The battle against herbicide resistance – tips on how to win it!

His dedication and skills have made Kobela Mokgohloa a successful cucumber farmer. Mokgohloa’s farm, Korema, in Winterveldt was the main feature in the sixth episode of African Farming, the agriculture television series on Mzansi Wethu (channel 163).

The energetic Angie Khumalo, host of the show, interviewed him and his family to find out why they are so successful.

For one thing, Mokgohloa uses hydroponics to grow his cucumbers. It is a method of growing crops by using mineral nutrient solutions in an aqueous solvent and without soil. In the case of Korema Farm, they use wood shavings and water.

Later during the episode, Khumalo and Freddie Ndindana, Corteva Technical Sales Representative, discussed in a studio interview the ever-increasing herbicide resistance found in ryegrass.

Ryegrass is a predominant grass weed species commonly found in small grain production areas of especially the Western Cape. It is highly variable and can easily cross-pollinate over some distance and rapidly develops herbicide resistance, as is the case at the moment. “This is why,” Ndindana said, “the increased ryegrass herbicide resistance is so interesting.”

It has a negative impact on the control options of ryegrass. Weed control is a labour-intensive, time-consuming practice and farmers use chemical compounds such as herbicides to combat the problem. However, this results in farmers becoming increasingly reliant on chemical weed control.

The downside of the continuous application of herbicides by the same method, is resistant mutations within the weed populations making the weed dominant, eventually rendering herbicide less effective.

Ndindana said adopting other control practices to strengthen sustainable crop protection will help in this regard, as farmers should move towards a more integrated weed control management plan that encompasses various methods, rather than relying on just one.

A balanced weed management strategy should include several tactics such as mechanical practices, crop rotation, cultural practices, and chemical practices, and should take into consideration various factors like soil and water management, natural enemies of the weeds and the use of competitive crops.

An effective weed control strategy must also be compatible with plans to manage other pests, as well as practices used to increase crop production, all within a quality environment.

For information: Call Corteva’s offices in Centurion, 012 683 5700 or in the Paarl, 021 860 3620.

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