Aphanomyces Euteiches, a Cause of Root Rot of Subterranean Clover in Victoria.

1985 ◽  
Vol 14 (2) ◽  
pp. 34 ◽  
Author(s):  
FC Greenhalgh ◽  
PR Merriman ◽  
PJ Keane
Keyword(s):  
Root Rot ◽  
Subterranean Clover ◽  
Aphanomyces Euteiches

Bioassay and baiting methods for determining occurrence of races of Phytophthora clandestina in soil

1996 ◽  
Vol 36 (7) ◽  
pp. 815 ◽  
Author(s):  
A Purwantara ◽  
SP Flett ◽  
PJ Keane
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Subterranean Clover ◽  
Soil Samples ◽  
Field Soil ◽  
Flooded Soil ◽  
Aphanomyces Euteiches ◽  
Differential Cultivars ◽  
Pure Cultures ◽  
Race 1

The method currently used for determining races of Phytophthora clandestina requires isolation of pure cultures of the pathogen and testing of their pathogenicity on a range of differential cultivars. To date, the pathogen has not been isolated directly from soil and isolation of the pathogen from naturally infected seedlings is laborious. A bioassay involving the planting of differential cultivars in soil samples in small planting trays was developed to identify races of P. clandestina in soil. The specific races of the pathogen in the soil were determined by assessing the disease severity and the extent of sporulation of the pathogen on the roots of the differential cultivars. A more rapid baiting method using cotyledons of differential cultivars in flooded soil samples was also developed to determine the presence of different races in the samples. Both bioassays were used to confirm the presence of race 0 and race 1 in separate paddocks at Rutherglen, northern Victoria, over 4 seasons. The presence in field soil of another root rot pathogen of subterranean clover, Aphanomyces euteiches, was also detected using these techniques.

scholarly journals Identification of Pisum sativum Germ Plasm with Resistance to Root Rot Caused by Multiple Strains of Aphanomyces euteiches

Plant Disease ◽  
1999 ◽  
Vol 83 (1) ◽  
pp. 51-54 ◽  
Author(s):  
D. K. Malvick ◽  
J. A. Percich
Keyword(s):  
Pisum Sativum ◽  
Root Rot ◽  
Plant Introduction ◽  
Aphanomyces Euteiches ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Pea Seedlings ◽  
Biomass Loss ◽  
Serious Disease ◽  
Multiple Strains

Aphanomyces root rot is a serious disease of pea (Pisum sativum), and additional sources of resistance are needed for development of disease-resistant cultivars. Accessions (n = 123) from the P. sativum Plant Introduction (PI) collection with the highest relative levels of resistance to one strain of Aphanomyces euteiches were previously identified from among approximately 2,500 accessions evaluated. The chosen 123 accessions were evaluated in this study for resistance to root rot caused by multiple strains of this pathogen. Five strains representing different US geographical locations and pathogenicity characteristics were used to evaluate pea seedlings in a greenhouse. Disease severity (DS) and percent loss of fresh biomass (inoculated vs. non-inoculated plants) were determined 15 days after inoculation. Significant differences (P = 0.05) in levels of DS and biomass loss (BL) occurred among the accessions after inoculation individually with the five strains. The relative rank of accessions based on DS and BL varied with the strain of A. euteiches used for inoculations. The 20 accessions with the lowest DS after inoculation with each strain were identified. Based on lowest DS, two accessions were among the 20 identified with all five individual strains, and four other accessions were among the 20 identified with four of the five strains. The results suggest that the P. sativum PI collection contains useful accessions for breeding programs aimed at developing pea varieties with resistance to A. euteiches.

Aphanomyces euteiches. [Descriptions of Fungi and Bacteria].

1978 ◽  
Author(s):  
D. J. Stamps
Keyword(s):  
Population Dynamics ◽  
Geographical Distribution ◽  
Root Rot ◽  
Aphanomyces Euteiches ◽  
Conifer Seedlings ◽  
Alternative Hosts ◽  
Pea Root ◽  
Pea Root Rot ◽  
Sweet Pea

Abstract A description is provided for Aphanomyces euteiches. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Pea, Arabis, pansy, sweet pea, clover, bean, lupin, vetch, lucerne, Melilotus, barley, oats, Echinodorus brevipedicellatus. Conifer seedlings and other hosts were infected by inoculation. DISEASE: Root rot of pea. GEOGRAPHICAL DISTRIBUTION: Asia (Japan); Australia (Tasmania); Europe (UK, Denmark, France, Norway, Sweden, USSR); N. America (USA). (CMI Map 78, ed. 3, 1977). TRANSMISSION: Soil-borne, persisting in the soil for many years. Studies in Wisconsin suggested that A. euteiches may live as a weak parasite in the roots of many plants and occur naturally in some virgin soils (6, 523). Oospores were indicated to be the primary inocula for new outbreaks of pea root rot, zoospores the primary infective agents (39, 646). Survival between pea crops depended on oospore durability and possible alternative hosts, not saprophytic activity (41, 689). Studies were made of population dynamics in the soil (48, 2067) and penetration and infection of roots by zoospores (42, 287).

scholarly journals Associations among the communities of soil-borne pathogens, soil edaphic properties and disease incidence in the field pea root rot complex

2020 ◽  
Vol 457 (1-2) ◽  
pp. 339-354
Author(s):  
Kimberly Zitnick-Anderson ◽  
Luis E. del Río Mendoza ◽  
Shana Forster ◽  
Julie S. Pasche
Keyword(s):  
North Dakota ◽  
Root Rot ◽  
Prediction Models ◽  
Disease Incidence ◽  
Management Strategies ◽  
Clay Content ◽  
Field Pea ◽  
Aphanomyces Euteiches ◽  
Soil Borne Pathogens ◽  
Edaphic Properties

Abstract Background and aims Field pea production is greatly impacted by multiple soil-borne fungal and oomycete pathogens in a complex. The objectives of this research were to 1) identify the soil-borne pathogens associated with field pea in North Dakota and; 2) develop prediction models incorporating the occurrence of the soil-borne pathogen communities, soil edaphic properties and disease incidence. Methods Soil and plants were sampled from 60 field pea fields in North Dakota during 2014 and 2015. Plants (1500 across two years) were rated for both root rot and soil-borne pathogens isolated from roots. Soils were analyzed for edaphic properties. Indicator species analysis was used to identify soil-borne pathogen communities. Logistic regression was used to determine associations and develop prediction models. Results Survey results from 2014 and 2015 indicated that the most prevalent soil-borne pathogens identified in field pea fields were Fusarium spp. and Aphanomyces euteiches. Five soil-borne pathogen communities were identified; three of which had statistically significant associations characterized by (1) Fusarium acuminatum, (3) A. euteiches, and (4) Fusarium sporotrichioides. The occurrence of the three communities were associated with clay content, soil pH, Fe2+, and K+. Disease incidence was associated with the presence of either community 1 or 3 and K+. Conclusions The results generated from this research will contribute to the development of management strategies by providing a soil-borne pathogen community prediction tool.

The in vitro inhibition of Phytophthora clandestina by some rhizobia and the possible role of Rhizobium trifolii in biological control of Phytophthora root rot of subterranean clover

1999 ◽  
Vol 50 (8) ◽  
pp. 1469 ◽  
Author(s):  
S. Simpfendorfer ◽  
T. J. Harden ◽  
G. M. Murray
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Root Disease ◽  
Rhizobium Trifolii ◽  
Biological Control Agents ◽  
Control Activity ◽  
Phytophthora Root Rot

The interaction between 29 isolates of Rhizobium and the in vitro growth of 3 strains of Phytophthora clandestina was investigated to determine the potential of these bacteria as biological control agents against root rot of subterranean clover (Trifolium subterraneum L.). The biological control activity of Rhizobium on the severity of root disease in seedlings was also investigated under glasshouse conditions. Thirteen of the 29 Rhizobium isolates caused significant reductions in the hyphal growth of the 3 P. clandestina isolates examined. Inoculation of seedlings with Rhizobium trifolii reduced the severity of root disease by 14–58% with corresponding increases in dry matter production of 20–73%. These results indicate that Rhizobium species have potential as biological control agents against the root rot of T. subterraneum seedlings caused by P. clandestina.

Response of Aphanomyces euteiches mycelia, zoospore, and oospore to oat extract

2004 ◽  
Vol 84 (2) ◽  
pp. 687-690
Author(s):  
M. A. Chandler ◽  
V. A. Fritz ◽  
R. R. Allmaras
Keyword(s):  
Pisum Sativum ◽  
Root Rot ◽  
Green Manure ◽  
Mycelial Growth ◽  
Late Summer ◽  
Aphanomyces Euteiches ◽  
Economic Threat ◽  
Pisum Sativum L ◽  
Production Research ◽  
Reduce Disease Severity

Root rot (Aphanomyces euteiches Drechs.) is a serious economic threat to pea (Pisum sativum L.) production. Research has shown a late-summer-seeded oat (Avena sativa L .) crop can reduce disease severity. A. euteiches was exposed to extracts of oat cvs. Bay and Ogle. Oat extract significantly enhanced mycelial growth of the pathogen. Key words: Root rot, biological control, green manure, Pisum sativum

Infection of seed of subterranean clover and allied species by species of Fusarium

1980 ◽  
Vol 31 (2) ◽  
pp. 297 ◽  
Author(s):  
AW Kellock ◽  
LL Stubbs ◽  
DG Parbery
Keyword(s):  
Root Rot ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Scar Tissue ◽  
Seed Infection ◽  
Fusarium Spp ◽  
Blotting Paper ◽  
Optical Brighteners ◽  
First Time ◽  
Healthy Seed

Fusarium avenaceurn (Corda ex Fr.) Sacc. was shown for the first time to be carried in the hilum of subterranean clover (Trifolium Subterraneum L.) seed. Scanning electron microscopy and thin-section techniques showed that the fungus occurred only as dormant mycelium in parenchyma cells of funicle scar tissue. It emerged from these tissues after a 12 h incubation at 24�C and in 48 h penetrated internal parts of the seed through the hilum fissure. After 21 days on moist blotting paper, seedlings grown from infected seed developed lesions on their roots similar to those of root-rot of subterranean clover in the field. Fusarium spp. were also detected in the hilum of seeds of white (T. repens L.) and strawberry (T. fragiferum L.) clover and barrel medic (M. truncatula L.). It was demonstrated experimentally that all parts of the burr, incl~tding the funicle, became infected with F. avenaceuni when subterranean clover plants grown from healthy seed in pasteurized soil buried their burrs in soil inoculated with the fungus. Use of optical brighteners failed to trace seed infection because the compounds, although absorbed by the pathogen in culture, were not translocated.

Severity of root rot in mature subterranean clover and associated fungal pathogens in the wheatbelt of Western Australia

2009 ◽  
Vol 60 (1) ◽  
pp. 43 ◽  
Author(s):  
Tiernan A. O'Rourke ◽  
Tim T. Scanlon ◽  
Megan H. Ryan ◽  
Len J. Wade ◽  
Alan C. McKay ◽  
...  
Keyword(s):  
Western Australia ◽  
Root Rot ◽  
Fungal Pathogens ◽  
Lateral Roots ◽  
Subterranean Clover ◽  
Growing Season ◽  
Root Diameter ◽  
Root Disease ◽  
Soil Dna ◽  
Tap Root

Pasture decline is considered to be a serious challenge to agricultural productivity of subterranean clover across southern Australia. Root disease is a significant contributing factor to pasture decline. However, root disease assessments are generally carried out in the early part of the growing season and in areas predominantly sown to permanent pastures. For this reason, in spring 2004, a survey was undertaken to determine the severity of root disease in mature subterranean clover plants in pastures located in the wheatbelt of Western Australia. DNA-based soil assays were used to estimate population density in the soil of a variety of soil-borne pathogens known to commonly occur in the Mediterranean-type environments of southern Australia. The relationships between severity of disease on tap and lateral roots and root diameter, root length, nodulation, and total rainfall were determined. The survey showed, for the first time, that severe root disease is widespread in spring across the wheatbelt of Western Australia. There was a positive correlation between rainfall and tap root disease, and between tap root disease and average root diameter of the entire root system. Despite the high levels of root disease present across the sites, the DNA of most root disease pathogens assayed was detected in trace concentrations. Only Pythium Clade F showed high DNA concentrations in the soil. DNA concentrations in the soil, in particular for Phytophthora clandestina and Rhizoctonia solani AG 2.1 and AG 2.2, were higher in the smaller autumn sampling in 2006. This study suggests that the productivity of subterranean clover-based pastures is severely compromised by root rot diseases throughout the growing season in the wheatbelt of Western Australia.

Occurrence of Phytophthora clandestina in Trifolium subterraneum paddocks in Australia

2001 ◽  
Vol 41 (2) ◽  
pp. 187 ◽  
Author(s):  
R. Aldaoud ◽  
W. Guppy ◽  
L. Callinan ◽  
S. F. Flett ◽  
K. A. Wratten ◽  
...  
Keyword(s):  
Western Australia ◽  
Root Rot ◽  
New South ◽  
New South Wales ◽  
South Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Soil Samples ◽  
South Wales ◽  
Differential Cultivars

In 1995–96, a survey of soil samples from subterranean clover (Trifolium subterraneum L.) paddocks was conducted across Victoria, South Australia, New South Wales and Western Australia, to determine the distribution and the prevalence of races of Phytophthora clandestina (as determined by the development of root rot on differential cultivars), and the association of its occurrence with paddock variables. In all states, there was a weak but significant association between P. clandestina detected in soil samples and subsequent root rot susceptibility of differential cultivars grown in these soil samples. Phytophthora clandestina was found in 38% of the sampled sites, with a significantly lower prevalence in South Australia (27%). There were significant positive associations between P. clandestina detection and increased soil salinity (Western Australia), early growth stages of subterranean clover (Victoria), mature subterranean clover (South Australia), recently sown subterranean clover (South Australia), paddocks with higher subterranean clover content (Victoria), where herbicides were not applied (South Australia), irrigation (New South Wales and Victoria), cattle grazing (South Australia and Victoria), early sampling dates (Victoria and New South Wales), sampling shortly after the autumn break or first irrigation (Victoria), shorter soil storage time (Victoria) and farmer’s perception of root rot being present (Victoria and New South Wales). Only 29% of P. clandestina isolates could be classified under the 5 known races. Some of the unknown races were virulent on cv. Seaton Park LF (most resistant) and others were avirulent on cv. Woogenellup (most susceptible). Race 1 was significantly less prevalent in South Australia than Victoria and race 0 was significantly less prevalent in New South Wales than in South Australia and Western Australia. This study revealed extremely wide variation in the virulence of P. clandestina. The potential importance of the results on programs to breed for resistance to root rot are discussed. in South Australia.

Sign in / Sign up

Export Citation Format

Share Document