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.

Description

Wireweed is a large prostrate plant, with a long, fibrous taproot and small blue-green leaves growing alternately on stems up to 1.2 m long. Its flowers are small and pinkish white.

Wireweed seedlings have spear-shaped, hairless cotyledons that grow up to 15mm long.

Control

Wireweed needs a period of low soil temperature to germinate, but its long taproot allows it to persist through hot, dry weather.

A second post-emergent herbicide spraying should help manage late emergence in winter crops, but a rotation to renovation crops and/or pastures may be required to clean up heavily infested paddocks.

Related Pests

Indian hedge mustard

Sisymbrium orientale

Indian hedge mustard is found in the cropping areas of Western Australia, northern and western New South Wales and southern Queensland. Its seeds are included in the ‘small foreign seeds’ fraction of allowable grain contaminants.

Turnip weed

Rapistrum rugosum

Turnip weed can compete particularly strongly with pulse crops, but will also substantially reduce wheat yields if it is not controlled. Better adapted to hot, dry conditions than most other brassica weeds, turnip weed is widespread in New South Wales and Queensland with the potential to become more common in all cropping areas.

Spiny emex - Doublegee

Emex australis

Doublegee is a very widespread weed that can grow on a range of soil types. In WA it is mainly found on red-brown soils with neutral to slightly alkaline pH. Just 8–9 doublegee plants/m2 can reduce wheat yield by up to 50%.