scholarly journals Incidence of Gaeumannomyces Graminis Var. Tritici in Consecutive Wheat Crops

1973 ◽  
Vol 26 (6) ◽  
pp. 1301 ◽  
Author(s):  
GC Mac Nish ◽  
RL Dodman

A mapping technique based on an "incidence-yield" regression was used to study the incidence of G. graminis var. tritici in consecutive wheat crops at two locations in South Australia. At both locations there were only small differences between the two years, although at Turretfield (third and fourth crops) there was a tendency for highincidence areas to contract, while at Ceduna (second and third crops) disease incidence tended to increase.

1991 ◽  
Vol 31 (4) ◽  
pp. 509 ◽  
Author(s):  
DK Roget ◽  
AD Rovira

. This paper describes results obtained from an 8-year field trial on a calcareous sandy loam in South Australia. Different crop rotations resulted in varying percentages of plants with take-all [caused by Gaeumannomyces graminis var. tritici (Ggt)]. The results demonstrated that in a wheat-grass/medic pasture rotation, take-all caused an average annual yield loss in wheat of 29%. These yield losses were strongly correlated with disease incidence and rainfall in September (r2 = 0.91, P = 0.07) but only moderately correlated to disease incidence alone (r2 = 0.44, P = 0.09). The level of early infection (at 10 weeks) by Ggt was influenced by spring rainfall in the previous season. A regression model was developed to predict the incidence of take-all in a wheat crop from the incidence of take-all and the August-September rainfall the previous season (r2 = 0.96, P = 0.007) for a wheat-grass/medic pasture rotation (successive host plants).


1973 ◽  
Vol 26 (6) ◽  
pp. 1277 ◽  
Author(s):  
GC Mac Nish

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.


1973 ◽  
Vol 26 (6) ◽  
pp. 1319 ◽  
Author(s):  
GC Mac Nish

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.


1987 ◽  
Vol 27 (3) ◽  
pp. 419 ◽  
Author(s):  
JF Kollmorgen ◽  
PE Ridge ◽  
RFde Boer

In 4 trials in the Northern Wimmera of Victoria, the incidence and severity of take-all of wheat caused by Gaeumannomyces graminis var. tritici were generally unaffected by tillage treatments (nil, chemical weed control; subsurface, blade plough and rod weeder; conventional scarifier, cultivator and harrows). At 1 site at 1 sampling time disease incidence was higher after conventional tillage than after subsurface tillage and at another site in 1 year out of 3, disease severity was greater after nil tillage than after conventional tillage. A stubble mulch of 4 t ha-1 of straw and burial at 5 or 10 cm reduced survival of the take-all fungus in wheat crowns.


1989 ◽  
Vol 29 (2) ◽  
pp. 247 ◽  
Author(s):  
RF Brennan

Wheat was grown in soil amended with 5 levels of superphosphate with or without 4 levels of flutriafol at 3 sites naturally infested with Gaeumannomyces graminis var. tritici. The severity of take-all was related to the rates of superphosphate and flutriafol. At all sites, the disease incidence and severity were high, with values for the moderate plus severe category (i.e. >25% of the root system discoloured by the takeall fungus) exceeding 80% for untreated plots. As plants responded to increasing levels of superphosphate and flutriafol, the percentage of infected roots declined. There was no further decline in the severity of take-all with increasing levels of flutriafol above 50 g/ha. The lowest severity of take-all was observed at the highest superphosphate level (200 kg/ha) and a fungicide level of 50 g/ha. Take-all severity for this treatment varied with the site location, being 52% at Condingup while the Mt Ridley and Neridup sites had 60% infection of take-all on the roots. There was a 25-30% increase in grain yield in response to added flutriafol at the highest superphosphate level. There were also corresponding increases in dry matter production and 1000-grain weights with superphosphate and fungicide application.


1973 ◽  
Vol 26 (6) ◽  
pp. 1285 ◽  
Author(s):  
GC Mac Nish

Two methods (visual assessment and a bioassay) of detecting the presence of G. graminis var. tritici in wheat stubble were compared. Of the stubble visually assessed as infected, only 4 % was not confirmed as infected by the bioassay. On the other hand, the bioassay showed that 41 % of the stubble visually assessed as free of infection was incorrectly assigned.


2010 ◽  
Vol 100 (5) ◽  
pp. 404-414 ◽  
Author(s):  
Youn-Sig Kwak ◽  
Peter A. H. M. Bakker ◽  
Debora C. M. Glandorf ◽  
Jennifer T. Rice ◽  
Timothy C. Paulitz ◽  
...  

Dark pigmented fungi of the Gaeumannomyces–Phialophora complex were isolated from the roots of wheat grown in fields in eastern Washington State. These fungi were identified as Phialophora spp. on the basis of morphological and genetic characteristics. The isolates produced lobed hyphopodia on wheat coleoptiles, phialides, and hyaline phialospores. Sequence comparison of internal transcribed spacer regions indicated that the Phialophora isolates were clearly separated from other Gaeumannomyces spp. Primers AV1 and AV3 amplified 1.3-kb portions of an avenacinase-like gene in the Phialophora isolates. Phylogenetic trees of the avenacinase-like gene in the Phialophora spp. also clearly separated them from other Gaeumannomyces spp. The Phialophora isolates were moderately virulent on wheat and barley and produced confined black lesions on the roots of wild oat and two oat cultivars. Among isolates tested for their sensitivity to 2,4-diacetylphloroglucinol (2,4-DAPG), the 90% effective dose values were 11.9 to 48.2 μg ml–1. A representative Phialophora isolate reduced the severity of take-all on wheat caused by two different isolates of Gaeumannomyces graminis var. tritici. To our knowledge, this study provides the first report of an avenacinase-like gene in Phialophora spp. and demonstrated that the fungus is significantly less sensitive to 2,4-DAPG than G. graminis var. tritici.


Author(s):  
J. Walker

Abstract A description is provided for Gaeumannomyces graminis var. tritici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Gramineae, especially Triticum, Hordeum, Secale, Agropyron and several other grass genera and, more rarely, Sorghum and Zea; also recorded from the roots of plants in other families. DISEASE: Take-all of cereals and grasses (also referred to as deadheads or whiteheads, pietin and pied noir (France), Schwarzbeinigkeit and Ophiobolus Fusskrankheit (Germany), Ophiobolusvoetziekt (Netherlands) and others). Root infection is favoured by soil temperature from 12-20°C (Butler, 1961). Ascospore germ tubes penetrate root hairs and the epidermis in the meristematic region (Weste, 1972) leading to plugging of xylem and root death. GEOGRAPHICAL DISTRIBUTION: (CMI Map 334, ed. 3, 1972). Widespread, especially in temperate zones. Africa; Asia (India, Iran, Japan, USSR): Australasia and Oceania; Europe; North America (Canada, USA); South America (Argentina, Brazil, Chile, Colombia, Uruguay). TRANSMISSION: In soil on infected organic fragments, as runner hyphae on roots of cereals and grasses and, under special conditions, by ascospores. Seed transmission very doubtful (47, 3058).


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