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SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION
GENETICS
Dynamic of production and maturation of Gibberella
zeae perithecia on crop debris
V. Manstretta 1 , E. Gourdain 2 , V. Rossi 1
1 Instituto di Entomologia e Patologia vegetale, Università Cattolica del Sacro Cuore, via Emilia
Parmense 84, 29122 Piacenza, Italy; 2 Service Qualités-Valorisations, ARVALIS - Institut du végétal,
Station Expérimentale, 91720 Boigneville, France
E-mail: valentina.manstretta@unicatt.it
Gibberella zeae (anamorph Fusarium graminearum) is a key species of Fusarium
head blight and consequent mycotoxin accumulation in wheat grain. G. zeae
produces inoculum on residues of the previous crops. The dynamic of perithecia
production and maturation were studied in controlled conditions and in the field, to
acquire information on ascospore dynamics during the season.
Maize stalks inoculated with G. zeae were incubated at different temperatures (5
to 40°C) at 100% relative humidity (RH). Numbers and maturity class of perithecia
were assessed once a week over 8 weeks. Perithecia were produced between 10
and 30°C. At optimum temperatures (20, 25°C), perithecia emerged after 7 days
of incubation. Perithecia matured only at optimum temperatures, from 14 days of
incubation onwards.
Inoculated maize stalks were also incubated at 25°C between 62.5% and 100%
RH, which correspond to 15 to 80% moisture of the stalks. Perithecia were
produced at RH 75% and reached the maximum number at 100%. Perithecia
matured only with RH85%.
Studies were performed on different crops residues, inoculated and incubated at
20°C at 80% RH for 3 weeks. Perithecia were produced on all tested debris;
emergence started after 9 days on rape, sugar beet and potato, which had the
highest production, compared to wheat, maize, pea and sunflower.
Infested stalks were exposed outside between March and July over two years, in
three groups: i) always wet trough contact with a wet substrate, ii) kept dry by a
protection from rain, iii) left in natural conditions. Perithecia dynamics were
assessed twice a week. More perithecia and more rapid maturation occurred in
the wet residues, while no perithecia were produced in the dry one. More
perithecia were produced in the year with more rain.
In conclusion, temperature, moisture and kind of residue influence the dynamic of
perithecia production and maturation.
Keywords: Gibberella zeae, crop debris, temperature, moisture
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