D. L. Chatel

Publication Date


Document Type


DAFWA Collections

Grains and field crops


(Feb 1976) This report covers the three major clover scorch activities for the year: A) The tolerance screening at Denmark. B) The dry matter production in the second year of a mowing trial, in which clovers with and without scorch were compared the previous year. C) A summary of the first four years of a disease incidence survey - and an examination of some meteorological factors in relation to disease development. The first two were done jointly with Dr C.M. Francis. The following tentative hypotheses are advanced to explain the regional differences in the distribution of clover scorch: a) The disease becomes established easily and develops seriously in those areas with mild winter temperatures and many rainy days, especially in spring; i.e, the south and southern coastal areas (note that most of the serious scorch in the Manjimup district is in the Northcliffe area - which is very close to the coast. b) The disease has not become serious in much of the Great Southern and other inland areas in which sub clover. grows well because of the colder winter temperatures - and the higher likelihood of extended dryer periods in spring. c) The disease is not a problem in the northern areas because of a combination of warmer temperatures and less rainy days - in winter and spring. d) Occasional outbreaks in areas such as Badgingarra, Bannister and Kojonup, which are far removed from the bad scorch areas, indicates that the organism is spread over most of the sub clover areas, It also suggests that occasionally temperature and moisture conditions are conducive to disease development - but their relatively short duration means that the disease does not get the opportunity to spread seriously. Climatic data needs to be fully examined in conjunction with aspects of disease infection, spread and spore survival before much more can be said about the distribution of the disease (in relation to location and time). 74D2

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Western Australia