Control of weeds in maize and wheat – Part 12: Cocklebur

    2205

     

    Cocklebur at two leaf stage. Photo: John MacIntyre, Villa Crop.
    Young seedlings. Photo: John MacIntyre, Villa Crop Protection.

     

    Axillary achenes. Photo: Suzette Bezuidenhout Insert: Achenes with oval seed.
    Adult cocklebur plant in maize. Photo: Suzette Bezuidenhout.

     

    Scientific name: Xanthium strumarium
    Afrikaans name: Kankerroos
    English name: Cocklebur

    Short description

    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.

    Distribution

    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.

    Control

    Cultivation
    Shallow cultivation after emergence of seedlings can give effective control.

    Chemical
    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.

    Active IngredientFormulaTime of Application
    2,4-D

    480 g/litre

    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
    2,4-D/dicamba

    240/80 g/litre

    Post-emergence, when weeds are actively growing, five to six leaf stage
    acetochlor/atrazine/terbuthylazine

    125/187/187 g/litre

    150/225/225 g/litre

    200/150/150 g/litre

    250/225/225 g/litre

    250/250/225 g/litre

    350/175/175 g/litre
    Pre-emergence, with plant or within three days after planting

    Early post-emergence application, not later than four
    leaf stage of the weed
    atrazine/cyanazine

    167/333 g/litre

    250/250 g/litre
    Pre-emergence or early post-emergence
    atrazine/mesotrione/s-metolachlor


    208,5/26,8/208,5 g/litre
    Pre-emergence application
    atrazine/sulcotrione

    300/125 g/litrePre- or post-emergence application
    atrazine/terbuthylazine

    250/250 g/litre

    300/125 g/litre

    300/300 g/litre

    450/450 g/kg
    Pre-emergence or post-emergence, before four leaf stage of
    the weed
    bendioxide480 g/litrePost-emergence application
    bromoxynil225 g/litre.

    400 g/litre

    450 g/litre

    500 g/litre
    Post-emergence application, between four to six leaf stage of the weed
    bromoxynil/terbuthylazine

    150/333 g/litrePost-emergence application

    dicamba

    480 g/litre

    700 g/kg
    Post-emergence, till crop is 30 cm tall

    dicamba/topramezone

    160/50 g/litreEarly post-emergence, before six leaf stage of the weed, use in tank mix with atrazine or atrazine/terbuthylazine

    flumetsulam

    800 g/kgPre-emergence, use in tank mix with metolachlor or s-metolachlor

    glyphosate/mesotrione/s-metolachlor

    250/25/250 g/litrePost-emergence, only on glyphosate-tolerant cultivars

    halosulfuron750 g/kgPost-emergence application

    MCPA

    400 g/litre

    700 g/kg
    Pre-emergence, within five to six days after planting

    Post-emergence, till crop is 30 cm tall
    mesotrione

    480 g/litrePre- or post-emergence

    Use only in tank mixes with atrazine, atrazine/ terbuthylazine,or s-metolachlor
    mesotrione/s-metolachlor

    83,3/416,7 g/litrePre-emergence application

    s-metolachlor

    915 g/litre

    960 g/litre
    Pre-emergence application, within three days after planting

    s-metolachlor/terbuthylazine

    102,8/497,2 g/litre

    312,5/187,5 g/litre
    Pre-emergence application

    Early post-emergence, in tank mixes with mesotrione
    metribuzin

    480 g/litre

    Post-emergence, between four to six leaf stage of weed, in tank mix with 2,4-D or bromoxynil

    topramezone

    336 g/litre

    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.

    Active ingredient Formula Time of application
    2,4-D

    480 g/litre

    500 g/litre
    Apply between growth stages seven to thirteen of the crop

    2,4-D/dicamba

    240/80 g/litre

    Post-emergence application, when weeds are actively growing, five to six leaf stage

    bendioxide480 g/litre

    Apply on young, actively growing weeds

    bromoxynil

    225 g/litre

    255 g/litre

    400 g/litre

    450 g/litre

    500 g/litre
    Post-emergence application, when weed are between leaf stages four to six

    dicamba

    700 g/kgOnly in tank mixes with Enhancer (10 g - 12 g) + Reaper (10 g) + adjuvant


    halosulfuron750 g/kg

    Post-emergence

    MCPA

    400 g/litre

    700 g/kg

    Apply between growth stages seven to 13 of the crop

    Contact the writers at elbe.hugo@syngenta.com (Elbe Hugo) and deweth@arc.agric.za (Hestia Nienaber).