Beschreibung:
<p>In its sexual stage, the fungus <italic>Epichloë typhina</italic> (Ascomycetes: Clavicipitaceae) is a pathogen that causes choke disease in many grass species. It forms stromata on developing inflorescences, resulting in reductions in flowering and seed production in the infected plants. As a result of fungal infection, economic losses in meadows and pastures have been reported. Unfortunately, there are no effective methods for reducing the spread of <italic>E. typhina</italic>. One potential solution is the use of hyperparasites as biocontrol agents, for example, the fungus <italic>Trichoderma harzianum</italic>, known for its ability to parasitize other parasites. We investigated the effects of <italic>T. harzianum</italic> on <italic>E. typhina</italic> (strain CBS 122147) in Petri dishes containing PDA medium using two methods: a dual-culture method and a precolonized plate method. Three strains of E. typhina of different origins were used. These experiments showed that: (1) <italic>E. typhina</italic> mycelium grew slower in the presence of T. harzianum and could be overgrown by hyperparasite mycelium, and (2) all strains of E. typhina responded similarly to <italic>T. harzianum</italic>. The results indicate that the presence of <italic>T. harzianum</italic> has an inhibitory effect on the growth of mycelium in <italic>E. typhina</italic>. Therefore, this hyperparasite can be used to develop safe methods of limiting the spread of choke disease.</p>