from different environments. Differences in 500-kernel weight and grain yield were observed even when upper leaves had little disease in some environments (...)

The effect of rust on yield of faba bean cultivars and slow-rusting populations

Abstract: Field studies were conducted in 1983 and 1984 to assess the effect of rust (Uromyces viciae-fabae) on the yield components, pods per plant, seed per plant, seed per pod, total dry matter and harves...

Paint stripper compositions containing gamma-butyrolactone

Abstract: Aggressive, water-soluble coating remover compositions are disclosed. The compositions contain γ-butyrolactone, an organic acid, and water, and optionally include solvents, surfactants, thickeners, and rust inhibitors. The coating removers of the invention are uniquely effective in that they are both water rinsable and capable of removing highly crosslinked coatings.

Application of Infrared Spectroscopy for Investigation of Rust Phase Component Conversion by Agents Containing Oak Tannin and Phosphoric Acid

Abstract: Conversion of synthetic phase components of rust in aqueous solutions of oak tannin, of phosphoric acid, and of both these substances is described. The main components of atmospheric rust (viz., lepidocrocite, goethite, and magnetite) have been converted. Time of conversion ranged from 1 day to 12 months. The investigations were carried out using infrared spectroscopy.

Resistance of wild emmer wheat to stem rust : ecological, pathological and allozyme associations

Abstract: Seedling resistance to wheat stem rust was determined in populations of wild emmer wheat, Triticum dicoccoides, and characterized by means of ecological factors and allozyme genotypes. Reactions to wheat stem rust were studied in 102 single plant accessions of T. dicoccoides from ten populations by inoculation with Puccinia graminis tritici race 14, isolate GSR-739. Six populations displayed different degrees of response polymorphism with reactions ranging from high resistance to complete susceptibility, whereas four populations contained only susceptible plants. In some of the accession, unexplained intrasib variation in resistance and intraplant variation of infection-types were found. Resistance to stem rust was negatively correlated with two ecological factors, altitude and number of ‘Sharav’ (hot-dry) days which are unfavorable to disease development. Variation in stem rust response was shown to exist in ecogeographic regions where climatic variables enhanced the development of the fungus, conceivably maintained by natural selection. Likewise, allozyme genotypes, single or in multiple loci combinations, appeared to be associated with resistance or susceptibility to rust. Such association need to be verified by genetic studies in order to become established as useful markers.

Characterization of stem rust resistant derivatives of wheat cultivar Amigo

Abstract: Originally developed for resistance to greenbug derived from Insave rye, Amigo wheat carries two genes for resistance to stem rust. One of these genes is associated with a rye chromosome 1RS segment carrying the Sec-1 protein marker and presumably greenbug resistance. The second gene which is genetically linked to leaf rust resistance is associated with an Agropyron-derived segment. Rust tests in Canada confirmed that these genes were Sr24 and Lr24. In contrast to Agent and certain 3D/Ag derivatives from Dr. E.R. Sears, the Amigo source of Sr24/Lr24 freely recombined with white seed colour during backcrossing.

Effects of Aphis fabae and Uromyces viciae-favae on the growth of a susceptible and an aphid resistant cultivar of Vicia faba.

Abstract: Summary Damaging effects of either black bean aphid (Aphis fabae), broad bean rust (Uromyces viciae-fabae), or the combination of both were investigated on a susceptible (cv. Diana) and an aphid resistant (cv. Bolero) cultivar of Vicia faba. When compared with rust, aphids caused greater reductions of root dry weight, shoot dry weight, leaf area, and mean relative growth rate. The mean unit leaf rate was also reduced whereas the leaf area ratio was not affected. The damage caused per aphid was highest on the susceptible cultivar. Rust induced damage did not differ between the cultivars. Concomitant infestation with both pests only resulted in additive damage. The population development of aphids was delayed on partially resistant plants. High temperature and rust infection reduced the total number of aphids the plants were able to support but not the level of resistance. Thus the specific damaging effect per aphid was increased.

Effect of Film-Forming Compounds on the Development of Leaf Rust on Wheat Seedlings

Abstract: The effect of film-forming antitranspirants and glues on the development of leaf rust (caused by Puccinia recondita f. sp. tritici) was assessed on wheat seedlings (Triticum aestivum «Ceeon»). When applied before rust inoculation, the compounds Bio-Film, Folicote, and Vapor Gard markedly reduced the number of pustules per square centimeter. Postinoculation application had a significantly smaller effect on suppression of rust development (.)

The reaction of x Tritordeum and its Triticum spp. and Hordeum chilense parents to rust diseases

Abstract: Hexaploid and octoploid tritordeums and their parents Hordeum chilense and Triticum spp. were screened for resistance to isolates of wheat and barley yellow and brown rusts. All H. chilense lines were highly resistant to both wheat and barley brown rust, few lines were susceptible to wheat yellow rust while susceptibility to barley yellow rust was common. In general the resistance of tritordeum is predominantly contributed by the wheat parent and apparently the genes for resistance in H. chilense are inhibited in their expression by the presence of the wheat genome.

Registration of KS00WGRC44 Leaf Rust‐Resistant Hard Red Winter Wheat Germplasm

Abstract: KS90WGRC10 (Reg. no. GP-334, PI 549278), is a leaf rust (caused by Puccinia recondita Roberge ex Desmaz.) resistant hard red winter wheat (Triticum aestivum L.) germplasm line developed cooperatively by USDA-ARS, the Kansas Agricultural Experiment Station, and the Wheat Genetics Resource Center, Kansas State University. It was released as a germplasm in September 1990. KS90WGRC10 seedlings produced low leaf infection type (QIC) with 30 different cultures of P. recondita. Adult plants exhibited an immune reaction to leaf rust infection at four Kansas field locations in 1990. The pedigree of KS90WGRC10 is 'TAM 107'*3/TA 2460. TA 2460 is a leaf rust-resistant accession ofAegilops squarrosa L., collected by Kyoto University, Japan, near Khoshyailagh in north-central Iran. A direct TAM 107/TA 2460 hybrid was backcrossed as a female to TAM 107 in spring 1987, and TAM 107 was pollinated by a resulting BC^ plant in the following fall. KS90WGRC10 is a BC2F2-derived F5 line produced by self-pollinating a single BC2F3 family that was homogeneous for immune reaction to PRTUS25. Leaf rust resistance in KS90WGRC10 is governed by a dominant gene on chromosome ID (unpublished data). This gene segregates independently of the Lr21 locus and the gene carried by KS89WGRC7 (1), also located on ID (unpublished data), and the spectra of reaction of the three genes to a range of leaf rust cultures differ. KS90WGRC10 is segregating for resistance to wheat soilborne mosaic and wheat spindle streak mosaic viruses. The source of the resistance is TA 2460, although its genetic control has not yet been determined. Otherwise, KS90WGRC10 is similar to TAM 107 in height, maturity, level of resistance to the wheat curl mite (Eriophyes tulipae Keifer), and general phenotype. It is segregating for alleles from TAM 107 and TA 2460 at the Gli-Dl locus on chromosome ID. Small quantities of seed of KS90WGRC10 are available upon written request. Appropriate recognition of source should be given when this germplasm contributes to research or development of new cultivars. Seed stocks are maintained by the Wheat Genetics Resource Center, Dep. of Agronomy, Throckmorton Hall, Kansas State University, Manhattan, KS 66506-5501.

Plant population heterogeneity and pathogen and herbivore levels: a field experiment.

Abstract: The identity of neighbouring plants in a population is thought to affect the disease levels of an individual plant: disease levels are expected to be higher for susceptible plants surrounded by other susceptible plants as compared to susceptible plants that have resistant plants as neighbours. To explore this idea, plants in a natural population of the annual sunflower, Helianthus annuus, were scored in 1988 for levels of the rust pathogen Puccinia helianthi. Progeny of plants with high rust levels (families predicted to be susceptible to the disease) were grown in 1989 in a series of field plots at either high frequency (all plants in a plot of one family) or in low frequency (a plot with plants of many families). There was a positive correlation between rust levels of the parent plants in 1988 and their progeny in 1989, but the frequency of a family in the experimental plots did not affect rust levels. Generally low rust levels at the site, as well as other factors, probably contributed to the absence of a frequency effect. Herbivore levels and plant survival and reproduction varied among plots, but were not affected by the plot composition.

Biology and effectiveness of Uromyces heliotropii Sred., a potential biological control agent of Heliotropium europaeum L.

Abstract: summary The rust fungus Uromyces hellotropii Sred. shows potential for the biological control in Australia of the common heliotrope (Heliotropium europaeum L.), an annual weed of European origin. Teliospores of the pathogen remained viable when stored for one year at temperatures between −8 and 20°C, and carried infection over from one summer growing season to the next under a Mediterranean-like climate. Both in glasshouse and field inoculation experiments, the rust rapidly killed infected plants and reduced or prevented seed production. U. heliotropii appears capable of surviving in the Mediterranean-like climatic areas of Australia where common heliotrope is a problem weed and is sufficiently virulent to cause significant field infection.

The spatial structure of spontaneous epidemics of different diseases in a groundnut plot

Abstract: Spontaneous epidemics of rust, early leaf spot, late leaf spot, andRhizoctonia blight simultaneously developed in a groudnut plot. Geostatistical techniques were used to describe and compare the spatial patterns of epidemics.Rhizoctonia blight exhibited a strong aggregative structure, contrasting with leaf spots and rust. The latter disease developed a general epidemic, in combination with local intensification. A strong negative interaction between rust and early leaf spot, and a close correspondence between rust intensification andRhizoctonia blight development were indicated.

Inoculum pressure and the development of stem rust epidemics in barley

Abstract: The effects of inoculum pressure on the development of epidemics of Puccinia graminis tritici in two barley cultivars with different levels of resistance were examined in two field experiments. Treatments were established by inoculation of foci within plots and/or the strategic use of fungicides. Additional 'rust-free' treatments were maintained to provide comparisons of grain yield and quality. Relationships between rust severity, rust incidence and grain yield and quality were also examined. Initial inoculum levels were important in determining disease severity and incidence for individual epidemics; however, severe epidemics developed under most 'rusted' treatments of the susceptible cultivar Galleon and reduced grain yield by up to 58%. Epidemics under corresponding treatments of the moderately resistant cultivar Grimmett were less severe, and the value of the resistance was evident with yield losses not exceeding 12%. Yield reductions were usually associated with reduced grain size and weight.

Comparison of the effect of leaf rust on the grain yield of resistant, partially resistant, and susceptible spring wheat cultivars

Abstract: Three hypersensitive resistant, six partially resistant (slow rusting), and one susceptible spring bread wheat (Triticum aestivum L.) cultivars were evaluated for grain yield, test weight, and kernel weight under artificially created epiphytotics of leaf rust disease (caused by Puccinia recondita f. sp. tritici) with and without fungicide protection for three years. Rusted plot yields were 4 percent lower compared to fungicide-protected plot yields for cultivars with hypersensitive resistance. In rusted plots, grain yield and kernel weight averaged 8 percent less for cultivars with partial resistance but varied from 2 to 20 percent less depending on cultivar. The susceptible check cultivar, Yecora 70, averaged 27 percent lower grain yield, 22 percent lower kernel weight, and 6 percent lower test weight in rusted plots. Slight reduction in test weight was also observed for each cultivar. Losses in grain yield could, therefore, be reduced to levels similar to those of hypersensitive resistant cultivars by the use of partial resistance. We discuss the sustainability of partial genetic resistance to leaf rust. Since partial resistance is expected to be durable, and since rust levels and effects on yield in farmers' fields are likely to be less than in this experimental plot study, partial resistance should give long-lasting resistance at a negligible cost in yield that is insufficient to justify the use of fungicides.

Use of multispectral radiometry in wheat yellow rust experiments

Abstract: Winter-wheat field fungicide experiments were monitored by multispectral radiometry to determine yellow rust impact on crop growth and to predict yield loss caused by disease. Spectral reflectance data were highly correlated with yellow rust severity. Linear regression models with spectral ratios as independent variables explained 90-93% of the variation in yield between plots with different treatments of fungicide. The area under the NIR/Red curve, calculated from heading to soft-dough growth stages, was a good predictor of yield loss determined at harvest.

Evaluation of Components of Partial Resistance to Rust in Flax

Abstract: (1991). Evaluation of Components of Partial Resistance to Rust in Flax. Canadian Journal of Plant Pathology: Vol. 13, No. 3, pp. 212-217.

Reduction in the Rate and Duration of Grain Growth in Wheat Due to Stem Rust and Leaf Rust

Abstract: Leaf and/or stem rust epidemics differing in date of disease onset after anthesis and area under the disease progress curve (AUDPC) were established at various distances from rows of inoculated winter wheat in two fields during each of the 1986 and 1987 growing seasons. Rate and duration of grain growth were reduced by rust. Piecewise linear regression proved to be useful for describing the nonlinear growth curves. Square root-transformed grain dry weight increased linearly at a similar rate (0. 19-0.21 mg 1/2 /day) at each of four field sites for at least the first 12 days from anthesis (DFA) (...)

An advisory model for control of Puccinia recondita in winter wheat

Abstract: Epidemics ofPuccinia recondita and resulting yield loss of winter wheat were studied in field experiments over three seasons in the Netherlands. Results are reported and used to construct an advisory model for control of brown rust, based on rust monitoring. If the fraction of leaves with rust (I) at a certain development stage is determined, the average number of rust sori per leaf (M) was estimated by: M=EXP(1.84+1.39ln(ln[1/(1-I)]). The final number of sori per leaf (Mf) at early dough was forecast by an exponential growth: Mf=M·EXP(RGR·t). The relative growth rate (RGR) averaged 0.163/day and the forecasting period, t, until early dough, was derived from published data. The forecast number of sori-days per leaf (S, AUDPC-value) was then obtained by: S=(Mf-M)/RGR. Yield loss (kg/ha) by brown rust was 1.15 times the number of sori-days per leaf at low rust intensities. The efficacy of the fungicides used was 85%. The forecast avoidable yield loss (L, kg/ha) was calculated by: L=0.85 (1.15 S). Economic thresholds for brown rust control at different development stages are given for Dutch wheat fields at a cost level of 270 kg/ha for one fungicide application.