Facts:
This seminar was organized by CBC - Centre for biological control at SLU and SP (the Technical Research Institute of Sweden) as part of the CBC's seminars series on biological control.
SLU news
Biological control of creeping thistle - an invasive species in New Zealand
Published: 15 June 2016
CBC and the SP jointly organized the seminar "Cirsium arvense - economic impact and potential of biological control of an European plant in New Zealand" held by Dr. Graeme Bourdot from the research institute AgResearch in New Zealand.
A thorny problem that cannot be fought chemically
The creeping thistle is not indigenous to New Zealand, but has been introduced by humans. The thistle is a major problem in pastures and can lead to major economic losses. To combat the weed with chemical pesticides also kills clover plants, which is important for nitrogen fixation and thus the nitrogen supply to the pastures. Therefore, there is a great need for alternative control methods in the fight against creeping thistle.
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Dr. Graeme Bourdot from AgResearch talks about how fungi can be used as biological control agents against the creeping thistle. Photo: Hanna Friberg.
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Fungi can attack injured and humid thistles
Experiment with scything the pastures when it is raining has had a good effect. The effect is probably due to the fact that harmful fungi can attack thistles easier when the thistles are damaged and the humidity is high. This is a type of conservation biological control that is currently used by many farmers.
Another method that has been tried is to add various fungi, including Sclerotinia sclerotiorum. S. sclerotiorum is a harmful fungus that can attack many different plants. Another fungi that has been tested is the thistle specific rust fungus Puccinia punctiformis. S. sclerotiorum has given a decline of the creeping thistle with 65%, but unfortunately it cannot be stored very well.
Thistle Beetles - another promising method
A third attempt to combat thistles with biological methods has been made with a small European thistle beetle that is good at eating thistle leaves. So far, all these biological control methods arenat the research stage, but Dr. Graeme Bourdot has high hopes that a biological control strategy will come into general use in New Zealand in the near future.
- This was a very interesting seminar! The use of biological control against weeds on a large scale is still far rarer than biological control of pests and plant diseases. It could provide substantial environmental and economic benefits worldwide, says Margaret Hökeberg, director of the CBC.
Contact
Margareta.Hokeberg@slu.se, 018-671863, 0703-452802