Influence of temperature on infection, growth, and mycotoxin production by Fusarium langsethiae and F. sporotrichioides in durum wheat

Information concerning the temperature requirements of the species causing Fusarium head blight of small grains is essential for understanding which species cause the disease in different areas and years, for developing weather-driven disease models and for predicting mycotoxin type and quantity in kernels. The optimal temperature range for growth was 20-25 \ub0C for Fusarium langsethiae and 25-30 \ub0C for F. sporotrichioides, and the optimum for production of both T-2 and HT-2 toxins was 15 \ub0C for F. langsethiae and 10-15 \ub0C for F. sporotrichioides. Floret infection occurred from 10 to 40 \ub0C for F. sporotrichioides (69.8% average incidence of infected florets) and from 10 to 35 \ub0C for F. langsethiae (17.6% of infected florets). The optimal temperature for spike colonisation was 25 \ub0C for F. langsethiae and 30 \ub0C for F. sporotrichioides, and the optimal temperature range for mycotoxin production was 15-35 \ub0C for F. langsethiae and 20-25 \ub0C for F. sporotrichioides. The quantity of fungal DNA in inoculated spikes was 5.5-times greater for F. sporotrichioides than for F. langsethiae; F. langsethiae DNA was first detected 2 days post-inoculation (dpi), and F. sporotrichioides DNA was first detected 4 dpi. Toxins were first detected 4 and 2 dpi for F. langsethiae and F. sporotrichioides, respectively