Farmers first used cultivation to mechanically kill weeds: hand hoeing, pulling weeds, then horse- and tractor-driven cultivators. Then they started using chemicals, starting with 2-4D, to chemically kill broadleaf weeds. New chemicals were developed, and then glyphosate (Roundup) emerged as the most popular herbicide, especially after the introduction of glyphosate-resistant genes into many crops. But like all innovations, they will be replaced sooner or later due to limitations.

Cultivation disturbs the soil and takes a lot of fuel and time. Every time you disturb the soil, you replant weed seeds and lose carbon in the form of soil organic matter. There can be as many as several hundred thousand weed seeds per square yard in soil. This weed seed can remain viable for a few years, a decade, or even longer. Weed seeds with thicker coats and buried deep with tillage survive longer than those left on the soil surface with no-till. With chemical herbicides, herbicide-resistant weeds are now a problem, and herbicides may be toxic to beneficial plants, animals, and humans.

New innovations in weed control are becoming a reality. First, electroshock uses onboard generators to pass electricity through plants. Electricity destroys chlorophyll and cell walls in the vascular system, causing plants to die from desiccation and drying out within hours. Onboard sensors can distinguish between weeds and a good crop. It is fast, moving across the field 3X faster than cultivation. A new product called Hybrid Herbicide is sometimes used to enhance the electrocution of weeds. It is a blend of humic acid, sugar, biochar, and oil esters that allows electrons to penetrate the plant more effectively for a more complete kill. It is sprayed onto the plant just before electricity passes through it.

Lasers attached to computers using AI can recognize weeds and zap them as the machine moves across the field. Often, they are put on robotic weed zappers called Laser Weeders, which can operate within 1 millimeter (a hair’s width) of beneficial crops. Vegetable growers are using this innovation. It may also be used to fight invasive weeds like Palmer amaranth and marestail in the Midwest. The payback is about one to three years due to reduced hand weeding and reduced herbicide costs.

Farmers can now also use “Blue Light,” which is a machine attached to their combine that hits weed seed with Directed Energy (DE) light waves. Called the Weed Seed Destroyer, the machine hits weed seed as it is being passed through the combine with an LED Blue light that inactivates weed seed germination. It takes 4 seconds and can reduce weed seed germination by 97% to 99%. The same technology can be used to increase crop seed germination by using 50% LED light, and some of the same technology is being used to kill cover crops as a burn down.

Another way that technology is helping farmers reduce their reliance on chemical herbicides is through AI and onboard sensors. The sensors and AI detect weeds growing with the crops and spray just the weeds, reducing chemical application rates. This variable-rate technology can reduce herbicide use by up to 87% to 94%. Some systems report a 7% improvement in weed control over a typical broadcast spray. Why? Because the spot spraying hits the weeds more intensely, even at different angles, using smart computer-driven AI systems. Multiple nozzles, different angles, and even different sprays can be controlled with the computer to spray troublesome weeds to kill them effectively. Some of these rigs can even be operated at night.

Small mechanical robotic weed eaters are also being developed. These self-propelled robots use spinning blades and are used in corn, wide row soybeans, and cotton. They operate at about 1 acre per hour. Farmers can rent the machine, and usually 10 machines operate at the same time. They run on batteries for 4-8 hours, and a service man comes with the rental fee. It saves the farmer money by not having to buy the machine and gives the farmer flexibility. The robots weigh about 350 pounds each and are guided by Lidar (topography), RTK satellite signals, and AI. It’s much cheaper than herbicides in some cases, depending on weed intensity. These machines can be used multiple ways, including preplant, postplant, and after a burn-down chemical treatment, offering the farmer a lot of flexibility.

On a final note, a small amount of ethylene enhances germination of weed and crop seeds. Spraying with ethylene can get most weeds to germinate, and then they can be mostly terminated all at once. Much of this information was originally reported by Dan Crummett for No-Till Farmer and is summarized here for readers.