Reaction of soybean cultivars to races of Phytophthora megasperma f.sp. glycinea present in Queensland

1982 ◽  
Vol 33 (5) ◽  
pp. 763 ◽  
Author(s):  
JL Rose ◽  
JAG Irwin ◽  
MJ Ryley ◽  
PW Langdon ◽  
LB Jenner
Keyword(s):  
Disease Incidence ◽  
Field Resistance ◽  
The Other ◽  
Stem Rot ◽  
Breeding Line ◽  
Phytophthora Megasperma ◽  
Breeding Lines ◽  
The North ◽  
Race 1 ◽  
Race 2

Phytophthora megasperma f.sp, glycinea, the cause of phytophthora root and stem rot of soybeans, was found to be widespread in southern Queensland. Race determinations on 56 isolates were made at 26�C using the North American differential set. Thirty isolates resembled race 1 (virulent only on Harosoy), while the remaining isolates killed varying proportions of the other six differentials. Two of these isolates most closely resembled race 15. When race determinations were repeated for four isolates at 31�C, each isolate was more virulent on most of the differentials. One isolate resembling race 1 at 26�C would have been classified as race 2 at 31�C. All of the cultivars grown in Queensland were susceptible to hypocotyl inoculation, indicating the absence of genes conditioning resistance to races 1 and 15. Small proportions of plants in some cultivars, including Davis and Bragg were resistant to hypocotyl inoculation. The field resistances of 21 cultivars and breeding lines were assessed in a disease nursery. Progressive assessments of disease incidence were significantly correlated with grain yield and plant height. Davis had the highest level of field resistance while Ross and Semstar had the lowest. A breeding line (HS 1115) was identified as highly resistant to the fungus, both in the field and following hypocotyl inoculation. Three F6 lines from the cross Davis x Bragg showed a range of disease reactions, with the best showing an equivalent level of resistance to that of Davis.

scholarly journals DISTRIBUTION AND RACE COMPOSITION OF DOWNY MILDEW (Plasmopara halstedii (Farl.) Berl. and de Toni) IN BULGARIA / EXTENSION Y RAZAS DEL MILDIU (Plasmopara halstedii (Farl.) Berl. y de Toni) EN BULGARIA / ÉTENDUE ET RACES DE LA ROUILLE (Plasmopara halstedii (Farl.) Berl. and de Toni) EN BULGARIE

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 25-32
Author(s):  
P.S. Shindrova
Keyword(s):  
Downy Mildew ◽  
Resistance Gene ◽  
The Other ◽  
Plasmopara Halstedii ◽  
North West ◽  
North East ◽  
Race 1 ◽  
Race 2 ◽  
Production Areas ◽  
Number Of Authors

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.

scholarly journals Reaction of Select Peanut (Arachis hypogaea L.) Lines to Southern Stem Rot and Pythium Pod Rot Under Varied Disease Pressure

1989 ◽  
Vol 16 (1) ◽  
pp. 9-14 ◽  
Author(s):  
O. D. Smith ◽  
T. E. Boswell ◽  
W. J. Grichar ◽  
C. E. Simpson
Keyword(s):  
Arachis Hypogaea ◽  
Disease Incidence ◽  
Sclerotium Rolfsii ◽  
Stem Rot ◽  
Resistant Parent ◽  
Breeding Lines ◽  
Arachis Hypogaea L ◽  
Significant Yield ◽  
Considerable Resistance ◽  
Disease Pressure

Abstract Eight breeding lines, three parents, and the cultivar Florunner were compared under two levels of disease pressure induced by Sclerotium rolfsii Sacc., or Pythium myriotylum Drechs. at each of two locations for three years to ascertain the effectiveness of the host plant resistance to each pathogen. Varied disease pressures were created by application of fungicides and supplement of fungal inoculum. Mean Florunner pod yields varied more than 1000 kg/ha as a result of the S. rolfsii treatments but the yields of the resistant TxAG-3 were not affected. Disease incidence, as measured by frequency of S. rolfsii infection sites and diseased pods, was much higher for Florunner than TxAG-3. Breeding lines for which TxAG-3 was a parent sustained significant yield reductions. The disease incidence in these lines was higher than the resistant parent, equal or less than Tamnut 74, their other parent, and less than Florunner. The grades of TxAG-3 and its derivatives were lower than Florunner. Pod rot incidence differed for the P. myriotylum treatments but pod yields were not different. TxAG-3 and Toalson sustained less pod disease than Florunner and Tamnut 74. The percent of diseased pod tissue for one derivative of Toalson was lower than Toalson and TxAG-3, and that of one TxAG-3 derivative was equal to its best parent. The breeding lines varied in reaction to the two diseases and some lines showed considerable resistance to both organisms.

Resistance to race 1 of Kabatiella caulivora in subterranean clover (Trifolium subterraneum L.) cultivars and breeding lines

2008 ◽  
Vol 59 (6) ◽  
pp. 561 ◽  
Author(s):  
P. G. H. Nichols ◽  
M. P. You ◽  
M. J. Barbetti
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Breeding Lines ◽  
Race 1 ◽  
Kabatiella Caulivora ◽  
Selection For ◽  
Race 2 ◽  
Resistant Progeny ◽  
Clover Scorch

Twenty-eight cultivars and 106 F6-derived breeding lines of subterranean clover (Trifolium subterraneum) were screened in the field for their response to clover scorch disease caused by race 1 of Kabatiella caulivora. Eleven of the cultivars, including Denmark and Goulburn, were classified as resistant. Breeding lines with Denmark parentage had 55% of progeny with resistance, while those of Goulburn had only 19% of resistant progeny, suggesting different modes of inheritance. Selection for resistance to race 2 of K. caulivora in the F4 generation markedly increased the probability of selecting F6-derived lines with resistance to race 1, suggesting linkage between genes for resistance to both races.

scholarly journals Suppression of Fusarium Wilt Caused by Fusarium oxysporum f. sp. niveum Race 2 on Grafted Triploid Watermelon

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1326-1332 ◽  
Author(s):  
Anthony P. Keinath ◽  
Richard L. Hassell
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Disease Incidence ◽  
The United States ◽  
Infested Soil ◽  
Marketable Yield ◽  
Race 1 ◽  
Susceptible Control ◽  
Triploid Watermelon ◽  
Race 2

Fusarium wilt of watermelon, caused by the soilborne fungal pathogen Fusarium oxysporum f. sp. niveum race 2, is a serious, widespread disease present in major watermelon-growing regions of the United States and other countries. ‘Fascination,’ a high yielding triploid resistant to race 1, is grown in southeastern states in fields that contain a mixture of races 1 and 2. There is some benefit to using cultivars with race 1 resistance in such fields, even though Fascination is susceptible to Fusarium wilt caused by race 2. Experiments in 2012 and 2013 were done in fields infested primarily with race 2 and a mixture of races 1 and 2, respectively. Fascination was grafted onto four rootstock cultivars: bottle gourd (Lagenaria siceraria) ‘Macis’ and ‘Emphasis’ and interspecific hybrid squash (Cucurbita maxima× C. moschata) ‘Strong Tosa’ and ‘Carnivor.’ Nongrafted and self-grafted Fascination were used as susceptible control treatments. In both experiments, mean incidence of plants with symptoms of Fusarium wilt was ≥52% in the susceptible control treatments and ≤6% on the grafted rootstocks. Disease incidence did not differ between rootstock species or cultivars. In both years, Fascination grafted onto Strong Tosa and Macis produced more marketable-sized fruit than the susceptible control treatments. Grafted Emphasis and Carnivor also produced more fruit than the control treatments in 2012. The cucurbit rootstocks suppressed Fusarium wilt caused by race 2 and increased marketable yield of triploid watermelon grown in infested soil.

Effect of Phytophthora root and stem rot on the response of field-grown soybean to Saturated Soil Culture

1991 ◽  
Vol 42 (5) ◽  
pp. 791 ◽  
Author(s):  
RJ Troedson ◽  
MJ Ryley ◽  
DE Byth ◽  
JAG Irwin
Keyword(s):  
Field Resistance ◽  
Saturated Soil ◽  
Stem Rot ◽  
Soil Culture ◽  
Phytophthora Megasperma ◽  
High Soil Moisture ◽  
High Level ◽  
The Impact ◽  
Extent Of Disease ◽  
Important Disease

Phytophthora root and stem rot, caused by Phytophthora megasperma Drechs. f. sp. Glycinea Kuan & Erwin, is an important disease of soybean in several major growing areas across the world. Susceptible genotypes can be completely devastated, but cultivars with a high level of field resistance are available. Although high soil moisture is known to predispose to infection by Phytophthora, in the absence of this disease soybean is relatively tolerant to soil waterlogging, and has been shown to respond positively to continuous watering in the Saturated Soil Culture (SSC) system. The impact of Phytophthora on plants grown in SSC was investigated at two sites in south-east Queensland. At both sites, there were no differences between plants grown in SSC and conventional furrow-irrigated treatments in the rate or ultimate extent of disease development: susceptible cultivars succumbed to the disease, while cultivars with field resistance remained free of symptoms. A fungicidal seed dressing improved emergence and reduced initial disease infection, and improved seed yield in some cultivars. It was concluded that Phytophthora root and stem rot is not a limitation to the use of Saturated Soil Culture in soybean providing resistant cultivars are available.

scholarly journals Control of Fusarium Wilt of Watermelon by Grafting onto Bottlegourd or Interspecific Hybrid Squash Despite Colonization of Rootstocks by Fusarium

Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 255-266 ◽  
Author(s):  
A. P. Keinath ◽  
R. L. Hassell
Keyword(s):  
Fusarium Wilt ◽  
Interspecific Hybrid ◽  
Citrullus Lanatus ◽  
Disease Incidence ◽  
Field Performance ◽  
Control Treatment ◽  
Infested Field ◽  
Race 1 ◽  
Seedless Watermelon ◽  
Race 2

Grafting watermelon (Citrullus lanatus var. lanatus) onto rootstocks of interspecific hybrid squash (Cucurbita moschata × C. maxima), bottle gourd (Lagenaria siceraria), or citron (Citrullus lanatus var. citroides) has been used in Asia and Israel to mange Fusarium wilt of watermelon caused by Fusarium oxysporum f. sp. niveum. The objectives of this study were to determine the frequency of infection of six rootstocks by F. oxysporum f. sp. niveum races 1 and 2 and the field performance of grafted rootstocks in Charleston, SC. Grafted and nongrafted watermelon and rootstock plants were inoculated in the greenhouse with race 1, race 2, or water (the control treatment). With both races, the frequency of recovery of F. oxysporum from scion and rootstock portions of inoculated watermelon plants grafted onto ‘Ojakkyo’ citron was greater than from watermelon plants grafted onto ‘Shintosa Camel’ and ‘Strong Tosa’ interspecific hybrid squash, and from plants grafted onto ‘Emphasis’, ‘Macis’, and ‘WMXP 3945’ bottlegourd. For nongrafted plants inoculated with race 1, percent recovery also was greater from Ojakkyo than from interspecific hybrid squash and bottlegourd. For nongrafted plants inoculated with race 2, F. oxysporum was recovered from the base of ≥79% of all inoculated plants. More than two-thirds (15) of 21 isolates recovered from the tops or scions of inoculated plants were pathogenic on watermelon. In spring 2010 and 2011, the six rootstocks were grafted with seedless watermelon ‘Tri-X 313’, which is susceptible to both races, and transplanted in a field infested with races 1 and 2 of F. oxysporum f. sp. niveum. Disease incidence for nongrafted and self-grafted Tri-X 313 (the control treatments) and Tri-X 313 grafted onto Ojakkyo citron did not differ significantly. Grafted watermelon plants produced greater weights and numbers of fruit than plants of the two control treatments. Nonpathogenic isolates of F. oxysporum and isolates of F. oxysporum f. sp. niveum colonized interspecific hybrid squash, bottlegourd, and grafted watermelon. The rootstocks evaluated, however, restricted movement of F. oxysporum f. sp. niveum into the watermelon scion, suppressed wilt symptoms, and increased fruit yields in an infested field.

Reaction of Selected Peanut Varieties and Breeding Lines to Southern Stem Rot1

1997 ◽  
Vol 24 (1) ◽  
pp. 6-9 ◽  
Author(s):  
B. A. Besler ◽  
W. James Grichar ◽  
O. D. Smith
Keyword(s):  
Disease Resistance ◽  
West Africa ◽  
Burkina Faso ◽  
Disease Incidence ◽  
Sclerotium Rolfsii ◽  
Field Conditions ◽  
Breeding Line ◽  
Breeding Lines ◽  
Yield Increase

Abstract Eight Texas and one Georgia breeding lines, four accessions from Burkina Faso (West Africa), and six runner and two spanish-type cultivars were compared for yield, grade, and susceptibility to Sclerotium rolfsii Sacc. for 3 yr under irrigated field conditions. The spanish-type cultivar Tamspan 90 and runner-type breeding line TX896100 (recently released as Tamrun 96) consistently had the lowest disease incidence for all 3 yr. Averaged over years, TX896100 was the highest yielding entry. Four breeding lines resulted in a 2 to 16% yield increase over Okrun, the highest yielding cultivar. The African accessions, in general, produced low yields and low grades with no advantages in disease resistance.

scholarly journals Distribution and Pathogenic Characterization of Pyrenophora tritici-repentis and Stagonospora nodorum in Ohio

2006 ◽  
Vol 96 (12) ◽  
pp. 1355-1362 ◽  
Author(s):  
Jessica S. Engle ◽  
Laurence V. Madden ◽  
Patrick E. Lipps
Keyword(s):  
Linear Analysis ◽  
The Other ◽  
Stagonospora Nodorum ◽  
Pyrenophora Tritici Repentis ◽  
Logistic Analysis ◽  
Wheat Leaf ◽  
Race 1 ◽  
Race 2 ◽  
Log Linear

To determine the distribution of Stagonospora nodorum and Pyrenophora tritici-repentis on wheat in Ohio, flag leaves with lesions were collected from wheat-producing counties in 2002 and 2003. Counties were arbitrarily grouped into seven regions. Log-linear analysis of pathogen presence within regions indicated that the presence of S. nodorum was independent of the presence of P. tritici-repentis. A logistic analysis revealed that the occurrence of both pathogens varied by region in one or both years. The aggressiveness of S. nodorum isolates was determined by inoculating two susceptible genotypes with a subsample of isolates from each region from both years. S. nodorum isolates obtained from northeast Ohio, with fewer wheat fields, were less aggressive than those from other regions. Isolates obtained from west-central Ohio, surrounded by regions with high wheat production annually, were significantly more aggressive than those obtained in the remaining five regions. Isolates from the five other regions did not differ significantly (P > 0.05) in aggressiveness. Races 1 and 2, and a few race 3 isolates, of P. tritici-repentis were detected in Ohio. The distribution of P. tritici-repentis races 1 and 2 was not associated with any region, although the prevalence of race 1 was three times greater than race 2. The rarer race 3 was associated with three dispersed regions. Results indicate that S. nodorum was the major wheat leaf-blotching pathogen. There were no positive or negative associations of S. nodorum and P. tritici-repentis or individual races of P. tritici-repentis in any of the tested regions, which indicates that neither pathogen can be used to predict the presence of the other. The isolated northeastern corner of Ohio appeared to contain isolates of S. nodorum with unique characteristics and potentially only one race of P. tritici-repentis, indicating that this area may be genetically isolated from the remaining tested areas of the state.

Glasshouse and field screening of chickpea cultivars for resistance to Phytophthora megasperma f.sp. medicaginis

1991 ◽  
Vol 31 (5) ◽  
pp. 663 ◽  
Author(s):  
ML Dale ◽  
JAG Irwin
Keyword(s):  
Disease Incidence ◽  
Field Trials ◽  
Field Resistance ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Progress Curve ◽  
Susceptible Control ◽  
Epidemic Development ◽  
Compound Interest ◽  
Chickpea Cultivars

The resistance expressed by a range of chickpea cultivars to phytophthora root rot in glasshouse and field trials was examined. Van der Plank's compound interest equation was the most suitable transformation for providing parameters to describe epidemic development for most of the cultivars when compared to the simple interest equation by plotting residuals and coefficients of determination. The area under the disease progress curve (AUDPC) was significantly correlated with the final disease incidence (FDI), which was also significantly correlated with the apparent infection rate (r), but r and AUDPC were not significantly correlated. The AUDPC proved to be relatively indiscriminate in this study for selecting resistant cultivars, since the value for the susceptible control cultivar was high, and many cultivars therefore had statistically lower AUDPC values. Several cultivars (i.e. CQ1591, ICC7568 and 232-4) were resistant on the basis of both the FDI and r parameters in the field trial and considered worthy of further investigation. When the parameters FDI or r were used to categorise the disease reactions of cultivars in the field, only half of the 30 cultivars assessed showed similar responses in both the glasshouse and field trials. The glasshouse assay used here does not allow the detection of all potentially useful forms of field resistance, and further work is needed in the development of a glasshouse assay which gives an accurate representation of field response to Phytophthora megasperma Drechs. f. sp. medicaginis Kuan and Erwin.

Variability within Kabatiella caulivora Race 1 and Race 2 revealed by cultural and molecular analyses

2003 ◽  
Vol 54 (1) ◽  
pp. 77 ◽  
Author(s):  
K. L. Bayliss ◽  
L. Spindler ◽  
E. S. Lagudah ◽  
K. Sivasithamparam ◽  
M. J. Barbetti
Keyword(s):  
Aflp Analysis ◽  
Similarity Coefficients ◽  
Breeding Lines ◽  
Disease Site ◽  
Race 1 ◽  
Kabatiella Caulivora ◽  
Race Comparison ◽  
New Races ◽  
Race 2 ◽  
Clover Scorch

Kabatiella caulivora is the causal agent of clover scorch, a fungal disease of clover (Trifolium) species. Variability within and between K. caulivora Race 1 and Race 2 was determined by cultural characteristics, isozymes, and amplified fragment length polymorphisms (AFLP). Cultural studies indicated isolates from both races were highly variable. No differences were identified within or between races by isozyme analysis. Similarity coefficients, determined from AFLP analysis, indicated that isolates from different races were often more similar than isolates from the same race. Comparison of single representative isolates from Race 1 and Race 2, collected at a Denmark (Western Australia) disease site, with isolates collected from another site of clover scorch outbreak at Esperance, 300 km east of Denmark, indicated most of the isolates causing the second outbreak were similar to Race�2, confirming previously conducted pathogenicity tests. It is hypothesised that Race 2 may have evolved from Race 1, and that the level of variability in the pathogen indicates the potential for development of further new races of K. caulivora. The requirement for improved selection strategies, including the screening of new cultivars and breeding lines with multiple isolates of the pathogen, is discussed in relation to these findings.

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