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Weed of the Week: Giant Fleabane

Giant Fleabane

Giant Fleabane

After the Deb, Monique and Jen came across this skyscraper Fleabane we had to acknowledge it as our weed of the week!

So what it is and where does it come from? Lets see what the NSW Department of Agriculture says about it…

There are three main species of fleabane in Australia:

1) C. bonariensis (flaxleaf fleabane)
2) C. canadensis (Canadian fleabane)
3) C. sumatrensis (tall fleabane). Of the three species, flaxleaf fleabane is the most common across Australia.

– Flaxleaf fleabane can grow up to 1 m tall and has deeply indented leaves. Its branches often grow taller than the main plant axis

– Tall fleabane can grow up to 2 m tall. Its leaves are less indented than flaxleaf fleabane and its branches do not grow taller than the main plant axis

– Fleabane is a prolific seed producer, each plant producing up to 110,000 seeds! and of these, up to 80% can be viable. The seeds do not possess dormancy so they can germinate whenever temperature and moisture requirements are met. Prevention of seed-set is vital for control

– Inconsistent control is often obtained with herbicide treatments, especially once plants exceed a diameter of 30 mm

– Often fleabane germinates under a winter crop after the normal application time for post-emergent herbicides. The plants develop unobserved until harvest, when they begin to elongate for flowering. The harvest machinery cuts the tops off the plants but they survive in the summer fallow as woody deep-rooted plants with little leaf area to absorb herbicides. It is uneconomical to control these surviving plants with herbicides. However, if left unchecked, they continue to produce seed through the summer.

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