Control of weeds in maize and wheat – Part 9: Benghal wandering Jew

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    A Benghal wandering Jew seedling.
    Adult plant.

     

    Underground seed and inflorescence.
    Seed of Benghal wandering Jew.

     

    Scientific name: Commelina benghalensis
    Afrikaans names: Bengaalse wandelende Jood, Bengaalse-Commelina,wandelende Jood, blouselblommetjie
    English name: Benghal wandering Jew, Benghal Commelina, Wandering Jew

    Short description

    Benghal wandering Jew is a multi-branched, rather erect annual soft herb. It has thin roots and white underground runners (rhizomes) that also produce flowers and seeds. Stems are round, bright green, ribbed and hairy (hirtous). Although it has broad leaves, they have the typical parallel venation of monocotyledonous plants.

    Leaves are simple, alternately arranged, egg-shaped (ovoid). Flowers are axillary, small, ink-blue, nearly sessile and last for only a few hours.

    It has the ability to produce both aerial and subterranean flowers with seed. Fruits are capsules with three locules and contain one semi-orbicular seed in the dorsal locule and two compressed seeds in each of the other two locules.

    The aerial seed is small and the subterranean seed is rather big. They are grey to nearly black and the surface of the testa is rough. Reproduction occurs in various ways, namely by means of seeds, which occur above-ground (small), as well as underground (large), and also through cuttings.

    Distribution

    Widespread in southern Africa, but more common in summer rainfall regions. It is regarded as difficult to control.

    Because of difficult and insufficient control, this weed is rapidly increasing – especially where reduced tillage or no-tilling is practised. When occurring in dense stands, it becomes a strong competitor.  Later in the season it forms a thick “matt-growth” between crop rows, especially when crops are physiologically matured making control difficult.

    Control

    Cultivation
    Shallow hoeing with a harrow will only cut the plants in pieces and if the cuttings are not buried deeper than 50 mm, it will root and regrow. Cuttings will only die if they are buried deeper than 50 mm. Therefore shallow hoeing with a harrow will rather spread than control the weed.

    Chemical
    Chemical control is the best method of control for this weed. The small, subterranean seed emerges in shallow soil and pre-emergence herbicides usually gives the most effective control. The large subterranean seed can emerge as deep as 150 mm and pre-emergence herbicides gives precarious control. Therefore post-emergence herbicides gives better control of Benghal wandering Jew, while hormone type herbicides (2,4-D, dicamba and MCPA) are the most effective.

    Where wandering Jew is a serious problem, the best results will be obtained by a split application of a suitable grass herbicide pre-emergence, followed by a post-emergence application of a suitable broadleaved herbicide. Wandering Jew seedlings should preferably not be sprayed around four leave stadium and no later than six leave stadium.

    Several herbicides are registered for the control of wandering Jew in maize and wheat (Table 1 and Table 2). On most of the labels of the herbicides a note on the control of wandering Jew can be found and doses usually have to be increased for effective control.

    TABLE 1: Herbicides registered on maize for the control of wandering jew.

    Active ingredient Formula Time of application
    acetochlor


    700 g/litre

    840 g/litre

    900 g/litre

    960 g/litre
    Pre-emergence and early post-emergence of the crop


    acetochlor/atrazine/simazine


    160/165/165 g/litre

    Pre-emergence, with planting or just after planting


    acetochlor/atrazine/terbuthylazine125/187,5/87,5 g/litre

    150/225/225 g/litre

    178,6/160,7/160,7 g/litre

    250/225/225 g/litre

    350/175/175 g/litre

    Pre-emergence, with plant or within three days after planting. Early post-emergence, but not later than four leaf stage of the weed


    acetochlor/EPTC

    150/350 g/litrePre-emergence of weed and crop


    alachlor384 g/litre

    480 g/litre
    Pre-emergence, with planting or just after planting



    alachlor/atrazine336/144 g/litrePre-emergence, with planting or just after planting

    atrazine

    500 g/litre

    900 g/kg
    Pre-emergence, with planting or just after planting

    atrazine/bendioxide
    200/200 g/litre
    Post-emergence, between two to six leaf stage of the weed
    atrazine/cyanazine

    167/333 g/litre

    250/250 g/litre
    Pre-emergence and early post-emergence of the crop
    atrazine/mesotrione/s-metolachlor

    208,5/26,8/208,5 g/litrePre-emergence of the crop and weed
    atrazine/metazachlor/terbuthylazine

    210/60/210 g/litrePre-emergence or within three days after plant. Post-emergence as follow-up application
    atrazine/metolachlor

    300/300 g/litrePre-emergence or within three days after planting

    atrazine/metolachlor/terbuthylazine


    174/252/174 g/litre

    262,5/175/262,5 g/litre
    Pre-emergence and early post-emergence, but only where grasses have not emerged yet and broadleaf weeds are not bigger than four leaf stage

    atrazine/s-metolachlor


    370/290 g/litre

    Pre-emergence, within three days after planting

    atrazine/sulcotrione

    300/125 g/litre

    Pre- or post-emergence application

    atrazine/terbuthylazine

    250/250 g/litre

    270/270 g/litre

    300/300 g/litre

    450/450 g/kg
    Pre-emergence or early post-emergence, before broadleaf weeds have reached four leaf stage

    bendioxide

    480 g/litre

    Post-emergence, when weeds are actively growing

    bromoxynil

    225 g/litre

    450 g/litre

    Post-emergence, before weeds reach six leaf stage

    bromoxynil/terbuthylazine

    150/333 g/litre

    Post-emergence

    dicamba

    480 g/litre

    700 g/litre
    Post-emergence, till crop is 30 cm tall. Can also be mixed with atrazine

    dimethenamid-P

    720 g/litre

    Pre-emergence or within three days after planting

    dicamba/topramezone

    160/50 g/litre

    Early post-emergence before six leaf stage, use in tank mix with atrazine or atrazine/terbuthylazine and Dash HC

    glyphosate/mesotrione/s-metolachlor

    250/25/250 g/litre

    Post-emergence, only on glyphosate-tolerant cultivars

    mesotrione

    480 g/litre

    Pre- or post-emergence. Only use in tank mix with atrazine, atrazine/ terbuthylazine or s-metolachlor

    mesotrione/s-metolachlor

    83,3/416,7 g/litre

    Pre-emergence of weed and crop

    metolachlor

    800 g/litre

    840 g/litre

    915 g/litre

    950 g/litre
    Pre-emergence or within three days after planting

    metribuzin

    480 g/litre

    Post-emergence, between four to six leaf stage of the weed, when weeds are actively growing

    s-metolachlor

    915 g/litre

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

    s-metolachlor/terbuthylazine

    312,5/187,5 g/litre

    Early post-emergence, in tank mix with mesotrione

    tembotrione

    420 g/litre

    Early post-emergence, use in tank mix with Atrazine 500 SC, ammonium sulphate and Ballista

    terbuthylazine

    600 g/kg

    Pre- and early post-emergence, till four leaf stage

    TABLE 2: Herbicides registered on wheat for the control of benghal wandering jew.

    Active ingredient Formula Time of application
    2,4-D




    480 g/litre

    500 g/litre

    720 g/litre


    Apply between growth stages seven to 13 of the crop




    2,4-D/dicamba




    240/80 g/litre



    Apply between growth stages seven to 13 of the crop






    bendioxide



    480 g/litre



    Apply to young, actively growing weeds




    bromoxynil





    225 g/litre

    450 g/litre


    Early post-emergence, before six leaf stage of the weed





    dicamba



    700 g/kg

    Use only in tank mix with Enhancer (10 g tot 12 g) and Reaper (10 g) and a wetter (adjuvant)





    MCPA400 g/litre

    700 g/kg
    Apply between growth stages seven to 13 of the crop

    Therefore the specifications and doses for control of the wandering Jew have to be adhered to.

    Always contact a reliable advisor before using any chemicals to ensure the correct dose on the label is adhered to.
    Contact the writers at elbe.hugo@syngenta.com (Elbe Hugo) and, deweth@arc.agric.za (Hestia Nienaber).