Showing papers on "Rust published in 1995"

Successes in breeding for and managing durable resistance to wheat rusts.

Abstract: Stripe rust, leaf rust, and stem rustcaused by Puccinia striiforrnis Westend., Puccinia recondita Roberge ex Desmaz., and Puccinia graminis Pers., respectively-have been considered to be the most widely destructive diseases of wheat (Triticum aestivum L.) in the world. Rust epidemics have been common throughout history and have frequently caused severe yield losses. During the first half of the twentieth century, rust resistance was short-lived. Within a few years after the release of a new resistant cultivar, new, virulent races (pathotypes) of the rust pathogens would appear and severely damage the previously resistant cultivar. Within the last 30 to 40 years, major progress has been made in developing cultivars with superior, more sustainable resistance to the rusts, and in the application of improved methods of managing that resistance. Consequently, rust epidemics have been infrequent, and when they have occurred, damage caused by the rusts has been less severe and less extensive. The following is a brief discussion of some of the successes and a few of the failures in controlling the rusts. The information is based on firsthand knowledge of the rusts and corroborative information from many other rust specialists. Emphasis will be on control of the diseases in North America. Wheat production and rust development in North America. The environmental conditions that affect wheat production and rust epidemics have a major impact on the strategies and methods of breeding for rust resistance and the management of that resistance. Wheat is grown in many regions of North America under a wide range of environmental conditions. It is the environment within those regions that determines the wheat types and market classes that are grown, the importance of each of the three rusts, and the effec-

Screening methods and sources of resistance to rust and late leaf spot of groundnut. Information Bulletin no. 47

Abstract: Rust and late leaf spot are the most serious fungal diseases of groundnut worldwide, and can cause severe yield losses, particularly when they occur together. This Bulletin describes simple and effective field screening methods to identify genotypes with resistance to these diseases. Production of inoculum, sowing and inoculation of test genotypes, and disease assessment in the field, using a 1-9 scale, are discussed. These methods were used dUring 1977-89 to evaluate ICRISAT's world collection of over 12 000 groundnut accessions. Several reliable sources of resistance to rust and/or late leaf spot were identified, and are listed here-124 lines resistant to rust, 54 lines resistant to late leaf spot, and 29 lines with combined resistance. An extensive bibliography is also presented, for those who require more detailed information on specific aspects of the diseases.

Screening Methods and Sources of Resistance to Rust and Late Leaf Spot of Groundnut

Abstract: Rust and late leaf spot are the most serious fungal diseases of groundnut worldwide, and can cause severe yield losses, particularly when they occur together. This Bulletin describes simple and effective field screening methods to identify genotypes with resistance to these diseases. Production of inoculum, sowing and inoculation of test genotypes, and disease assessment in the field, using a 1-9 scale, are discussed. These methods were used dUring 1977-89 to evaluate ICRISAT's world collection of over 12 000 groundnut accessions. Several reliable sources of resistance to rust and/or late leaf spot were identified, and are listed here-124 lines resistant to rust, 54 lines resistant to late leaf spot, and 29 lines with combined resistance. An extensive bibliography is also presented, for those who require more detailed information on specific aspects of the diseases.

Disease severity and yield of pure‐line wheat cultivars and mixtures in the presence of eyespot, yellow rust, and their combination

Abstract: Five winter wheat cultivars, six two-component cultivar mixtures, and one four-way mixture were grown in the presence of yellow rust, eyespot, both diseases, and neither disease for three seasons. On average, mixtures reduced the severity of yellow rust relative to their component pure stands by 53%. The four-component mixture provided better yellow rust control than did the two-way mixtures. Eyespot severity was reduced through mixing only in the absence of yellow rust and by only three of the seven mixtures (mean reduction = 13%). Yellow rust was 13% less severe in the presence of eyespot, and eyespot was 10% more severe in the presence of yellow rust. Averaged over all years, the mixtures increased yield relative to the pure stands by 6·2, 1·7, 7·1, and 1·3% in the presence of yellow rust, eyespot, both diseases, and neither disease, respectively. Two mixtures provided significant yield increases over the means of their component pure stands (7% and 9%) in the presence of eyespot even though one of them did not significantly reduce eyespot severity. Accounting for all disease treatments and years, four mixtures provided distinctly higher yield increases than the other three. In mixtures containing a resistant cultivar and a cultivar susceptible to eyespot, yield loss by the susceptible cultivar was not compensated for by increased yield of the resistant cultivar. The mixtures showed improved yield stability relative to the pure stands, with the four-component mixture being particularly stable.

The L6 gene for flax rust resistance is related to the Arabidopsis bacterial resistance gene RPS2 and the tobacco viral resistance gene

Abstract: The L6 rust resistance gene from flax was cloned after tagging with the maize transposable element Activator. The gene is predicted to encode two products of 1294 and 705 amino acids that result from alternatively spliced transcripts. The longer product is similar to the products of two other plant disease resistance genes, the tobacco mosaic virus resistance gene N of tobacco and the bacterial resistance gene RPS2 of Arabidopsis. The similarity involves the presence of a nucleotide (ATP/GTP) binding site and several other amino acid motifs of unknown function in the N-terminal half of the polypeptides and a leucine-rich region in the C-terminal half. The truncated product of L6, which lacks most of the leucine-rich C-terminal region, is similar to the truncated product that is predicted from an alternative transcript of the N gene. The L6, N, and RPS2 genes, which control resistance to three widely different pathogen types, are the foundation of a class of plant disease resistance genes that can be referred to as nucleotide binding site/leucine-rich repeat resistance genes.

Rust-removing alkali metal hydrogen citrate composition

Abstract: A rust-removing composition comprises alkali metal hydrogen citrates, water, optionally citric acid, and optionally a thickener. The invention further provides a method for removing rust from rusted metal surfaces, concrete surfaces, and the siliceous surfaces of natural stone by applying the composition, allowing contact until substantially all of the rust is removed, and washing away the composition and dissolved rust with water.

Effect of Leaf Rust on Yield Components of Winter Rye Hybrids and Assessment of Quantitative Resistance

Abstract: Leaf rust (Puccinia recondita f. sp. secalis) is common in all winter rye growing areas, but little is known about its effect on yield in hybrid rye. Ten single crosses without any hypersensitive response to leaf rust were grown at three environments (Hohenheim, 1991 ; Halle, 1991 ; Hohenheim, 1992) in an inoculated and a non-inoculated, fungicide protected, treatment block. Resistance traits were mean leaf rust ratings of the upper three leaves (F-2, F-1, F) assessed with 10 arbitrarily chosen tillers per plot at four assessment dates, selected leaf rust rating on two leaves at one assessment date, and area under disease progress curve (AUDPC). Additionally, kernel number per head, grain weight per head and thousand kernel weight were assessed on the individual tillers in three environments and plot yield and thousand kernel weight of the thresheld plot samples in two environments. Correlations among AUDPC values and mean leaf rust ratings on the respective leaves and selected leaf rust rating were high (r 0.9, P = 0.01). Resistance among the upper three leaves was closely correlated (r 0.9, P = 0.01) for AUDPC value and mean leaf rust rating. Leaf rust epidemics significantly reduced grain weight per head, plot yield and thousand kernel weight in three environments ; kernel number per head was not significantly affected. Thousand kernel weight was reduced on average by 14% ranging from 11 to 27% among single crosses. Significant genotypic variation was observed for the affected yield components at Hohenheim 1991 and 1992. Genotype-year interaction variance was large in the combined analysis for yield components. Quantitative resistance can be assessed by visual rating of maximal two leaves at one optimal assessment date. Relative thousand kernel weight from thresheld plot samples can be used additionally as resistance trait when disease severity is high enough during kernel filling.

Soil phosphate status modifies response of mycorrhizal and non‐mycorrhizal Senecio vulgaris L. to infection by the rust, Puccinia lagenophorae Cooke

Abstract: summary The impact of rust infection (Puccinia lagenophorae Cooke) on growth of mycorrhizal and non-mycorrhizal Senecio vulgaris L. was examined under three levels of phosphorus fertilization. Seeds were then collected from infected and control plants and germination, seed chemistry and offspring vigour were examined. Rust infection did not become established on plants which were phosphorus limited, but on hosts fed with medium or high levels of P, the proportion of total leaf number exhibiting infection was a function of leaf production. Capitula production was decreased by rust infection and increased by mycorrhizal colonization in plants fed with a medium concentration of P. In plants fed with a high P concentration, leaf number was reduced by rust infection of mycorrhizal plants, whilst rust was deleterious to both mycorrhizal and non-mycorrhizal plants grown with a medium P supply. However, the effects of the rust were less marked in the mycorrhizal plants. Seed production and weight were unaffected by fungal treatments, although percentage germination of the resultant seeds was reduced by maternal mycorrhizal colonization and enhanced in seed from rusted, mycorrhizal plants grown at high soil P. The amount of total C, N and P was also reduced by maternal mycorrhizal infection at high soil P and increased in seeds from rusted, mycorrhizal mothers. Vigour of offspring produced from treated mother plants was influenced by mycorrhizal × phosphorus and rust × phosphorus interactions with respect to bud and leaf numbers. Mycorrhizal infection of mother plants grown with a medium P supply benefited the offspring as increased leaf and bud production was observed, but rusted mothers at the same P level produced offspring with reduced leaf number and potential fecundity.

Evaluating different plant extracts against three major diseases of mulberry

Abstract: The effects of 10% alcoholic water extracts of fresh plant parts from 20 different species were investigated on the development of powdery mildew (Phyllactinia corylea) leaf spot (Pseudocercospora mori) and leaf rust (Cerotelium fici) of mulberry during 1992-93 and 1993-94 in West Bengal, India The pooled data of these 2 years revealed that the extract of Adhatoda zeylanica was most effective in decreasing the severity of all the diseases followed by extracts of Azadirachta indica, Launaea coromandelica [Lannea coromandelica] and Oxalis corniculata which significantly minimized powdery mildew and leaf rust, while those of Celosia argentia and Chromolaena odorata reduced leaf spot and leaf rust Extracts from several other plant species exhibitedan ability to reduce either leaf rust or powdery mildew disease

Stem and Crown Rust Resistance in the Wisconsin Oat Selection X1588‐2

Abstract: The Wisconsin oat (Avena sativa L.) selection X1588-2 has reacted either with mesothetic (moderately resistant) or 0;1 (highly resistant) infection types to races of Puccinia graminis Pers. f. sp. avenae Eriks. & E. Henn. (stem rust). This selection also is resistant to some pathotypes of P. coronata Corda f. sp. avenae Eriks. (crown rust). The objectives of this study were to identify the genes in X1588-2 responsible for the rust resistance and to determine the usefulness of this line as a source of resistance in oat breeding. Tests with 45 races of P.g. avenae showed that X1588-2 was highly resistant to races that were avirulent to genes Pg3 and/or Pg4 and was moderately resistant to all other races. These results and the pedigree of X1588-2 indicated the presence of stem rust resistance genes Pg3, Pg4, and Pg10 in X1588-2. The presence of these genes was further indicated in tests of seedlings of segregating BC₁F₁ and BC₁F₂ populations from a cross of X1588-2 with the susceptible cultivar Makuru. Resistance to crown rust in X-1588-2 was conferred by a gene designated as Pc95. The resistance conferred by Pc95, however, was not effective against a sufficient range of pathotypes of P. coronata to be a useful source of resistance. Genes Pg3 and Pg4 are ineffective against current North American populations of P.g. avenae. Gene Pgl0, however, appears to confer a moderate but very broad range of resistance and may be a useful source of resistance in oat breeding. Contribution no. 1586, Agriculture and Agri-Food Canada Research Centre, Winnipeg.

Rust resistance in Triticum cylindricum Ces. (4x, CCDD) and its transfer into durum and hexaploid wheats.

Abstract: In order to counteract the effects of the mutant genes in races of leaf rust (Pucciniu recondita f.sp. tritici Rob. ex Desm.) and stem rust (P. graminis f.sp. tritici Eriks. & Henn.) in wheat, exploration of new resistance genes in wheat relatives is necessary. Three accessions of Triticum cylindricum Ces. (4x, CCDD), Acyl, Acy9, and Acyll, were tested with 10 races each of leaf rust and stem rust. They were resistant to all races tested. Viable F, plants were produced from the crosses of the T. cylindricum accessions as males with susceptible MP and Chinese Spring phlb hexaploid wheats (T. aestivum, 6x, AABBDD), but not with susceptible Kubanka durum wheat (T. turgidum var. durum, 4x, AABB), even with embryo rescue. In these crosses the D genome of hexaploid wheat may play a critical role in eliminating the barriers for species isolation during hybrid seed development. The T. cylindricum rust resistance was expressed in the F, hybrids with hexaploid wheat. However, only the cross MPlAcyl was successfully backcrossed to another susceptible hexaploid wheat, LMPG-6. In the BC2F2 of the cross MPlAcylIlLMPG-6/3lMP, monosomic or disomic addition lines with resistance to either leaf rust race 15 (infection types (IT) 1=, 1, or 1'; addition line 1) or stem rust race 15B-1 (IT 1 or 1'; addition line 2) were selected. Rust tests and examination of chromosome pairing of the F, hybrids and the progeny of the disomic addition lines confirmed that the genes for rust resistance were located on the added T. cylindricum C-genome chromosomes rather than on the D-genome chromosomes. The T. cylindricum chromosome in addition line 2 was determined to be chromosome 4C through the detection of RFLPs among the genomes using a set of homoeologous group-specific wheat cDNA probes. Addition line 1 was resistant to the 10 races of leaf rust and addition line 2 was resistant to the 10 races of stem rust, as was the T. cylindricum parent. The added C-genome chromosomes occasionally paired with hexaploid wheat chromosomes. Translocation lines with rust resistance (2n = 21 11) may be obtained in the self-pollinated progeny of the addition lines through spontaneous recombination of the C-genome chromosomes and wheat chromosomes. Such translocation lines with resistance against a wide spectrum of rust races should be potentially valuable in breeding wheat for rust resistance.

Field evaluation of leaf rust severity, yield loss and quality characteristics in near-isogenic wheat lines with Lr29, Lr35 or Lr37

Abstract: The potential of three Lr genes in the wheat lines RL6080 (Thatcher*6/Lr29), RL6081 (Thatcher*8/Lr37) and RL6082 (Thatcher*6/Lr35) was evaluated in field experiments. Leaf rust reaction types on flag leaves of lines with Lr29, Lr35 or Lr37 varied between resistance and moderate susceptibility. Severity ratings on these lines did not exceed 5%. Leaf rust infection reduced grain mass in Thatcher by 10.4% whereas lines with Lr29, Lr35 or Lr37did not sustain significant losses (+1.0, 2.6 and 1.0%, respectively). According to grain and flour protein concentration, flour yield, loaf volume and the baking strength index, no deleterious quality characteristics appeared to be genetically associated with Lr29, Lr35 or Lr37. The dough development time of RL6080 was shorter, and that of RL6081 longer than the control.

Lack of durability of resistance to cereal rusts in wheat when selection is for complete resistance.

Abstract: Twenty-one bread-wheat entries were selected after careful screening for complete or near-complete resistance to yellow rust (Puccinia striiformis), stem rust (P. graminis), and leaf rust (P. recondita). In 1987, the 21 entries were intercrossed in a near-half diallel scheme. The resulting 190 F 2 populations were advanced to F 7 under selection for complete resistance to the three rusts and for good agronomic types. In 1992 the 21 parents and 140 selected F 7 lines were assessed for their resistance to the three rusts. Of the 21 parents, 12 showed a breakdown of yellow rust resistance, five a breakdown of stem rust resistance and two a breakdown of leaf rust resistance. In addition, several of the 140 selected F 7 lines, all still resistant in F 6 , had become susceptible to one or more of the rusts. It appears that a progression towards more complex races, especially of yellow rust, is inevitable for the wheat-cereal rust patho-systems when the selection is for complete or near-complete resistance.

Chrysanthemum white rust in New South Wales

Abstract: The outbreak of Chrysanthemum white rust in New South Wales and the subsequent eradication campaign is outlined. The failure of the eradication campaign was due to many factors including poor chemical control, possible aerial spread and poor grower co-operation. The economic impact of the disease is briefly outlined.

Effect of rust (Uromyces viciae‐fabae) on yield components of faba bean

Abstract: Epidemics of faba bean rust (Uromyces viciae-fabae) differing in duration and final severity were induced by a point inoculation. Relationships between disease severity observed on three canopy layers (top, middle and bottom) at different assessment dates and yield components (grain weight per stem, average grain weight, number of grains per pod and number of pods per stem) were established. Epidemics occurring after the initiation of pod setting had no effect on yield components. Earlier epidemics significantly decreased the grain weight per stem, the average grain weight, and the number of pods per stem, but only marginally affected the number of grains per pod. The yield components generally decreased with increasing severity level, but a few parabolic relationships were observed at a late stage in crop development. The effect of rust on yield components could be predicted by a critical point model using disease severity assessed on the middle or bottom canopy layer in the mid-flowering stage. Rust severity greater than 5% during that critical stage would substantially decrease final yield, and fungicide spraying against rust would be advised.

Resistance and associated yield losses from rust (Uromyces trifolii-repentis Liro) in midseason cultivars of Trifolium subterraneum L. var. subterraneum L. and var. yanninicum Katzn. et Morley

Abstract: A field study was conducted to quantify the effect of rust on the herbage production and seed yield of 4 new midseason cultivars of Trifolium subterraneum (Denmark, Gosse, Goulburn, Leura) and to compare their performance with 8 current commercial cultivars. Leura, Gosse, and Goulburn were all resistant to rust, with Leura most resistant. Denmark was not resistant to rust, but was much less susceptible than Green Range and marginally less susceptible than Mt Barker. By the end of the season, rust had reduced herbage yield in Green Range, Junee, Karridale, and Seaton Park (32, 23, 22, 18%, respectively) but did not affect any new cultivar. Rust reduced the seed yields of all cultivars except Goulburn, Larisa, and Leura. Seed yields of Green Range, Woogenellup, Mt Barker, Seaton Park, Denmark, Esperance, Karridale, Gosse, and Junee were reduced by 75, 70, 58, 55, 49, 47, 40, 40, and 38%, respectively. Rust also reduced the size of seed in all cultivars except Goulburn.

Rust proof pigment composition and rust proof coating containing the same

Abstract: PURPOSE: To provide a rust proof pigment composition used for general purposes, containing no zinc, being non-polluting and excellent in rust proofing and a rust proof coating CONSTITUTION: This rust proof pigment composition comprises 95-20wt% of at least one phosphate selected from among aluminum phosphate, titanium phosphate, zirconium phosphate and cerium phosphate and 5-80wt% calcium methasilicate This rust proof coating is constituted by allowing to contain the same composition As the phosphate, aluminum dihydrogen tripolyphosphate, aluminum methaphosphate, titanium pyrophosphate, titanium hydrogen orthophosphate, zirconium hydrogen methaphosphate and cerium hydrogen orthophosphate are preferable

The inheritance of stem rust and leaf rust resistance in some Ethiopian wheat collections

Abstract: Common and durum wheat populations obtained from Sweden and originally collected in Ethiopia were screened for resistance to steum rust and leaf rust. Resistant selections of common wheat were crossed and backcrossed with either stem rust susceptible RL6071, or leaf rust susceptible Thatcher. Genetic studies, based largely on tests of backcross F2 families, showed that four of the selections had in common a recessive gene SrA. Plants with this gene were resistant (1+ infection type) to all stem rust races tested. This gene was neither Sr26 nor Sr29. The resistance of other selections, based on tests with an array of rust isolates, was due to various combinations of Sr6, 8a, 9a, 9d, 9c, 11, 13, 30, and 36. One of the selections had linked genes, Lr19/Sr25. Another selection had a dominant gene for resistance (;1 infection type) to all the races of leaf rust. With the possible exception of this gene for leaf rust resistance and SrA, no obviously new resistance was found.

Rust preventive steel plate for fuel tank, excellent in workability, corrosion resistance, and weldability

Abstract: PURPOSE: To provide a rust preventive steel plate for fuel tank, combining excellent corrosion resistance, workability, and weldability, by applying, as an after treatment film, an organic - inorganic combined coating having respectively specified composition and coating weight, at the time of hot dip tin - zinc alloy coating. CONSTITUTION: This steel plate is (1) a rust preventive steel plate for fuel tank, combining excellent workability, corrosion resistance, and weldability, prepared by forming, on the surface of the steel plate, an alloy layer of 0.05 to 1.5μm thickness having a composition >=80% of which (Fe+Sn) comprises and a metallic coating composed of a tin-base alloy of 2.0 to 15.0μm thickness having a composition >=80% of which tin comprises and then forming, on the above metallic coating, an organic - inorganic combined coating containing one or more elements among Cr, Si, P, and Mn and having (0.01 to 2.0)g/m coating weight. Further, this steel plate is (2) a rust preventive steel plate for fuel tank, combining excellent workability, corrosion resistance, and weldability, in which, in addition to the characteristics of (1), the tin-base alloy consists of >=80% tin and the balance Zn, Mn, Cd, Al, Cr, Ti, and Mg.

Rust preventive pigment composition

Abstract: PURPOSE: To obtain a rust preventive pigment composition not generating any pollution and being superior in rust preventing performance. CONSTITUTION: This rust preventive pigment composition is composed of at least one kind phosphate compound selected from the group consisting of aluminum dihydrogen tripolyphosphate, zinc phosphate and aluminum metaphosphate, at least one kind divalent metallic oxide selected from the group consisting of zinc oxide and magnesium oxide and a phosphoric acid radical -containing talc. The composition ratio of the above-mentioned phosphate compound, time divalent metallic oxide and the phosphoric acid radical -containing talc is preferably 1:(0.20-1.25):(0.03-1.9) by weight.

Growth of leek rust epidemics in time in three cultivars during the early stage of the epidemic

Abstract: The growth of leek rust epidemics in time under favourable conditions in three leek cultivars during two years was analysed. In both years, the highest disease levels were found on cultivar Albana, followed by Carina and Cortina. A simple model is presented to correct the results for exchange of inoculum between adjacent plots. The results of this model indicate, that the difference in rust infection between the cultivars may be due to a reduced growth of the epidemic in young plants of cultivars Cortina and Carina. In older plants, the ranking in susceptibility was reversed, causing a less pronounced difference in infection between the cultivars. The growth of leek rust epidemics during the early stage of the epidemic in isolated plots was satisfactorily described by an exponential model.

Evaluation of Some Fungicides Against Rust and Black Spot in Rosa damascena cv. trigintipetala

Abstract: In the period 1985–1992, studies were conducted in field conditions on the efficiency of different fungicides against rust, Phragmidium mucronatum (Pers.) (Schlecht.) and black spot Diplocarpon rosae Wolf. of Rosa damascena cv. trigintipetala. The fungicides Baikor, Folicur plus Saprol and Impact proved to be most effective against both diseases. The results obtained could be used by farmers and co-operatives to control rust and black spot on oil-bearing roses.