Fusarium langsethiae (Torp and Nirenberg), investigation of alternative infection routes in oats

Fusarium langsethiae is a recently characterized fungus within the genus Fusarium. It is found as a grain contaminant of small grain cereals such as oats and barley, and to a lesser extent wheat. Fusarium langsethiae is particularly widespread in the Nordic countries and the UK where it poses a serious problem as the main producer of T-2 and HT-2 mycotoxins. The biology of F. langsethiae and its interaction with the plant remains poorly understood, partly hampered by difficulties reproducing a natural level of infection under controlled conditions. The reported study was designed as a series of glasshouse experiments to advance our understanding of F. langsethiae biology by investigating alternative infection routes and its proliferation in oats, Avena sativa. Various methods of seed, soil, and seedling inoculation, boot injection and spray inoculation, were tested. The results clearly show a strong preference of F. langsethiae for the panicle, ruling out alternative infection routes. At relatively low temperatures spray infection, accompanied by prolonged humidity, ensured a thorough establishment of the fungus both at flowering and at early dough stage. Boot injection proved to be a reliable working tool for production of an even and predictable grain infection. Apart from in the panicle, considerable fungal proliferation was only detected in flag leaf nodes, and was a direct consequence of the boot injection method. Fungal presence in the node tissue also correlated with significant stunting of infected shoots. In light of the results the pathogenic and endophytic abilities of F. langsethiae are discussed.