Distribution of the airborne inoculum of wheat leaf rust and septoria tritici blotch : impact on epidemics in wheat fields and implications for integrated pest management
(2015)
Files
Duvivier-thèse-version-finale-2.pdf
Open Access - Adobe PDF
- 3.44 MB
Details
- Authors
- Supervisors
- Abstract
- Like pollen, spores of pathogenic fungi can take to the air in order to disperse. We have hypothesized that a quantitative analysis of the airborne inoculum of wheat pathogens would lead, first, to a better understanding of the epidemiology of wheat diseases and, second, to an improvement in short-term predictions, as a guide to farmers. Two major foliar diseases of wheat in Belgium were chosen: septoria tritici blotch (STB) and wheat leaf rust (WLR), which differ in propagation, development and survival mechanisms. STB occurs early in the wheat development, mainly through airborne contamination by ascospores, produced by the sexual cycle. Its spread to the upper leaves during wheat development is known to be mainly due to asexual pycnidiospores dispersed by rain splashes. However, airborne inoculum analysis indicated that STB inoculum was present throughout the growing season, with a seasonal pattern. Using mechanistic models, the study showed that contamination of the upper leaves could be better explained by taking account of the airborne inoculum, particularly when asexual reproduction was impeded (e.g., resistant varieties or early fungicide treatments). The detection profiles for WLR, a biotrophic pathogen, indicated the possible existence of a ‘green bridge’, whereby WLR overwinters on the seedlings and volunteers (self-sown) of wheat. It was also shown that the pathogen’s survival from one cropping season to the next one was highly dependent on weather conditions in autumn and winter. Airborne WLR inoculum, however, can be a limiting factor in the development of severe epidemics. The prediction of WLR infection of upper leaves was improved by analyzing the airborne inoculum data or the predicted concentrations at critical points in time. The inclusion of airborne inoculum profiles, as well as weather conditions, in the monitoring of STB and WLR development in the field led to a review of the conditions needed for the upper leaves of wheat to be infected by these two important pathogens. Taking account of airborne inoculum data emerged as an important factor in the choice of fungicide treatments and the application of integrated pest management strategies, which would potentially have important economic and environmental benefits.
- Affiliations
Citations
Duvivier, M. (2015). Distribution of the airborne inoculum of wheat leaf rust and septoria tritici blotch : impact on epidemics in wheat fields and implications for integrated pest management. https://hdl.handle.net/2078.5/187571