Relation of Inoculum Size and Concentration to Infection of Wheat Roots by<i>Gaeumannomyces graminis</i>var.<i>tritici</i>

Wilkinson, H. T.; Cook, Robert; Alldredge, J. Richard

doi:10.1094/phyto-75-98

Cited by 49 publications

(19 citation statements)

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“…From this study the likelihood of pathogenic inoculum surviving in root tissues appears to be high. The relative inoculum potential of pathogens within crowns as opposed to root tissues is unclear, In Ggt the threshold particle size below which disease symptoms do not appear varies in relation to the disease suppressiveness of a soil (Wilkinson et al 1985). The inoculum potential of different inoculum particle sizes will therefore be influenced Downloaded by [La Trobe University] at 10:37 13 June 2016 by the soil microflora in the different crop rhizospheres (Zogg 1976).…”

Section: Discussionmentioning

confidence: 99%

Survival of cereal root pathogens in the stubble and soil of cereal versus noncereal crops

Sturz

Bernier

1987

Canadian Journal of Plant Pathology

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Section: Discussionmentioning

confidence: 99%

Survival of cereal root pathogens in the stubble and soil of cereal versus noncereal crops

Sturz

Bernier

1987

Canadian Journal of Plant Pathology

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“…titici was derived from a single ascospore and stored at 4°C on one-fifth-strength potato dextrose agar (4 g of glucose, extract of 40 g of fresh potatoes, and 20 g of agar). The inoculum used to infest soil was prepared by growing the fungus on sterilized oat grains as previously described (50).…”

Section: Methodsmentioning

confidence: 99%

Contribution of phenazine antibiotic biosynthesis to the ecological competence of fluorescent pseudomonads in soil habitats

Mazzola

Cook

Thomashow

et al. 1992

Appl Environ Microbiol

345

147

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Phenazine antibiotics produced by Pseudomonas fluorescens 2-79 and Pseudomonas aureofaciens 30-84, previously shown to be the principal factors enabling these bacteria to suppress take-all of wheat caused by Gaeumannomyces graminis var. tritici, also contribute to the ecological competence of these strains in soil and in the rhizosphere of wheat. Strains 2-79 and 30-84, their TnS mutants defective in phenazine production (Phz-), or the mutant strains genetically restored for phenazine production (Phz+) were introduced into Thatuna silt loam (TSL) or TSL amended with G. graminis var. tritici. Soils were planted with three or five successive 20-day plant-harvest cycles of wheat. Population sizes of Phzderivatives declined more rapidly than did population sizes of the corresponding parental or restored Phz+ strains. Antibiotic biosynthesis was

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“…MacNish et al (1986) favoured the use of sand as inoculum because of the avoidance of artificially high levels of nutrients characteristic of colonized grain. Wilkinson, Cook & Alldredge (1985a) have shown that there is a threshold in size for both naturally and artificially colonized fragments of organic material, below which infection of roots was not recorded. It should be noted, however, that both G. graminis and R. solani are capable of extensive growth through soil in the absence of host roots.…”

Section: Discussionmentioning

confidence: 99%

Inoculum Efficiency and Pathozone Width for Two Host‐parasite Systems

Gilligan¹,

Simons²

1987

New Phytologist

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SUMMARYExperiments involving direct placement of inoculum at various distances from an infection court are used to estimate the probability of infection and/or disease of seminal roots of wheat by Gaeumannomyces graminis (Sacc.) Arx & Olivier var. tritici Walker and of germinating seeds of radish by Rhizoctonia solani Kuhn. Two concepts underlie the relationships under investigation. These are the pathozone, which is characterized by the furthest extent of inoculum from the host from which infection is recorded {z), and infection efficiency, which is characterized by two parameters a and /?. The asymptotic infection efficiency, /?, is estimated by the proportion of propagules that cause infection when placed in contact with the host; a is a measure of the decline in infection efficiency of propagules of inoculum with increasing distance from the host. Three non-linear models are used to describe the profile of infection efficiency over distance.The sensitivity of the method of placement of inoculum in detecting treatment effects is demonstrated first by showing differences in response amongst two isolates of G. graminis and two times of observation. Maximal values of z for G. graminis ranged from 4 to 8 mm, depending upon the type of inoculum of G. graminis and the growth medium used. Values of z for R. solani and germinating radish seeds varied from 12 to 16 mm for propagules comprising fragments of chopped potato soil inoculum sieved to 1 to 2 mm.The amounts and nutritional basis of inoculum infiuenced the probability of infection and the parameters a, y? and z. Thus, for G. graminis, estimated values for oT^, /? and z were greater for inoculum comprising colonized millet grains than for colonized sand particles. When seedlings of radish were exposed to clumps of propagules of R. solani, the parameters /? and z increased, while a decreased with increasing clumip density. Reduction in propagule size to 05 to 10 mm reduced the proportion of infected bosts. When clumps of seedlings of radish were challenged with clumps of inoculum of R. solani, the probability of infection of clumps increased with clump density, but there was no evidence for an effect on the probability of infection of individual seedlings within a clump. The relationship between the estimates of pathozone width and infection efficiency and models for infection of subterranean organs is discussed.

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Relation of Inoculum Size and Concentration to Infection of Wheat Roots byGaeumannomyces graminisvar.tritici

Cited by 49 publications

References 0 publications

Survival of cereal root pathogens in the stubble and soil of cereal versus noncereal crops

Survival of cereal root pathogens in the stubble and soil of cereal versus noncereal crops

Contribution of phenazine antibiotic biosynthesis to the ecological competence of fluorescent pseudomonads in soil habitats

Inoculum Efficiency and Pathozone Width for Two Host‐parasite Systems

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