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FARM SERVICES | 3 September 2009

Management the key to Fleabane Control

Year round vigilance, constant monitoring of paddocks and top quality herbicide application are the keys to controlling flaxleaf fleabane, according to a Landmark research team on the Darling Downs.


There is general industry agreement that no-till farming has encouraged the spread of this notoriously hard to control weed in recent years.


For the last few years it has topped many farmers’ lists of weeds of concern across southern Queensland and northern New South Wales.


However, according to Pittsworth Landmark agronomist Hugh Reardon-Smith, flaxleaf fleabane research is making progress, with agronomists, and the growers they advise,  “starting to get a handle on how to control it”.


He says research by Landmark agronomists points to management being the key to control of fleabane, because there is no one specific way of doing so.


“We tell growers the first step in any strategy against flaxleaf fleabane is close monitoring of weed flushes to ensure timely herbicide application and maximum herbicide performance,” Hugh says.


“It’s all about management. For instance, glyphosate and 2,4-D can control fleabane effectively, as long as the weed seedlings are still at the two to three leaf stage.


“However, stress is a major factor in the success of any control. In dry conditions and heatwaves a grower could be looking at what seems to be small fleabane plant.


“But that’s only above the surface of the soil. A stressed plant can have a big root system and you have to be sure you kill every bit of it.”


Hugh says flaxleaf fleabane must be actively growing for control to be successful, and once the weed is established this means spraying within seven days of 50mm of rain.


For established plants, active growth is vital for successful control.


He says flaxleaf fleabane has a number of attributes, which make harder to control than most other weeds. These include:


  • being a prolific seeder, producing as many as 100,000 seeds per plant;
  • seedlings can an emerge any time from late autumn to spring and early summer, whenever temperatures are between 10 and 25 degrees, and
  • it is relatively tolerant of herbicides, at least in part due to its hairy characteristics.


The Landmark Product Development team evaluated a range of herbicide options against fleabane.


They found some products, to be valuable at times but, for established plants, a double knock application is critical.


A “double knock” with Spray.Seed or one of the paraquats, applied five to seven days after an initial glyphosate treatment would be critical for success.


Residual herbicides can reduce fleabane emergence, as long as the soil surface is moist enough to activate them. Results then depend on the season.


“Even cultivation can be useful when the weeds are getting out of control and good conditions are not expected in the short term,” Hugh says.


“To achieve successful control, a large number of factors must be working in your favour.


“It’s a tall order to line everything up successfully, but it gives growers the best chance.”

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