Farming comes with a lot of pride, pride in how you look after your livestock and pride in how you care for your land. This pride can give you a real big headache when weeds start to spread, thus adding to the ever-growing list of chores.

Weeds are so unwanted that you find ways to manage and control their growth. By understanding how to control and manage weeds, you can reduce the mental burden of dealing with them.

In this article, we'll discuss weed control methods, notably:

1. Why control weed growth?

2. General categories of weed control methods

3. Methods to control your weeds?

Weed control method using a tractor to spray chemicals onto a paddock.

Why control weed growth?

Weeds affect the growth of plants surrounding them by competing for nutrients, soil, water, and space. In cases of younger or smaller plants, some weeds even overpower their young plant parts.

Weeds not only affect the plants around them, but they can bring unnecessary trouble to the entire farm. For one, some types of weeds block drainage pipes, while some weeds, if left unchecked, may obstruct the function of farm machinery that is used for cultivation. Matter of fact, weeds can cause more manual labour for farmers like yourself.

If left uncontrolled, weeds may become hosts for various plant diseases and pests that will cause you a more significant headache.

The infamous weed: thistle.

General categories of weed control methods.

1. Preventive Methods of Weed Control

In weed management, prevention is crucial. A weed infestation that has gone array and has increased over time may require more expensive control methods. Any method that prevents the establishment of weeds in a pasture or across a farm is considered preventive weed control.

2. Cultural Methods to Control Weed Growth

Weeds are considered opportunistic and invasive; that is why cultural control or the establishment of a competitive and desired vegetation helps prevent or at least slow down the growth of weeds. Cultural control is considered highly effective in weed management.

3. Chemical Methods of Weed Growth Control

The use or application of chemicals (herbicide) to weeds or soil to control weed growth is called chemical weed control. Herbicides are considered the most effective and time-efficient method of weed control. Some herbicides are formulated so as not to cause harm to the surrounding plants of the weed. Chemical control is an effective way of controlling weeds. Currently, there are many chemical products available on the market for this control.

4. Biological Methods to Control Weed Growth

Any technique involving the use of living agents that are natural suppressors of weed growth is known as biological weed control. Living agents, such as grazing animals, insects, fungi, or bacteria, are being used not only to eradicate weeds but also to control the germination of its seeds. Insects are often utilised in biological weed control, with some naming this practice as insect bio-control or integrated pest management (IPM). Among many insects used in IPM, are a cinnabar moth, tansy flea beetle, and chrysolira beetle.

5. Manual/Mechanical Methods of Weed Growth Control

Physical disruption with the use of farm equipment or through physical actions is under mechanical weed control. The success of methods under this category varies depending on the life cycle of the target weed species.

We've now discussed the various categories or means that we can use to maintain weed control. Let's proceed to the many mechanical methods you may consider implementing in your pasture or across your farm.

Pasture full of weeds, most notably thistles.

Methods to control your weeds

Mowing and Cutting

Mowing and cutting can decelerate the production of seed and can limit the growth of weeds. Especially when the work is completed before the weeds flower and sets seed. However, this does not apply to all plants. There are some weed species that re-sprout abundantly and continuously when cut, making the plant set seed and flower faster than usual.

An example of this is the yellow starthistle (Centaurea solstitialis). Mowing is an effective method of controlling this weed, especially when there is approximately 2-5% flowering. However, if this particular weed is mowed earlier, it can re-sprout quickly.

How? Mowing and cutting can be done as primary treatments alongside herbicide applications to get rid of aboveground biomass. Just make sure that you collect and stash away the cut or mowed parts of the weed species that are capable of re-sprouting from the stem or root segments. This way, you're assured that the cut or mowed parts of the weeds will not infest the other areas of your pasture.

Weed Pulling

Uprooting plants by pulling is another effective method to prevent the spread of herbaceous and floating weeds. This is also effective in some shrubs, annuals, and tap-rooted plants. If you're quite hesitant to do it by hand, weed wrenches can be powerful tools to use. This is especially handy (excuse the pun) when you're trying to get a hold of large saplings and shrubs that are too big to be pulled manually. However, weed wrenches are not as effective against many perennial weeds whose stems are buried deep underground and whose roots re-sprout when left behind.

Some of the advantages of pulling include the minimal damage caused to surrounding plants, small ecological impact, and the low cost. However, it can be tedious and labour intensive, and its effect may only be seen in relatively small areas.

There are two kinds of weed pulling methods, namely hand pulling and pulling using tools. Hand pulling is often used to manage weeds in small areas because it's easier to plan and implement. All that is required is that you remove the roots without too much soil disturbance. This kind of pulling is useful in places that cannot be applied with herbicide. Meanwhile, tools can be used in removing, by properly grip the stem and provide the necessary force to pull its root out.

How? Pull out weeds slowly and carefully to prevent soil disruption. Disturbing the soil may provide a place for weeds to germinate and grow. Always wear your gloves, long-sleeved shirt, and pants when hand pulling as some plants can cause irritation to the skin when crushed or broken.

Stabbing

Stabbing weeds can destroy their carbohydrate storage structure, which immediately starves them, leading to their weakening or death. This, however, depends on their species. The organs that contain this carbohydrate storage structure are located at the base of the stem under the soil.

How? Push a knife, pruning saw, or flat-nosed spade as far below as possible to sever a taproot. Prevent re-sprouting by ensuring that the taproot is severed below the root crown.

Mulching

Mulching is another method that can be done in relatively small areas. However, it can also stunt or stop the growth of the surrounding plants. It also cannot control some perennial weeds, especially those whose food reserves continue to grow despite the mulching.

How? You may use hay, grass cuts, or wood chips, among others, as mulch. Cover the ground with this or with other covers, like newspaper clippings. This can prevent sunlight from passing through the weeds for its nutrition.

Girdling

Cutting or chipping away several centimetres of the bark all around the trunk is how your girdle. When the cut is deep enough, the vascular cambium, which stores and moves the carbohydrates throughout the tree, is removed, thereby killing it. This process requires much less labour than mowing and cutting and will only kill the targeted weed.

How? Cut approximately three or more inch parallel lines around the tree trunk. You may use a saw, knife, or axe to make the cut enough, so it reaches the cambium. Be careful not to cut it too deep, as it may cause the tree to snap and fall then and there.

Tilling

Turning the soil over or tilling is often used in protecting agricultural crops from weeds. This method is usually applied in sites where soils are already severely disturbed. Tilling is best done when the earth remains dry, and best completed before weed seeds develop.

How? Turn over the soil and cut the weeds' roots at six inches to two feet. Then work the top six inches of the earth to control weeds.

Soil solarisation, as a form of weed control.

Soil Solarisation

Soil solarisation is the practice of increasing soil temperature until it kills the weeds. Soil solarisation helps release nutrients that are trapped in the soil while killing undesirable plants without the use of chemicals. Covering the earth, usually with black plastic, to catch solar radiation is how soil solarisation is done. However, doing this also affects the biological, physical, and chemical composition of the soil that may discourage the growth of other plants.

How? Use black plastic to trap infrared radiation for soil absorption, therefore keeping it hot. This can stop photosynthesis and can kill weeds just enough.

Flooding

Some pastures are luckily located in places where the water level or a river system or wetland can be manipulated. This is a situation where flooding, another weed control method can be done. However, some weed species have underground storage organs or vegetative buds, which enable them to live through flooded conditions even for months.

How? Flooding is done by saturating an area with water at a depth of 15 to 30 centimetres. Soaking the soil this way blocks oxygen's entry to the roots, which effectively kills the weeds.

I do reply to every comment and would love to hear your experiences with weed control and which method you deploy in the comments below.

Happy farming!

- Ollie Roberts, 11 September 2019