Scientific name: Xanthium strumarium
Afrikaans name: Kankerroos
English name: Cocklebur
Cocklebur is a branched, semi-herbaceous, annual plant, growing up to 1,5 m high, of which the seedlings are particularly poisonous.
Adult plants have deep, sturdy taproots and stems are reddish brown with red speckles which make them appear coarse. Leaves are simple, alternately arranged, egg-shaped (ovoid) to heart-shaped (cordiform) and sawed (serrate) margins.
Fruits are produced in distinctive axillary achenes, up to 2 cm long, brown, woody, crowned with two sturdy horns and covered with hooked spines that can easily cling to clothes and the coats of animals. Seeds are two per fruit, one larger than the other, blackish, ovally flattened, up to 1,5 cm long.
Cocklebur is a strong competitor. It is known for its strong competitive effect on annual crops. Seeds can be dormant in the soil for long periods due the size of the seeds and can germinate from deep burial depths. It reproduces via seed only, is a large-seeded, deep germinator and are widespread in southern Africa.
Shallow cultivation after emergence of seedlings can give effective control.
Although a number of pre-emergence herbicides are registered for control of cocklebur in maize and wheat, control is erratic. Post-emergence herbicides give more effective control. Effectivity of herbicides decreases as the plants grow bigger and time of application is therefore crucial. Strictly follow the specific instructions and dosages on the label of each product.
Always contact a reliable chemical advisor before using any chemicals to ensure the correct dosage and specifications on the label are adhered to.
TABLE 1: Herbicides registered for the control of cocklebur in maize.
|Time of Application
|Pre-emergence application within five to six days after planting
Post-emergence when crop is 30 cm tall, otherwise use drop arms for directed spray
|Post-emergence, when weeds are actively growing, five to six leaf stage
|Pre-emergence, with plant or within three days after planting
Early post-emergence application, not later than four
leaf stage of the weed
|Pre-emergence or early post-emergence
|Pre- or post-emergence application
|Pre-emergence or post-emergence, before four leaf stage of
|Post-emergence application, between four to six leaf stage of the weed
|Post-emergence, till crop is 30 cm tall
|Early post-emergence, before six leaf stage of the weed, use in tank mix with atrazine or atrazine/terbuthylazine
|Pre-emergence, use in tank mix with metolachlor or s-metolachlor
|Post-emergence, only on glyphosate-tolerant cultivars
|Pre-emergence, within five to six days after planting
Post-emergence, till crop is 30 cm tall
|Pre- or post-emergence
Use only in tank mixes with atrazine, atrazine/ terbuthylazine,or s-metolachlor
|Pre-emergence application, within three days after planting
Early post-emergence, in tank mixes with mesotrione
|Post-emergence, between four to six leaf stage of weed, in tank mix with 2,4-D or bromoxynil
|Early post-emergence application, before six leaf stage of the weed, in tank mix with atrazine or atrazine/terbuthylazine
TABLE 2: Herbicides registered for the control of cocklebur in wheat.
|Time of application
|Apply between growth stages seven to thirteen of the crop
|Post-emergence application, when weeds are actively growing, five to six leaf stage
|Apply on young, actively growing weeds
|Post-emergence application, when weed are between leaf stages four to six
|Only in tank mixes with Enhancer (10 g - 12 g) + Reaper (10 g) + adjuvant
|Apply between growth stages seven to 13 of the crop