This order of ascomycete fungi includes many species which are pathogens of trees, usually causing blue-stain, wilt or wood-rotting diseases. Several species cause serious diseases which have killed many trees, for example Dutch elm disease (caused by Ophiostoma ulmi and Ophiostoma novo-ulmi) or laurel wilt, caused by Raffaelea lauricola.
Typically the ophiostomatoids are transmitted by bark and ambrosia beetles. In the latter case the fungi are called "ambrosia" fungi and are used as food by the beetles. The order also includes saprobes and some are known as human pathogens. As fruiting bodies perithecia are formed. These have an opening through which the ascospores are discharged.
The following genera are currently entered under this order: