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Communication Dans Un Congrès Année : 2011

Effect if wheat debris as source of primary inoculum on the early stages of Septoria leaf blotch epidemics

Résumé

Management strategies of Septoria leaf blotch could be improved by a better characterization of the onset and early stages of epidemics. The inoculum build-up and overseasoning potentially involve various fungal structures (ascospores, pycnidiospores, mycelium) and plant material (wheat seeds, stubble and debris; wheat volunteers; other grasses). Among the mechanisms reportedly involved in disease establishment and year-to-year disease transmission, infection by ascospores, wind-dispersed from either distant or local infected wheat debris, is considered as the most significant. Nevertheless, infection by pycnidiospores, splash-dispersed either from neighbouring wheat debris or from senescent basal leaves, has also been inferred from indirect evidence. The contribution of wheat debris to the early stages of Septoria leaf blotch epidemics and the relative importance of different types of inoculum to the establishment of Mycosphaerella graminicola were assessed in a three-year, field experiment conducted in the Paris Basin, a main wheat producing area in France. Three options of debris management (chopped debris, removed debris followed by tillage, tillage in absence of debris) were tested, which had a strong effect, although transient, on the early epidemic dynamic: the more debris present on the soil surface, the more severe initial disease was. The relative production of pycnidiospores and ascospores was measured on the chopped debris. Autumn conditions, characterized by moderate temperature with alternating wet and dry periods, were favorable for the production of ascospores and pycnidiospores, which concomitantly peaked in October-November; thus both types of spores can be involved as primary inoculum in North-West European conditions. During the winter period, the decrease in primary inoculum delayed disease progress; later on, disease progress resumed because of the input of inoculum from remote origin (ascospores). Management of wheat debris at the plot scale cannot be expected to decrease final disease severity and yield loss, although it can reduce the local amount of primary inoculum. Such a decrease, however, is likely to be obtained by limiting inoculum on a larger scale, considering that local inoculum sources in a given plot will also act as inoculum sources for distant plots.
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Dates et versions

hal-01000709 , version 1 (03-06-2020)

Identifiants

  • HAL Id : hal-01000709 , version 1
  • PRODINRA : 43401

Citer

Frederic F. Suffert, Nathalie N. Galet, Ivan I. Sache. Effect if wheat debris as source of primary inoculum on the early stages of Septoria leaf blotch epidemics. 8. International symposium on Mycosphaerella and Stagonospora diseases of cereals, Sep 2011, Mexico, Mexico. pp.80. ⟨hal-01000709⟩
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