Herbs and plants that repel pests and annoying insects

Aphids can cause enormous damage in the home garden.
Aphids can cause enormous damage in the home garden.

Many gardeners know this problem: With great difficulty the own garden is dug up, planted, freed from weeds and fertilized. Out of nowhere, pests suddenly start to enjoy flowers, vegetables and fruit plants. These include, among others, snails, aphids, thrips, fungi, mites or caterpillars. There are plenty of insecticides to buy from garden shops that one may help, while others are rather useless. But why always use the chemical mace, though there are ways to control the pests naturally?

Effective ingredients keep pests away

Surely you will wonder what is so special about herbs and why they should just keep pests away. To answer this question satisfactorily, one has to deal a little bit with the ingredients of the herbs and their existence.

Nature has established that almost every species has evolved certain defenses in the course of evolution in order to survive. This applies to the plant world as well as to the animal world. A simple example from the animal world is the wasp. If the wasp did not have its defense sting, it would be an easy prey for many insectivorous animals. So their sting protects them from many predators.

Similar to the animals, many plants protect themselves from natural enemies. Some plants have rather external protective mechanisms, such as e.g. the rose or hawthorn, which have developed thorns, e.g. to be spared by larger herbivores such as cows or goats. Other plants, including many herbs, have special ingredients that protect them from natural enemies. These ingredients can have very different effects. Some substances repel insects by their scent, other substances are poisonous and lead the natural enemy injury or even death. However, there are also ingredients that are simply inedible for insects, for example.

Plants like nettles and some herbs are quite efficient

A well-known herb with effective ingredients is the nettle. Everyone knows the annoying burning that comes back when you’re stroking your bare skin over the plant. If you look more closely at a stinging nettle, the hastate stinging hairs will immediately catch the eye. These stinging hairs look more like a medical syringe. These hairs are filled with methanoic acid (formic acid), acetylcholine, histamine and serotonin and cause a burning pain when touched. By the way, the substance acetylcholine is responsible for the pain. After a short time wheals form on the skin, which disappear after some time.

The active ingredients found in herbs include among others, the tannins and the ellagitannins. These cause a bitter taste that most insects do not like. Also highly effective substances against natural enemies include the glucosinolates. These taste sharp, smell pungent and also release other toxic substances (so-called isothiocyanates).

Some plants even have ingredients that can inhibit or stop the multiplikation of microorganisms such as fungi or bacteria. These substances, called phytolexins, are produced by the plant immediately after infection with microorganisms. The phytolexins include groups of substances such as flavonoids, alkaloids or isoflavones. Exactly these substances are, by the way, among others responsible for the healing power of some herbs.

The control of caterpillars can often be done in the garden with simple means.
The control of caterpillars can often be done in the garden with simple means.

Herbs against pests

Mediterranean herbs

Some Mediterranean herbs such as lavender, oregano, sage and thyme release fragrances that deter pests such as aphids. For example, herbs like lavender are often planted in the vicinity of roses to repel aphids. Responsible here are the essential oils of lavender.

Sage on the other hand helps against unwelcome guests such as cabbage white butterfly, caterpillars, snails and sometimes also against aphids. Sage (Salvia officinalis) is used in some natural gardens especially as a natural defense against snails that do not like the aroma of the herb. Here it is above all substances such as the thujone, which the pests do not like.

Herbs against mildew

Admittedly, the mildew can not be combated by herbs. However, through targeted planting one can ensure that it does not even arise. Suitable herbs and plants are chervil, garlic and chives. If you have to complain about fragile plants every year, you can, for example, plant chives in between. Inasmuch as mildew is not yet well advanced, planting chives or garlic in the immediate vicinity of the affected plant is still worth a try. Basically, you should refrain from all nitrogen fertilization in infestation with mildew, as you support the fungi through this a lot. Many fungi such as mildew or rust are usually also an indicator that the soils are slightly overfertilized.

Use fresh milk instead of fungicides against powdery mildew

As an environmentally friendly remedy for powdery mildew is milk. The microorganisms contained therein fight the mildew fungus. The contained sodium phosphate also strengthens the plants defenses and thus prevents new disease due to powdery mildew. Make a mixture of milk and water in a ratio of 1: 8 twice a week and spray the infested plants with it. This method has now been tested. It has even been found that milk is often more effective than commercial fungicides.

Important: Use milk that is as fresh as possible, because the microorganisms do the work and should still be “alive” in the milk. The most suitable is raw milk directly from the farmer, which is available in the health food store or from the milk filling station.

Cut leaves that have already infested from mildew and collect them from the ground so the fungus does not re-enter the natural cycle. Infested leaves belong in the trash can – not on the compost.

stinging nettle
stinging nettle

Herbal swill and herbal extracts with nettle

Nettle dung water and nettle extracts are used quite frequently in some gardens. They are considered to be excellent natural pesticides, which can be used for many applications. The manure acts as a deterrent on many insects, including aphids, thrips and caterpillars. For the production of a manure, about 1 kg (2 lbs) of nettle leaves should be placed in 10 liters (30 fl.oz) of water in a bucket. The mixture should stay in the bucket until the foam dissolves and the water has assumed a rather dark color. In order to minimize the smell, which inevitably arises, primary rock flour or zeolite flour are outstandingly suitable.

In order to apply the herbs on the plants, they must be diluted. Pure manure can also cause damage to their plants. The best mixing ratio is usually 1:10, i. on 1 unit of manure come 10 units of water. The manure can be used as irrigation water and be applied directly to the plants.

Please keep in mind that not only do you use effective plant protection, but also use a low nitrogen fertilizer. Stinging nettles are rich in nitrogen. You should always keep this in mind when using it, as it can lead to over-fertilization if used improperly. Then maybe the pests are gone, but also your plants.

Incidentally, other plants such as the field horsetail suit for the production of swill, broths and extracts.

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