Abstract
A study has been made of various aspects of the biology of Erysiphe graminis DC., including its distribution and prevalence in Canada, method of overwintering, physiologic specialization, and the effects of various environmental factors on the development of different stages of the organism. The fungus causes the powdery mildew of cereals and certain grasses. It occurs in every province of Canada, but is more prevalent in British Columbia and the five eastern provinces. The evidence indicates that the fungus overwinters as mycelial mats on dead straw and as mycelial infections on overwintering hosts. Three new physiologic races of barley mildew have been identified, making a total of seven races isolated in Canada. In wheat mildew only Race 1 was isolated. A study of the stability of six races of barley mildew showed that they are distinct biologic entities comparable to physiologic races in cereal rusts. No evidence was obtained by cross inoculations that any variety of E. graminis, except possibly E. graminis Agropyri, can attack a non-suscept, or an immune variety of its host, or that injury of such hosts renders them susceptible. Conidia of E. graminis germinate on immune hosts and penetration proceeds as far as the papilla stage. Physiologic resistance manifests itself in some hosts by the death of the infected cells and in others by the distortion of the haustoria. The evidence indicates that the organism is homothallic. The cardinal temperatures for the germination of conidia are 0°, 10°, and 35 °C., while the best development of mildew occurs between 15° and 20 °C. Alternating temperatures induce perithecial development. Light is not an important factor, except indirectly, in the development of E. graminis. Alternate drying and wetting of perithecia is necessary to induce the formation of ascospores, but other stages are favoured by relatively dry conditions. Conidia germinate well even at zero humidity. Sprinkling infected seedlings with water checked the development of the disease. The addition to the soil of certain fertilizers and other chemicals commonly claimed to increase host resistance to powdery mildew did not increase the resistance of susceptible seedlings of wheat and barley.
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Claims 9
Claim · model-written summary
Three new physiological races of barley mildew were identified in Canada.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaree0 - Interactor
- mildewe0pathogen
- Outcome
- barley mildewe0
- Value
- Three new physiologic racese0
- Setting
- Canadae0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Three new physiologic races of barley mildew have been identified, making a total of seven races isolated in Canada.”
Claim · model-written summary
Only race 1 of wheat mildew was isolated.
- Taxon
- wheat
Triticum aestivume0 - Interactor
- mildewe0pathogen
- Outcome
- wheat mildewe0
- Value
- Race 1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In wheat mildew only Race 1 was isolated.”
Claim · model-written summary
Six barley mildew races were biologically distinct.
- Taxon
- barleyHordeum vulgaree0
- Interactor
- mildewe0pathogen
- Outcome
- distinct biologic entitiese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“six races of barley mildew showed that they are distinct biologic entities”
Claim · model-written summary
Cross inoculations found no attack on nonsusceptible or immune host varieties, with a possible exception.
- Interactor
- E. graminis
Blumeria graminise0pathogen - Outcome
- can attack a non-suscept, or an immune variety of its hoste0
- Qualifier
- except possibly E. graminis Agropyrie0
Not reportedTaxonDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No evidence was obtained by cross inoculations that any variety of E. graminis, except possibly E. graminis Agropyri, can attack a non-suscept, or an immune variety of its host”
Claim · model-written summary
E. graminis conidia germinate on immune hosts and penetrate to the papilla stage.
- Interactor
- E. graminisBlumeria graminise0pathogen
- Outcome
- germinate on immune hosts and penetration proceeds as far as the papilla stagee0
Not reportedTaxonDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Conidia of E. graminis germinate on immune hosts and penetration proceeds as far as the papilla stage.”
Claim · model-written summary
Some hosts resist through death of infected cells.
Not reportedTaxonDirection
Verbatim
e0“Physiologic resistance manifests itself in some hosts by the death of the infected cells”
Claim · model-written summary
Other hosts resist through distorted haustoria.
Not reportedTaxonDirection
Verbatim
e0“in others by the distortion of the haustoria”
Claim · model-written summary
Water sprinkling checked disease development in infected seedlings.
- Treatment
- Sprinkling infected seedlings with watere0
- Outcome
- development of the diseasee0
- Direction
- checkede0
Not reportedTaxonComparator
Verbatim
e0“Sprinkling infected seedlings with water checked the development of the disease.”
Claim · model-written summary
Fertilizers and chemicals did not raise powdery mildew resistance in susceptible wheat and barley seedlings.
- Taxon
- wheat and barleyHordeum vulgareTriticum aestivume0
- Treatment
- certain fertilizers and other chemicalse0
- Interactor
- powdery mildewe0pathogen
- Outcome
- resistance of susceptible seedlingse0
- Direction
- did not increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The addition to the soil of certain fertilizers and other chemicals commonly claimed to increase host resistance to powdery mildew did not increase the resistance of susceptible seedlings of wheat and barley.”
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fertilization · disease · Hordeum vulgare (barley)Positive and negative results
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See all 107 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.