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Some Consequences of Cereal Monoculture on Gaeumannomyces graminis (Sacc.) Arx & Olivier and the Take‐all Disease 1
Author(s) -
Cunningham P. C.
Publication year - 1975
Publication title -
eppo bulletin
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.327
H-Index - 36
eISSN - 1365-2338
pISSN - 0250-8052
DOI - 10.1111/j.1365-2338.1975.tb02482.x
Subject(s) - biology , monoculture , take all , crop , pathogen , virulence , fungus , agronomy , pasture , host (biology) , botany , veterinary medicine , microbiology and biotechnology , ecology , biochemistry , gene , medicine
Studies were made of isolates of Gaeumannomyces graminis (Sacc.) Arx & Olivier var. tritici J. Walker from different length crop sequences of wheat and barley following permanent grassland. Studies were done on the influence of cropping intensity of soils, natural and steam disinfested, on disease expression from added inoculum. Efforts were also made to detect interactions between isolates and soils from the same and different cropping sequences. Investigation of variability in the pathogen related to virulence and specificity as well as to saprophytic traits. In general, mean virulence of isolates increased up to the point where approximately peak disease levels occurred in the field, and diminished subsequently. Host specificity of isolates from a monospecies system was also pronounced at this point whereas it was not evident in the first 2 crops; it did not increase further after the 5th or 6th cereal of a single species. There was evidence of loss of competitive saprophytic ability in isolates from long sequences as against those from 1st, 2nd and 3rd crops after permanent pasture. A differential sensitivity response from Gliomastix murorum (Cda.) Hughes var. felina (Marsh) Hughes was observed with isolates from 1 to a 3 year sequence compared with isolates from sequences of 4 to 8 years. Isolates from a 1st to a 3rd crop restricted colony growth of G. murorum in culture whereas those from 4th to the 8th cereal were overgrown by this fungus. Isolates from the 1st cereal after grass darkened considerably with age, those from a 2nd less so and those from a 3rd successive crop remained almost totally hyaline; those from longer sequences darkened considerably but were very variable for this trait. The influence of soil from more intensively cropped cereal sequences, which was destroyed by steam disinfestation, was to depress disease levels from applied inoculum. This soil inhibitory effect set in between the first and 3rd cereal.