Four years of monitoring Mycosphaerella graminicola airborne inoculum and its relationship with disease symptoms in the field
(2013) 65th International Symposium on Crop Protection — Location: Ghent, Belgium (21.May.2013)
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- Abstract
- Mycosphaerella graminicola is the causal agent of Septoria tritici blotch (STB) in winter wheat. This disease is called a ‘gradient disease’ because it generally progresses from the lower to upper leaf stages. Airborne ascospores originating in stubble or trash are now considered to be the most important source of primary infection in autumn and winter, whereas the subsequent development of STB occurs through the infection of the upper leaves by splash-dispersed pycnidiospores produced on the lower leaves. Recent reports and observations, however, question the importance of ascospores in the progress of STB epidemics after stem elongation in wheat plants. A method based on real-time polymerase chain reaction (PCR) assay and using Burkard spore traps was developed to quantify M. graminicola airborne inoculum. The method was tested for its reliability and applied in a spore-trap network over a 4-year period in order to investigate the spatio-temporal distribution of airborne inoculum in Belgium. A seasonal distribution was observed, with the highest quantities trapped between June and mid-August and with clusters detected from September to April. Depending on the year or site, significant quantities of airborne inoculum were measured during the cereal stem elongation and heading stages, suggesting that ascospores contribute to the infection of upper leaves later in the season. When many peaks of airborne inoculum were detected during this period, the disease gradient due to the vertical progression of splash-dispersed pycnidiospores was not always well marked. The STB incidence observed on an upper leaf layer was sometimes greater than the incidence on a lower leaf layer, suggesting that the airborne inoculum accelerates the progression of the disease on the upper leaves of wheat plant. The exploration of the relationship between disease evolution, airborne inoculum detection and meteorological conditions would provide valuable information for integrated crop protection.
- Affiliations
Centre wallon de Recherches Agronomiques Plant Protection and Ecotoxicology Unit
Citations
Duvivier, M., Dedeurwaerder, G., De Proft, M., & Legrève, A. (2013). Four years of monitoring Mycosphaerella graminicola airborne inoculum and its relationship with disease symptoms in the field. 65th International Symposium on Crop Protection, Ghent, Belgium. https://hdl.handle.net/2078.5/46633