scholarly journals Bioassay of Undisturbed Soil Cores for the Presence of Gaeumannomyces Graminis Var. Tritici

1973 ◽  
Vol 26 (6) ◽  
pp. 1267 ◽  
Author(s):  
GC Mac Nish ◽  
RL Dodman ◽  
NT Flentje
Keyword(s):  
Main Parameter ◽  
Gaeumannomyces Graminis ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Wheat Seedlings ◽  
The Core ◽  
Plant Remains ◽  
Undisturbed Soil Cores ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

The presence of viable G. graminis var. tritici in field soil was detected by a bioassay. Wheat seedlings were grown in undisturbed soil cores maintained under standard conditions for 4 weeks. The percentage of roots infected per core was the main parameter chosen to give an estimate of the level of G. graminis var. tritici inoculum in the core. Some variability between cores from the same site was observed, but this could be reduced by taking cores over plant remains within take-all patches. In this way, high and reasonably uniform levels of inoculum could be obtained to study the effect of various treatments on the incidence of G. graminis var. trifici.

scholarly journals Effect of Mixing and Sieving on Incidence of Gaeumannomyces Graminis Var. Tritici in Field Soil

1973 ◽  
Vol 26 (6) ◽  
pp. 1277 ◽  
Author(s):  
GC Mac Nish
Keyword(s):  
Surface Soil ◽  
Disease Incidence ◽  
Mesh Size ◽  
Gaeumannomyces Graminis ◽  
Soil Cores ◽  
Small Reduction ◽  
Undisturbed Soil ◽  
Soil Mixing ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

A bioassay was employed to compare the effect of various treatments on the level of G. graminis var. tritici inoculum in soil cores taken from a take-all patch. In a comparison of undisturbed soil and mixed soil, mixing caused a small reduction in incidence, possibly due to a dilution of the inoculum in the surface soil. Graded degrees of sieving from 5 to O� 5 mm mesh size caused a significant reduction in inoculum levels, with the latter reducing incidence to 3 % in seedlings at 4 weeks. However, it was also shown that increasingly finer sieving caused an increase in disease incidence if the seedlings were allowed to grow to maturity. It was not established whether the sieving affected the soil in such a way as to favour the pathogen, lower the resistance of the plant, or both.

Biological suppression of the saprophytic growth of Gaeumannomyces graminis var. tritici in soil

1987 ◽  
Vol 33 (6) ◽  
pp. 515-519 ◽  
Author(s):  
A. Simon ◽  
K. Sivasithamparam ◽  
G. C. MacNish
Keyword(s):  
Disease Severity ◽  
Gaeumannomyces Graminis ◽  
Seminal Root ◽  
Adjacent Area ◽  
Wheat Seedlings ◽  
Γ Radiation ◽  
Filter Membrane ◽  
History Of ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

The biological suppression of the saprophytic growth of Gaeumannomyces graminis var. tritici in soil in the absence of host roots appeared to be related to suppression of take-all disease of wheat seedlings. When soil collected from a plot which in 1984 and 1985 had grown wheat continuously for 7 and 8 years, respectively, was added at a level of 1% (w/w) to the same soil treated by γ-radiation, saprophytic growth of pigmented hyphae of G. graminis var. tritici on a filter membrane in a soil sandwich was suppressed relative to that occurring in irradiated soil. A soil of the same type from an adjacent area with a history of cereal–pasture alternate rotation did not significantly suppress saprophytic growth of G. graminis var. tritici. Biological suppression of disease of wheat caused by G. graminis var. tritici was tested in a pot bioassay by adding the same two soils, collected in 1985, at a level of 1% (w/w) to fumigated sand infested with oat kernels axenically colonized by the pathogen. Disease severity, measured as the percentage of the seminal root axes with discoloured stele, was reduced by 42 and 6% with the addition of continuous wheat and cereal–pasture rotation soils, respectively, to infested sand, compared with disease severity in unamended, infested sand alone.

scholarly journals Survival of Gaeumannomyces Graminis Var. Tritici in the Field Soil Stored In Controlled Environments

1973 ◽  
Vol 26 (6) ◽  
pp. 1319 ◽  
Author(s):  
GC Mac Nish
Keyword(s):  
Disease Incidence ◽  
Gaeumannomyces Graminis ◽  
Soil Cores ◽  
Field Soil ◽  
Controlled Environments ◽  
Significant Change ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

A bioassay was used to study the effect of various storage treatments on the survival of G. graminis var. tritici in soil cores removed from a take-all patch. There was no significant change in the incidence of the fungus when the soil was maintained either dry (-250 to -980 bars) and cool (15�C), or moist (-4'0 to -7,0 bars) and cool (15�C). When maintained very dry (-980 bars or less) and hot (35�C) or wet (-0'1 to -0,2 bar) and cool (15�C) there was a significant reduction in disease incidence, but considerable levels of viable fungus were still present after 45 weeks storage. Only in wet hot soil (-0'1 to -0,2 bar and 35�C) was the fungus eliminated rapidly.

Take-all, Gaeumannomyces graminis var. tritici, and yield of wheat grown after ley and arable rotations in relation to the occurrence of Phialophora radicicola var. graminicola

1979 ◽  
Vol 93 (2) ◽  
pp. 377-389 ◽  
Author(s):  
D. B. Slope ◽  
R. D. Prew ◽  
R. J. Gutteridge ◽  
Judith Etheridge
Keyword(s):  
Wheat Seedling ◽  
Gaeumannomyces Graminis ◽  
Wheat Crop ◽  
Soil Cores ◽  
Grassland Soils ◽  
Large Populations ◽  
The Difference ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Bio Assay ◽  
Take All

SUMMARYThe Rothamsted ley–arable experiments were on two fields with similar soils but with contrasting previous cropping: old grass on Highfield, old arable on Fosters field. Damage by take-all (Qaeumannomyces graminis var. tritici) occurred sooner in successive wheat crops grown after a lucerne ley and arable sequence (LU) than after a grass-clover ley and arable sequence (LC). On Highfield the difference was consistent and large, it occurred as soon as a second wheat crop was grown and resulted in wheat yielding 1 t/ha less after the LU than after the LC sequence. This difference did not persist in the next wheat crop where take-all was prevalent after both sequences. On Fosters field take-all developed more slowly and differences between sequences were mostly smaller.Wheat seedling bio-assay of soil cores from the LU and LC sequences showed that little take-all fungus persisted through the leys and that soils were much infested after a first wheat crop in the LU sequence on Highfield, but not in the LC sequence on Highfield or in either sequence on Fosters field. Microscopic examination of roots from assay seedlings and from field plants showed that Phialophora radicicola var. graminicola (PRG) was most common in soils where take-all developed slowly, but our results did not show if this was a causal relationship. The occurrence of much PRG in the LU sequence on Fosters conflicts with previous reports which associate large populations of this fungus only with grassland soils.

scholarly journals Pathogenicity of Gaeumannomyces graminis var tritici increased by nitrogen applied to soil to enhance the decomposition rate of wheat residues

2016 ◽  
Vol 69 ◽  
pp. 111-119
Author(s):  
R.F. Van_Toor ◽  
R.C. Butler ◽  
M. Braithwaite ◽  
D. Bienkowski ◽  
W. Qiu ◽  
...  
Keyword(s):  
Decomposition Rate ◽  
Dna Analysis ◽  
Crop Residues ◽  
Gaeumannomyces Graminis ◽  
Wheat Crop ◽  
Soil Cores ◽  
Wheat Seedlings ◽  
Soil Inoculum ◽  
Original Mass ◽  
Gaeumannomyces Graminis Var Tritici

Soil cores removed after harvest of a wheat crop infected with the fungus Gaeumannomyces graminis var tritici (Ggt) were amended with nitrogen and fungal saprophytes to increase decay of crop residues and subsequently reduce soil inoculum The cores were treated with one application of 50 kg nitrogen (N) per ha Trichoderma strains or both Cores were assessed 0 2 4 and 7 months after harvest At 7 months the crop residues had decayed to a third of their original mass with the decay not influenced by the treatments DNA analysis confirmed Ggt DNA was present in the stubble stems crowns and roots The pathogenicity of Ggt was increased by N as shown by a 5 to 8fold increase in takeall severity in indicator wheat seedlings planted in the Ntreated cores 2 to 4 months after harvest compared with those without N Ggt remained viable in all treatments to infect wheat seedlings 7 months after harvest

Effects of Certain Isolates of Bacteria and Actinomycetes on Gaeumannomyces graminis var. tritici and Take-All of Wheat

1978 ◽  
Vol 26 (6) ◽  
pp. 773 ◽  
Author(s):  
K Sivasithamparam ◽  
CA Parker
Keyword(s):  
Gaeumannomyces Graminis ◽  
Fluorescent Pseudomonads ◽  
Wheat Seedlings ◽  
Apparent Correlation ◽  
Test Organisms ◽  
Unsterile Soil ◽  
Shoot Weight ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

Five isolates each of actinomycetes, bacteria and fluorescent pseudomonads from the roots of wheat were tested for antagonism against Gaeumannomyces graminis var. tritici on agar and in sterile and unsterile soil. There was no apparent correlation between the tests. Effects on the growth of the take-all fungus (TAF) on agar ranged from nil to various degrees of colony deformation and/or inhibition. In a sterile sandy subsoil growing wheat seedlings, all except one isolate had no effect on disease production by a straw inoculum of the TAF. In an unsterile soil, however, measurements of shoot weight indicated that disease was reduced by all five isolates of bacteria singly and in mixture and by four of the five isolates of actinomycetes and a mixture of all five. Although a mixture of all five isolates of fluorescent pseudomonads reduced the disease, none of them produced a similar effect when tested singly. In the absence of the pathogen none of the test organisms significantly increased the shoot weight of wheat.

Evidence that each Rhizoctonia bare patch is dominated by an individual zymogram group (ZG) of Rhizoctonia solani AG-8

1993 ◽  
Vol 44 (6) ◽  
pp. 1175 ◽  
Author(s):  
GC MacNish ◽  
MW Sweetingham
Keyword(s):  
Rhizoctonia Solani ◽  
Western Australia ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Wheat Seedlings ◽  
Bare Patch ◽  
Infection Focus ◽  
Undisturbed Soil Cores

Studies of rhizoctonia bare patches in the southern part of the cereal belt of Western Australia indicate that each patch is dominated by an individual pectic zymogram group (ZG) of R. solani AG-8. R. solani was isolated from plants sampled from patches or from wheat seedlings grown in undisturbed soil cores removed from patches. The Rhizoctonia spp. isolated were characterized using electrophoresis in pectin-acrylamide gels. Four patch-forming zymogram groups (ZG1-1, ZG1-2. ZG1-4 and ZG1-5) were isolated. Of 121 patches examined, only five yielded more than one ZG. Two of these were due to the coalescing of two patches dominated by different zymogram groups. For the remaining three, there was only an occasional isolation of a ZG different from the dominant ZG. This may indicate a new infection focus endeavouring to establish in soil that another ZG occupies. Occasionally, patch-forming ZG1-1, ZG1-2, ZG1-4 and ZG1-5 were isolated from non-patch sites.

The use of zymogram and anastomosis techniques to follow the expansion and demise of two coalescing bare patches caused by Rhizoctonia solani AG-8

1993 ◽  
Vol 44 (6) ◽  
pp. 1161 ◽  
Author(s):  
GC MacNish ◽  
CK McLernon ◽  
DA Wood
Keyword(s):  
Rhizoctonia Solani ◽  
Growing Season ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Wheat Seedlings ◽  
Bare Patch ◽  
Apparent Death ◽  
Low Levels ◽  
Undisturbed Soil Cores

Pectic zymogram characterization and anastomosis techniques were used to study the distribution of strains of R. solani AG-8 in a large rhizoctonia bare patch. Undisturbed soil cores were removed on nine occasions during the period 1988 to 1992. Identification of the isolates of R. solani from wheat seedlings grown in the cores demonstrated that the patch was a coalescence of two patches, each colonized by isolates of R. solani AG-8 representing different zymogram groups (ZG1-1 and ZG1-5). The demarcation between the two patches remained unchanged while both patches were active. Between the 1989 and 1990 seasons, the pathogen in half of the ZG1-5 patch died, or was reduced to such low levels that it was difficult to detect. In the remainder of the ZG1-5 patch, the pathogen died or was reduced to undetectable levels between the 1990-91 seasons. The ZG1-1 patch was evident at the beginning of the 1991 growing season and the pathogen could be isolated; however, by the end of the season the pathogen could not be isolated. In all these instances the demise of the patch was associated with the disappearance of field symptoms and an inability to isolate the pathogen and therefore the apparent death of the fungus in the soil.

Isoproturon movement and dissipation in undisturbed soil cores from a grassed buffer strip

Agronomie ◽  
2000 ◽  
Vol 20 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Pierre Benoit ◽  
Enrique Barriuso ◽  
Philippe Vidon ◽  
Benoit Réal
Keyword(s):  
Soil Cores ◽  
Undisturbed Soil ◽  
Buffer Strip ◽  
Undisturbed Soil Cores
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