Archivio Journal of Plant Pathology

Abstract:

The effect of temperature and humidity on the infection of wheat head tissues by four fungal species causing head blight (Fusarium avenaceum, F. graminearum, F. culmorum, Microdochium nivale) was studied by controlled- environment experiments. Detached spikes were inoculated at flowering with a spore suspension and incubated at different temperatures (10.0 to 35.0°C), wet and in a saturated atmosphere. Infection frequency of glumes after different incubation times (4 to 72 hours) was determined by re-isolation of the fungi that had been inoculated. Regression models were then elaborated and used to compare species and to define their cardinal temperatures for infection. F. avenaceum and F. graminearum showed the highest infection frequency, with optimum at 28.0-29.0°C; M. nivale and especially F. culmorum had a lower infection frequency, with optimum at 18.0°C and 26.5°C, respectively. Spikes were then inoculated at optimum temperature for each species, either in the presence or in the absence of a film of water, under different regimes of relative humidity (100% to 65%). Reduction of relative humidity during incubation increased the frequency of glumes infected by F. culmorum, whereas it created unfavourable conditions for the other species.