DrSimon Archer

Research Interests:
Diversity of populations of plant pathogens is the theme for two current projects, one involving Phytophthora disease of cocoa in which Alex Appiah (in collaboration with CABI Egham) is examining a range of isolates of the two main species that are currently found on this host in Ghana. One of these, the more agressive, is currently spreading steadily through the main cocoa-growing areas and is of great concern. In the other project Ansar Ali is studying the range of cultural characteristics of isolates of Rhizoctonia found on rice in Bangladesh, as a prelude to molecular fingerprinting of the isolates and comparison of their relative pathogenicity.

Two linked projects on the mycotoxin patulin are currently in progress. Established work on the physiology of the main producer, Penicillium expansum, growing post-harvest on stored apple, is being supported by a new study examining field factors that might explain the relative preponderance of patulin 'outbreaks' on some farms compared with others. The Silwood Park orchard, an environment unsprayed for many years is being used to establish baseline ecological information on pathogen abundance and habitat.

Plant pathologists continue to make an input to the work of the environmental pollution group, Julie Beare finished her studies on the interactions between Melampsora and Marsonnina leaf diseases of poplar and the incidence of ozone pollution. Meanwhile, Nic Jarraud is examining a parallel system, that of tar spot of sycamore, but this time including aphid infestation in a four member interaction. Human interference seems to have influenced distribution of this disease in unpredictable ways and current gaseous pollutants are but one and probably not dominant factor.