23 January 2012

2 minute read

Oceania

Department veterinary officer Trudy Clarke said there have been reports of new cases of sick livestock where hyssop loosestrife (Lythrum hyssopifolia), also known as lesser loosestrife, is considered to be the likely cause of illness.

“Producers should look for the weed in low-lying areas, around and behind dams, in contours, gullies or any wet areas on their property,” Dr Clarke said.

“Stock losses have only been associated with green hyssop loosestrife, therefore killing the weed is recommended.”

The department’s senior research officer in Integrated Weed Management John Moore said herbicides registered in Australia for control of young Hyssop loosestrife included diflufenican (e.g. Brodal®), diflufenican + MCPA (e.g. Tigrex®), and mixtures of terbutryn + triasulfuron.

“Mature hyssop loosestrife is expected to tolerate normal rates of many common herbicides,” Mr Moore said.

“Glyphosate plus triclopyr appears to provide the most cost effective control on similar plants overseas.

“However, these can make plants more palatable and therefore increase the risk of poisoning while the plant is dying.

“Desiccant herbicides such as paraquat are expected to be more effective than slashing where grazing of the paddock is required.”

Mr Moore said during summer, apply post emergence sprays very early morning when the plants are least stressed or preferably a day or two after rain.

When choosing to spray any weed, it is important that producers adhere to the grazing withholding periods of the products used and consider the longer term implications of the chemical choice and its impact on the future use of the paddock.

After the plant is dead, producers should still graze the paddock with caution, monitoring stock for any signs of poisoning. Any producers experiencing stock losses are encouraged to contact their local DAFWA office or private veterinarian to obtain an accurate diagnosis and advice.

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