Fungi are important biological control agents. Within CBC we do research on fungi using both conservation biological control approaches and application biological control approaches. In both cases we are interested in how the use of biological control fungi can be optimised.
All soils have some potential for disease suppression. The biological and chemical properties of a soil determine how plant pathogenic fungi can establish and cause disease. There are several examples of so called disease suppressive soils, where a specific plant disease fails to develop despite the presence of a virulent inoculum and environmental conditions favourable for disease development. In some cases, the suppressiveness is long-standing and associated to a specific soil whereas in other cases, it can be induced e.g. by the cultural practices used. Many competition sensitive pathogens are suppressed by a high biological activity in the soil, which can be stimulated through addition of fresh or composted organic material, which in turn results in increased levels of organic material in the soil.
Here, we investigate how harmful fungi establish themselves on winter wheat and how a healthy microflora an reduce attacks. Photo: Hanna Friberg.
Other pathogens are suppressed by specific antagonists, for example hyperparasites – fungi parasitizing the pathogenic fungus. One important factor that influences the fungal community structure in agricultural soils is the cropping sequence. At CBC, we are interested in how fungi are influenced by the cultural management, and how specific fungal species and fungal communities that suppress diseases can be stimulated through the design of the cropping system.
The importance of naturally occurring antagonists to fungal plant pathogens have so far mainly been studied in soil systems, but the same types of interactions are important also on above- ground plant parts. Within CBC, we are studying which factors that influence the community structure of the phyllosphere microflora, and its importance for plant disease development.
Fungi that are especially efficient in controlling plant diseases or insect pests can be added to the system through application of a biological control product. There are today several products on the market, and much research aiming at developing more products and at using their full potential. Metarhizium is an entomopathogenic fungal genus that is already used within biological control, e.g. to control locusts in Africa. At CBC, we are studying the occurrence and distribution of Metarhizium species in Sweden, and their potential to control insects.
A locust attacked by a fungus of the genus Metarhizium. Some Metharzium species areused to control insect pests in Africa. Photo: Wikipedia.
At CBC, we are also studying how biological control fungi that are used against root diseases are establishing in soils of different quality, and what we can do to enhance their establishment and thereby the efficacy. In some situations, introduced fungi can have difficulties to establish in certain soils. We want to know why, and if this problem can be overcome by combining the application of the fungi and the addition of plant material. This is one example of how CBC is studying how the use of biological control agents can be combined with other control measures for a more reliable control of pests and diseases.
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