Xanthium spinosum

Due to the burrs adhering to wool, the risk of transferring seed to new areas can be reduced by shearing sheep before moving them from infected to clean pastures (Nursey, 1959). In Australia, X. spinosum is one of the most serious weeds spread by livestock, which carry burrs from one centre to another, so early recognition is essential for effective control (Gardner, 1942). Due to its toxicity and unpalatability, grazing is not a useful control method.
Physical/Mechanical Control
Control is possible by early mowing, cultivation or crop rotation, or by cutting and burning before the burrs ripen. As this annual weed spreads entirely by seed, it can be relatively easily controlled by cultivation on arable land, and on pastures. Eradication should aim to prevent seed development for at least three years (Orchard, 1949;Parsons, 1973). Single plants can be easily pulled out or hoed. If removal is done after flowering, it is important to burn the plants to ensure that the seeds are completely destroyed (Pitcher, 1989). Due to the long dormancy of the seeds, periodic repeated physical control will be required.
Chemical Control
The most common type of chemicals used to control X. spinosum are the broad-leaf selective herbicides. Young plants are easily killed by one application of 2,4-D or MCPA applied to healthy, growing, non-flowering plants, whereas older plants need more than one application (Meadley, 1956;Orchard, 1949). The most effective time for the application of 2,4-D is reported to be at the 3-5 leaf stage of growth, when it is able to better penetrate the waxy coat on the leaves (Pitcher, 1989), or before the flowering stage in February-March (Nursey, 1959). Imazaquin is also reported to be effective (Weber, 2003), and in irrigated soyabeans in New South Wales, Australia, imazaquin gave significantly more control of X. spinosum than bentazone, but did not control X. spinosum when applied after the formation of the 3 pronged spines (Andrews, 1993). However, Andrews (1993) considered that imazaquin provided the greater season-long control and was therefore the preferred herbicide.