Fleabane

Fleabane is the common name for several closely related annual weeds in Australia, mainly flaxleaf fleabane (Conyza bonariensis) and other Conyza species. They start as a low rosette of narrow, hairy, grey-green leaves before sending up a single upright stem that can reach 1-1.5 metres. Stem leaves are narrow and lance-shaped, arranged alternately, and covered in fine hairs that give the plant a slightly rough, dusty appearance.

Once mature, the plant branches near the top and produces hundreds of small, cream to pale yellow flower heads, each only a few millimetres across. These quickly turn into fluffy white seed heads similar to a small dandelion. A single plant can produce tens of thousands of tiny wind-dispersed seeds, which is the main reason fleabane spreads so readily along roadsides, into paddocks, garden beds, and neglected turf areas.

Fleabane germinates mainly in autumn and spring in most parts of Australia, though germination can occur almost year-round in warmer regions given enough moisture. Seedlings establish quickly in disturbed or bare soil, gravel, along fence lines, in garden beds, and in thin or patchy lawns where there is little competition from desirable plants.

Management relies heavily on catching the weed early. Seedlings and young rosettes (generally before the 9-leaf stage) are far easier to control than mature plants, which develop a tough, woody stem and a taproot that makes them noticeably more resistant to control. Improving lawn or garden bed density, mulching bare soil, hand removal of young plants before they set seed, and monitoring disturbed ground regularly all help reduce establishment. Because fleabane populations in parts of Australia have developed resistance to some commonly used control methods, rotating approaches and never letting plants reach flowering and seed-set is important for long-term management.