WeedSAT spot spraying heads to South Africa by April 2027

Spot-spraying technology that generates weed prescription maps from satellites with 30cm-by-30cm ground resolution is targeting commercialisation in South Africa before the winter rainfall planting season in April/May 2027. That is one prong of a broader shift, says Louise Bestbier, agricultural scientist at Stellenbosch University's Department of Agronomy: farmers must attack weeds at several life-cycle stages rather than lean on herbicides alone.

"You can't just eat less and expect everything else to fall into place. You also need to eat properly, exercise, get enough sleep and stay hydrated. Weed management works in much the same way – you need a holistic approach," Bestbier says.

Why does conservation farming raise the stakes?

Under conventional systems, ploughing uproots weeds and buries some seed deep enough to delay emergence. Conservation agriculture deliberately removes that disturbance to protect soil structure, conserve moisture and keep residues on the surface — and hands the weed-control job to chemistry. Repeated herbicide reliance builds selection pressure for resistance, particularly in ryegrass. Bestbier's answer: strategic cultivation, grazing, crop competition, cover crops and seedbank management used alongside spraying.

What did the windrow-burning trials find?

Stellenbosch MSc student Kaylen van Wyk tested chaff tramlining and narrow windrow burning over two seasons at Langgewens Research Farm near Moorreesburg in the Swartland. Both treatments showed visible differences in weed populations against the control, though not yet statistically significant — trials ran in areas of very high weed seed pressure, so the aim is to grind down the seedbank over several years.

A chute fitted behind the harvester concentrates chaff into a strip roughly 500mm to 600mm wide. Narrow windrow burning then destroys the trapped seed. Van Wyk recorded temperatures above 400°C in the windrows — enough to kill ryegrass seed. The windrows covered less than 10% of the cropped area, limiting fire exposure compared with whole-land burning. "For a farmer who is worried about affecting soil health, narrow windrow burning is a better option than burning the whole land," she says. Farmers need burning permits.

These are harvest weed seed control practices, developed extensively in Australia against herbicide-resistant annual ryegrass. The Harrington Seed Destructor, an impact mill that pulverises seed in the chaff fraction, is also being investigated at Stellenbosch: chaff will be collected, milled and returned to trial plots to simulate the mill under Western Cape grain conditions.

Can livestock and crops do the weeding?

"Livestock not only allows farmers to diversify their income, but are excellent weed eliminators," says Bestbier, who has seen grazing reduce ryegrass in her own sheep-in-medic-wheat-rotation research. Timing is critical — seed can survive digestion and spread in dung, so animals must graze weeds before they set seed. Baling offers a compaction-free alternative; Australian bale-direct systems attach a baler to the harvester so weed-seed-laden chaff becomes saleable feed.

Crop competition matters too. A vigorous cultivar planted at higher density closes canopy faster and competes for light, water, nutrients and space. "You want your crop to outcompete the weeds," she says. Cover-crop mixtures work on the same principle, and may help displace ryegrass, which is not indigenous to South Africa — especially where resistant plants carry a fitness penalty. Resistant plants still need controlling before flowering, since resistance spreads through pollen.

How far has precision spraying come?

Nico Myburgh, CNH head of precision technologies for the Middle East and Africa, says precision spraying has evolved significantly in 15 years. Section control cuts chemical wastage by about 5% to 10%. The next step, individual-nozzle control, is here: Raven's Hawkeye 2 system controls up to 192 nozzles separately and holds application within about 5% of target rate. Systems such as Augenta — the foundation of CNH SenseApply — use cab-mounted multispectral cameras and AI to adjust applications in real time. "The sprayer effectively becomes its own scouting platform," says Myburgh. "The industry is moving from spraying fields to treating individual plants."

Selective spraying does not mean weaker doses — recommended rates stay where weeds occur, and savings come from leaving clean ground untreated. Even a 10% to 20% chemical reduction justifies the business case where programmes cost several hundred rand per hectare. Within five years, Myburgh expects closer satellite-drone-ground integration and better plant identification.

When does WeedSAT pay?

Tiaan Venter, co-founder of FarmLink Capital — local implementation partner for Australia's Datafarming — calls WeedSAT "essentially a weed prescription-map generator". It detects weeds 30cm or larger using green-on-brown detection, suited to post-harvest, pre-plant or shortly-after-plant control, and loads onto any section-control sprayer without extra sensors. "I will stick to blanket control if you still have to manage weed in 80% of the land," he says. Australian users report up to 80% spraying-cost cuts; South African testing points to 50% to 60%. Australian pricing runs A$4 to A$7/ha (about R46 to R81/ha); local pricing, on a sliding scale, is not finalised.