Influence of the fungal hyperparasite Trichoderma harzianum on the growth of Epichloë typhina, an agent of choke disease in grasses

Abstract

In its sexual stage, the fungus Epichloë typhina (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 E. typhina. One potential solution is the use of hyperparasites as biocontrol agents, for example, the fungus Trichoderma harzianum, known for its ability to parasitize other parasites. We investigated the effects of T. harzianum on E. typhina (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) E. typhina 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 T. harzianum. The results indicate that the presence of T. harzianum has an inhibitory effect on the growth of mycelium in E. typhina. Therefore, this hyperparasite can be used to develop safe methods of limiting the spread of choke disease.