Kill weedkiller grass

weed killer

Origin and history

The ancient Romans had to struggle with weeds, but weed killers have only replaced the laborious manual work of hoeing and weeding since the middle of the 19th century. First, iron sulfate or sulfuric acid was let loose on weeds as herbicides, and in the 1920s, sodium chlorate, which was long sold as "WeedEx", was also released. The impact on the environment was secondary, you saw mostly the success.

The highly effective compound called 2,4-D has existed since the 1940s and is still contained in lawn weed remedies today and only combats dicotyledonous weeds. To this day, many substances have been added that are approved as weed killers in the home garden. They came into the discussion for the first time through the massive deployment in the Vietnam War, where close relatives of 2,4-D as "Agent Orange" destroyed entire rainforest areas and caused massive damage to people due to contamination with dioxins. Thanks to stricter environmental regulations and increased awareness, more and more funds are being put to the test today.

How weed killers work

Most weed killers act as contact herbicides on or over the green leaves. With so-called caustic agents you can almost see how the leaves wither within a short time, leaves that are not wetted remain intact. The result is like a chemical weed hoe that removes all parts of the plant above ground like a hoe. Annual weeds usually die completely, but root weeds sprout again after a while. Since the spray liquid has to dry off on the leaf and must not be washed off, dry weather accelerates and improves the effect. The active ingredient remains outside the plant or is absorbed locally by the leaf at best. Leaf burns are effective even at low temperatures below ten degrees.

Systemic agents are absorbed by the plant after the green leaves have been wetted, but then transported with the flow of sap into all parts of the plant - even into unaffected leaf areas and the root tips. The agents hinder the metabolism and are therefore also called growth substance herbicides. The result is a complete destruction of the plant, whose metabolism is overpowered until it dies - it grows to death. However, you only see success after days. Since the plants have to work actively to transport the active ingredients, the agents only work reliably at higher temperatures, and they work best in humid growth weather. Glyphosate, which has come under discussion, is one of these agents.

So-called soil herbicides fight dormant seeds. The remedies are of little importance in the garden, but are often part of lawn herbicides, some of which work through the roots.

Most weed killers do not distinguish between good and bad and go for anything green at random. These total herbicides should only be used if there is sufficient distance between weeds and crops, if the crops can be covered in the bed or if there is no wind. There are only a few selectively acting herbicides. The 2,4-D mentioned at the beginning, for example, allows monocot plants to stand, including grasses.

Weed killer with biological agents

Even if herbicides are not permitted in organic farming, there are agents for home gardens with natural or nature-based active ingredients such as acetic acid or pelargonic acid. The best known are "Finalsan AF WeedFree Plus" (Neudorff) with the active ingredient mix of pelargonic acid and maleic acid hydrazide, the "Organic weed killer Herbistop AF" from Compo with pelargonic acid and "Celaflor NaturenBio weed-free" based on acetic acid.

Chemical weed killers

Whether 2,4-D, MCPA, dicamba or glyphosate: That sounds somehow poisonous and "Agent Orange" often still haunts the back of the mind: The chemical weed killers like Roundup & Co. have fallen into disrepute the most, but they also work on the and eliminate weeds almost completely with just one application. Glyphosate was developed by Monsanto and has been on the market as "Roundup" since 1974. It is now sold by more than 40 companies and is partly contained in other weed killers such as "Vorox Weed-Free Direct".

Lawn herbicides

If the green carpet is riddled with weeds, lawn herbicides can help. They leave the grass alone and only attack the dicotyledon weeds. However, this means that couch grass and chicken millet are also spared. Lawn herbicides are sprayed or watered, where spraying is faster and uses less agent. The weeds turn brown after a few days and seem to literally vanish into thin air.

The prerequisite for a good effect are (night) temperatures of over ten degrees. If it is colder, the plants are much too sluggish and do not transport the active ingredients to the root tips. Mow the lawn beforehand and then wait four days until the treatment so that the cuts on the stalks close.

Tip: Weeds can be prevented with high-quality lawn mixtures. They are more expensive, but save trouble and follow-up costs. Branded seeds form a much denser lawn in which weed seeds hardly find any gaps to germinate. The cheap mixes grow well in the first year, maybe in the second as well. But then their forage grasses show their true colors: No dense scar, but gaps. Then the previously price-conscious hobby gardeners start to invest a lot of money in care products and equipment, which then only temporarily eliminate the symptoms - the weed growth.

Calcium cyanamide against weeds and seeds

Calcium cyanamide is a nitrogen fertilizer that is sold as "Perlka". In addition to being a fertilizer, it is also a weed killer and even kills weed seeds. The effect is based on the cyanamide, which is formed in the moist soil. It is not a highly toxic cyanide, even if it sounds similar. Cyanamide has a caustic effect and also kills low lawn weeds, but if the wrong dose is used, it also kills the grasses. In the soil, cyanamide is first converted to urea and then to the plant nutrient nitrate.

The poor dosage option makes calcium cyanamide unsuitable for lawn fertilization and thus for combating lawn weeds. As a basic fertilizer for seed beds, however, it is ideal, because the bed then goes into weed-free season after two weeks. This is roughly how long it takes for cyanamide to be completely converted into harmless urea.

Proper handling of herbicides

Weed killers are available as a concentrate to dilute or as a ready-to-use agent (AF) that can be poured or sprayed immediately - watering is faster and is particularly suitable for small areas. In contrast, spraying consumes less of the agent. After the treatment, it should stay dry for a few hours so that the active ingredients are not washed off again. Never spray in windy conditions, as the drift can damage adjacent beds. Residual amounts in the syringe must be sprayed onto the surface again, they must never end up in the sink!

Weed killers only fight weeds with sufficient leaf mass. Even if it is difficult, ground grass & Co. have to be allowed to grow until they have enough leaf surface. Then you spray them dripping wet. It should go without saying that pets do not get any spray mist. These are only allowed into the garden when the spray coating has dried off. Root weeds often come back again, as there are always some pieces of root that have not been sprouted, which are therefore spared. After another treatment two weeks later, the weeds are defeated.

The lawn must be dry for spraying lawn herbicides. When applying, go backwards so that you do not step on the treated area and the agent may collect on your rubber boots elsewhere, where it is undesirable. Clean used syringes immediately after treatment, because even small residues can damage subsequent cultures.

Prohibited Uses

Herbicides that are applied in house or allotment gardens must be approved for this area of ​​application. The large containers for professional horticulture or agriculture sold in the agricultural trade do not have this approval and may not be purchased or used by persons without corresponding proof of expertise - for example, a professional training as a gardener or farmer. If, on the other hand, you entrust a landscaping company with gardening, they can also use products for professional horticulture in the home garden.

According to the current state of science, there is no fear of damage to the groundwater due to the strict tests carried out in the course of the approval process for plant protection products - but only if the products are used correctly. It is mostly the application errors and excessive use of crops that repeatedly get herbicides into the sewer system and finally end up in the sewage treatment plant, where they cannot be broken down. This only works on "biologically active" areas, which is why herbicides can only be used on cultivated areas such as beds or lawns.

One thing is temptingly convenient, but absolutely forbidden: weed killers on paved surfaces and other sealed surfaces. It is essential to follow the instructions for use with regard to dosage and application period. A violation can be subject to a five-digit fine. The risk of getting caught may be small, but many municipalities are now even sending employees out to check it out in the evening. Hardly any of those caught pays the full legal penalty of 50,000 euros, but even the realistic fines of a good 8,000 euros are not worth a violation.

There are also numerous suggestions and recipes for home-made home remedies circulating on the Internet, for example made from vinegar, salt or other supposedly biological ingredients. According to the Plant Protection Act, every plant protection product, including a weed killer, must be approved for every area of ​​application. The self-mixed broths are basically not. On the one hand, you are applying a product as a plant protection product that is not at all, and on the other hand, a preparation that is not approved for the intended use - a double administrative offense.

If you really want it organic, you can pour boiling water from the kettle over the weeds, give it a heat shock with a flame device or simply pull it out of the ground manually.

Weed killers should always be the last option

For many hobby gardeners, only weed-free gardens are beautiful, and without any work, please. The most thorough and environmentally friendly weed control is and remains manual work. And why not leave a few weeds next to the compost or in another corner? Insects are happy about the nectar fast food and the garden doesn't have to look neglected because of it.

Even if the Federal Office for Consumer Protection and Food Safety (BVL), as the licensing authority, thoroughly tests every plant protection product and the residual amounts are well below a limit value even when handled properly, you do not want glyphosate or other active ingredients - via whatever detours - in your food. But ultimately every hobby gardener has to decide for himself whether he wants the admittedly convenient chemistry in the garden or not.