Survival of the take-all fungus in the presence and absence of susceptible grasses

Soil Research ◽  
1988 ◽  
Vol 26 (2) ◽  
pp. 313 ◽  
Author(s):  
PJ Cotterill ◽  
K Sivasithamparam

A field trial was conducted to compare the effect of depth on inoculum of Gaeumannomyces graminis var. tritici under grasses and bare-fallow. Soil was sampled from 0-5, 5-10 and 10-15 cm depths in March, October and December 1986. Sample bioassays were carried out to determine infectivity, propagule number and to evaluate the contribution of different sized particles to the total soil-borne inoculum. A pot experiment examined the conduciveness of the respective soil samples to take-all. Grasses were effective in the carry-over of the field inoculum of the take-all fungus. In grass plots, infectivity was similar at the three sampling dates, although propagule number increased with time. In fallow plots, infectivity and propagule number declined progressively. Inoculum level fluctuated with time in both treatments, mainly in the 10-15 cm layer, and was most stable in fallow plots at 5-10 cm. Infectivity increased with increase in propagule size and the larger propagules were more infective at l2�C rather than 20�C. There was no difference between the conduciveness of soils from each layer in fallow plots, but in grass plots conduciveness increased with depth. Infectivity and propagule number of the fungus at respective depths appeared to be related to organic matter, conduciveness and fertility of the soil.




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).



Sign in / Sign up

Export Citation Format

Share Document