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Weed control during winter

July 2016

Summer and winter weeds compete strongly with crops, therefore they have to be controlled to combat vigorous growth and the producing of seed in winter, as well as to prevent the surviving weeds from completing their life cycles and producing seed.

Growing weeds rapidly deplete the moisture and nutrients in the soil and during seasons when the rainfall is intermittent or scarce, it is even more critical to retain moisture for sustainable crop production in the next planting season.

The best time to spray weeds

The best time to spray weeds is late March or early April. This, however, makes the control of weeds in winter problematic as most of the summer crops are still on the fields when the weeds germinate. This complicates chemical weed control with ordinary tractor sprayers and it will most likely only be possible to use tractor sprayers post harvest when they can enter the fields.

Farmers must consider spraying for the conyza weed in late autumn, directly after harvest as this will facilitate the control of the weed in August and September.

According to weed science expert prof Charlie Reinhardt, at the University of Pretoria, it is just as important to control weeds on a headland, as it not only produces seed that can end up on the field, but can act as hosts for pests (insects) and pathogens.

Roundup® Turbo with glyphosate – controls grasses and herbaceous weeds

Roundup® Turbo is effective in the control of grasses and herbaceous weeds as the glyphosate is absorbed into the plant through its leaves and soft stalk tissue before being transported throughout the plant; even to the roots, nodules and bulbs. Glyphosate’s unique action in plants involves the inhibiting of a single enzyme only found in plants. Therefore, it is harmless to humans and animals.

As glyphosate is systemic, treated plants will slowly die over a few days or weeks. An advantage of glyphosate is that when it comes into contact with soil, it is rapidly inactivated as the chemical compound is adsorbed by soil microbes.

Effective weed control with herbicides starts by adhering meticulously to the recommendations on product labels.

Roundup Turbo® contains 450 g glyphosate/l. Roundup® Turbo is a registered trademark of Monsanto Technology LLC.

Always read the product label.

Article submitted by Magda du Toit, Corporate Communication Manager, Monsanto South Africa.
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Publication: July 2016

Section: Pula/Imvula