Annual ryegrass toxicity
Encyclopedia
Annual ryegrass toxicity (ARGT) is the poisoning of livestock from toxin contained in bacterially-infected annual ryegrass
. The toxin is produced by the bacterium Rathayibacter toxicus (formerly Clavibacter toxicus), which is carried into the ryegrass by the nematode
Anguina funesta
.
ARGT was first recorded in vicinity of Black Springs, South Australia, in the 1950s and then near Gnowangerup, Western Australia
, in the 1960s. The disease has spread rapidly and approximately 40,000 to 60,000 square kilometres of farmland in Western Australia and similar areas in South Australia are now infested by the ARGT-causing organisms. Most ARGT-related livestock losses occur during October to January, but losses have been recorded as late as April.
Herbicide applications aimed to reduce ryegrass population have been successful in reducing the risk of ARGT but have undesirable effects such as rapid reduction in pasture productivity and increase in ryegrass herbicide resistance.
A recently released biological control
agent, the twist fungus
, has been demonstrated to be effective in reducing the risk ARGT without the need of controlling ryegrass. The first use of the twist fungus inoculum was in 1997.
Ryegrass
Ryegrass is a genus of nine species of tufted grasses in the Pooideae subfamily of the Poaceae family. Also called tares , these plants are native to Europe, Asia and northern Africa, but are...
. The toxin is produced by the bacterium Rathayibacter toxicus (formerly Clavibacter toxicus), which is carried into the ryegrass by the nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
Anguina funesta
Anguina funesta
Anguina funesta is a plant pathogenic nematode....
.
ARGT was first recorded in vicinity of Black Springs, South Australia, in the 1950s and then near Gnowangerup, Western Australia
Gnowangerup, Western Australia
Gnowangerup is a town located south east of Katanning in the Great Southern region of Western Australia. The townsite was first gazetted in 1908 under the spelling of Ngowangerupp. Local dissatisfaction with this spelling led to it being altered to Gnowangerup in 1913.A branch railway from...
, in the 1960s. The disease has spread rapidly and approximately 40,000 to 60,000 square kilometres of farmland in Western Australia and similar areas in South Australia are now infested by the ARGT-causing organisms. Most ARGT-related livestock losses occur during October to January, but losses have been recorded as late as April.
Herbicide applications aimed to reduce ryegrass population have been successful in reducing the risk of ARGT but have undesirable effects such as rapid reduction in pasture productivity and increase in ryegrass herbicide resistance.
A recently released biological control
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
agent, the twist fungus
Twist fungus
Twist fungus is a fungus found in southern Australia, the Middle East and Europe. Recent research by scientists from Western Australia has found the fungus is capable of controlling organisms that cause the disease of livestock known as annual ryegrass toxicity. An inoculum of the fungus was...
, has been demonstrated to be effective in reducing the risk ARGT without the need of controlling ryegrass. The first use of the twist fungus inoculum was in 1997.