Capeweed

Arctotheca calendula

Capeweed is widespread throughout the southern cropping regions. Very little rain is needed to germinate capeweed seeds, so plants can emerge following ‘false breaks’ in early autumn and grow large before crops are sown.

Description

Capeweed plants are prostrate and can grow up to 50 cm in diameter. They form rosettes of succulent, hairy leaves with rounded ends.

The first two leaves grow as a pair. They are spear-shaped and may be scalloped. The remaining weeds grow singly.

Capeweed flowers are yellow with a black centre. Capeweed seeds are covered in pink-brown woolly hairs.

Control

Large capeweed plants can be very hard to control, so early herbicide application is important. That applies to knockdowns pre-sowing, but also makes Velocity – which can be applied as early as the 2-leaf crop stage – an advantageous post-emergent option.

Herbicides will be more effective when applied to healthy weeds that are actively growing. Stressed capeweed plants that have already survived early-season dry spells will be harder to control.

Related Pests

Wild radish

Raphanus raphanistrum

Wild radish is clearly now the most damaging broadleaf weed in Australian winter cropping. For many growers in the northern wheatbelt of Western Australia, herbicide-resistant wild radish is a threat to the viability of their cereal cropping rotation. While it is not yet such a threat in other areas, wild radish is a competitive weed wherever it emerges.

Annual ryegrass

Lolium rigidum

Annual ryegrass (Wimmera ryegrass) is arguably the most important grass weed competing with winter cereal crops in Australia. The rapid spread of herbicide-resistant populations in recent years has even threatened the viability of cropping in some areas.

Wireweed

Polygonum aviculare

The typical late germination of wireweed can make it hard to control. Although it may not compete strongly with the crop if it emerges when the crop is established, the long, tough branches of uncontrolled mature weeds can cause problems at harvest.