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SESSION 5: DISEASE CONTROL AND FORECASTING MODELS
P124 - Saprophytic survival of Fusarium graminearum
in crop residues
J. Leplat 1 , L. Falchetto 2 , P. Mangin 2 , C. Heraud 1 , E. Gautheron 1 , N.
Gautheron 1 , V. Edel-Hermann 1 , C. Steinberg 1
1 INRA, UMR1347 Agroécologie 17 rue Sully, BP 86510, F-21000 Dijon, France; 2 INRA, UE Domaine
d’Epoisses, F-21110 Bretenières, France
Email: christian.steinberg@dijon.inra.fr
Fusarium Head Blight (FHB) is one of the most important disease altering wheat
crops. A field experiment was conducted to better understand the saprotrophic
development of Fusarium graminearum and its consequences on FHB, to
characterize the relative importance of the different sources of FHB inoculum and
the accumulation of mycotoxins in grains and subsequently, to determine early
indicators of future disease development on ears and accumulation of mycotoxins
in grains. The development of F. graminearum in the soil and crop residues was
monitored in controlled conditions.
The inoculum hosted by seeds and/or buried with crop residues in the topsoil had
only an effect on the winter development of the disease. In contrast, the main
source of inoculum causing FHB disease on ears and accumulation of mycotoxins
in wheat kernels came from residues left on the soil surface. Monitoring of plant
development from sowing to harvest, crop management and soil and weather
conditions produced a large database. Unfortunately, the role of climate was
decisive in the development of the Fusarium-host plant interaction, thus prevented
the use of early indicators to accurately predict the risks of yield losses and
accumulation of mycotoxins involved.
F. graminearum was regulated by the soil microflora. However, crop residues
provide the fungus spatial and trophic niches favourable to its development. The
exploitation of these niches by F. graminearum depends on the nature (previous
crop and C/N) of the residues. Maize stubbles provide a greater carrying capacity
than wheat straw and rapeseed residues while mustard has a suppressive effect
for the fungus.
The management of crop residues is a key point to control the development of
FHB. A strong emphasis should be placed on the biological decomposition of crop
residues at the soil surface or/and on the use of suppressive intermediate crops
such as mustard to limit the soil inoculum potential of saprotrophic F.
graminearum.
Keywords: early indicators, ecological niche, epidemiology, conservatoire
biological control
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