Since 1974, SA has released more biocontrol agents on water hyacinth than any other country.
Manual control of water hyacinth (Eichhornia crassipes), a perennial aquatic plant native to the Amazon Basin of South America, is widely used, but it is labour intensive and expensive.
Herbicides have been employed since the late 1970s but are costly, and may have unwanted non-target effects.
The first biocontrol agent was released in 1974. Since then, South Africa has released more agents on water hyacinth than any other country. Established biocontrol agents include:
• Water hyacinth grasshopper (Cornops aquaticum)
One of the most damaging insects on water hyacinth, C. aquaticum, promises to have a significant impact on the density and expansion of infestations in South Africa.
Adult grasshoppers are 23mm to 29mm long (females are slightly larger), green, with a black stripe extending from eye to wing tip on each side of the body.
Nymphs are mottled blue-brown/red.
Both nymphs and adults are highly mobile and can swim; adults are strong fliers, capable of dispersing to other water hyacinth infestations.
The grasshopper has a voracious appetite, and is capable of consuming large amounts of plant tissue. The subsequent loss of photosynthetic area severely hampers plant growth and slows vegetative reproduction.
Denne historien er fra Farmer's Weekly 7 September 2018-utgaven av Farmer's Weekly.
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Denne historien er fra Farmer's Weekly 7 September 2018-utgaven av Farmer's Weekly.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
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