The olive tree is widespread in the south of France but can acclimatize itself pretty much anywhere. Although it is not common in our gardens due to its large size, we all use olive oil. We often add it to our vegetables; whether it be on salad, in food preparation, cooking or even in cosmetics. But did you know that as well as tasting good, olive oil is also good for you? In this article you will discover the benefits of olive oil, but don't forget that – as with everything – you shouldn't go overboard with it.
Olive oil is good for our health
First of all, if you aren't sure which olive oil to pick, it is best to choose cold-pressed, bio, extra-virgin olive oil. Above all, avoid refined and heated oils which are cancerogenic and harmful to health.
Olive oil contains oleic acid (56-83%), an acid which can reduce the highest cause of death: cardio-vascular disease.
It also contains as much linoleic acid (Omega 6) as breast milk; so you could put a spoonful of olive oil in your children's soup. Omegas 3 and 6 are essential fatty acids that we can't produce ourselves and that we can only get from our food.
However, beware of taking too much, as Omega 6 must always be balanced with Omega 3, which we often get too little of. You can find Omega 3 in fatty fish and certain fibres (flax, walnut, rapeseed, soya etc.)
What's more, olive oil has anti-oxidant properties (vitamins E, C and polyphenols) that prevent cancer, as these properties prevent the ageing of cells.
If you heat the oil, beware that it becomes cancerogenic at temperatures of more than 210c; so if your oil smokes, you must discard it.
Olive oil vs cow's milk
When we are cooking and want to add fat, we generally use butter from cow's milk, or oil. Although they are not the same from a taste perspective, and their use varies by region and cooking habits, you should know that olive oil is better for your health than butter.
Olive oil only contains 14% saturated fat, which is a lot less than margarine, which is around 40%, and butter, which contains 55%. Olive oil is the most easily digested fat: you can even use it instead of butter on your toast in the morning, if you place it in the freezer the night before.
In addition to being the most digestible, it has as much calcium as cow's milk, at 120mg per 100g; however, vegetable calcium is 75% absorbed by the digestive tract, as opposed to only 30% for animal calcium.
Olive tree flowers
Only one flower in 20 becomes an olive. Olive tree flowers can also be used for their energy: dried and in herbal tea. They are anti-cancerogenic, nourish the skin, can be used as a gentle laxative, for rheumatisms and are good for the brain.
Jardin Familial de France no. 502/2017
Well known amongst gardeners, it comes back every spring to feast on the aphids that parasitize our runner beans, tomatoes and even our broad beans. Ladybirds are familiar, but how much do we really know about them?
For example, did you know that this insect from the Coleoptera family lays clusters of around a hundred dark yellow eggs on the backs of leaves? Larvae are born from them, which shed their skin several times and – about 20 days later – turn into what is called an imago, which is its final form. It lives for around a year, perhaps more if those born in late spring can manage to hide somewhere to protect them from winter.
Ladybirds are essentially carnivorous. Even as larvae, their main menu is aphids, which they consume at a rate of around 100 a day. As an adult, the creature is just as voracious and is estimated to consume around 150 aphids a day but, real gastronomes, they don't turn their noses up at acarids and cochineals. So, they are true gardeners' helpers. Therefore it is a big mistake to use chemicals to get rid of aphids, as you will also get rid of the ladybirds. The consequence of this, as counter effect i.e. the lacking of ladybirds is that you will then never be able to stop using chemicals. It is better to let nature do its work and support having these insects in our gardens. You can do this by making them shelters made of twigs, small heaps of straw or dead leaves, a pile of flat stones or even to the extreme by installing "insect houses" sold in garden centres, which aren't deep enough to be efficient and are always more for aesthetic purposes (if you want to make one, it is better to use several planks of wood spaced 5mm apart). The important thing is that they can find a safe shelter to pass the winter; sheltered from frost, heavy rain and birds that hunt them. And if they find a shelter in your garden shed or garage, don't move them: they are inoffensive and will be ready to reproduce at the start of spring. They are insurance for a year without aphids.
It is generally thought that ladybirds are that small red insect with 7 black dots that used to be called "God's [little] cow". In fact, what is little known is that there are many types of ladybird: red, yellow, black, with two dots, 12, 17, and even 24 dots.
In around 1870 there were 36 species in Europe but pesticides, the loss of hedgerows, and intensive farming have meant that many of them have disappeared. In 1960 there were only 16 species. Today many are extinct. A fatal blow to the surviving species in the 1980s was the introduction of the Asian ladybird, an exotic species bred and sold to fight aphids in an environmentally-friendly (!) way. There are many types in an array of colours, but not always easy to distinguish from their European cousins. In fact, they are bigger, more voracious and even more prolific than our local species; they quickly acclimatised and made a large number of our traditional species disappear. They became the most widespread species of ladybird here; with an annoying tendency to invade our houses at the start of winter.
A particular peculiarity about the Asian ladybird: it bites! It doesn't do any harm, as the skin on our fingers is too thick for its little mandibles. But it's a surprise!
The Asian ladybird lives up to its name as the "aphid ogre"! But did our European species have really to pay the price of this invasion and see a shortage happen?
This is a question that concerns specialists and entomologists. For the majority of gardeners, a ladybird is a ladybird, and given that it gets rid of our aphids, we aren't too bothered about where it comes from.
Jardin Familial de France no. 502/2017
Let us take the International Organisation for Biological Control's definition: "human use of natural enemies such as predators, parasites or pathogens to control the population of harmful species and keep it below a harmful level."
What is a predator?
A predator is a living organism that captures other living organisms dubbed "prey" to nourish itself or its offspring. Here are some examples:
- Ladybirds: the larvae and adults are predators that prefer to eat aphids and the larvae of white flies and mites;
- Lacewings: the larvae attack aphids, and the adults feed on pollen and nectar;
- Seedcorn beetles: very polyphagous, the larvae and adults feed on a large range of pests: Colorado beetles, slugs, wireworms, chafers;
- Bedbugs: predators at all stages, they feed on mites, thrips etc;
- Syrphid flies: the larvae eat aphids, and the adults feed on pollen and nectar;
- Predatory mites: (Amblyseius, Phytoseiulus) they eat pests at all stages of their life (spider mites, thrips).
What is a parasitoid?
A parasitoid is a living organism that feeds, grows and reproduces on or inside another living organism but, contrary to parasites, inevitably kills its host. The majority of parasitoids are insects. Here are some examples:
- Micro-hymenoptera (parasitic wasps): they live on aphids, ringworm, noctuids, houseflies etc;
- Rove beetles: they prey on larvae and parasites of soil-inhabiting flies (cabbage fly, carrot fly, seed fly);
- Nematodes: they limit the numbers of fungus gnats, otiorhynchid larvae and slugs.
What is an auxiliary?
These are living organisms, predators or parasitoids that control or eliminate the enemies of the plants to be protected. Auxiliaries can be specialist (prey or hosts) or polyphagous (diversified).
Pollinating insects are also considered to be auxiliaries in so much as they pollinate plant species. For example, the large earth bumblebee (Bombus terrestris) pollinates greenhouse tomatoes and seeds.
What is a pathogen?
This term refers to certain agents, bacteria or viruses, which attack insects that are a pest to plants. Mushrooms are equally capable of destroying other mushrooms. For example, Coniothyrium minitans in the fight against Sclerotinia. A number of other animals present in the garden environment are also auxiliaries to plants:
- Insectivorous birds: they feed on all insects, but particularly young caterpillars;
- Birds of prey and cats: very efficient at limiting the numbers of field mice and voles amongst plants;
- Dragonflies and spiders: great consumers of flying insects;
- Hedgehogs: they attack slug populations.
Setting up biological protection in the garden
This practice is based on the relationship between species in the environment, and aims more to manage the number of biological pests than to eradicate them. On the one hand, it is necessary to know the pest/auxiliary combinations that are potentially present in the garden; and on the other hand, the bio-control products that are available.
The aim is to protect plants rather than fight their enemies. It is about searching for allies to act with nature and not harm it.
The new concept of gardening
Its spatial organisation may or may not facilitate the connection between the different garden environments and between different gardens. The garden is not isolated, its protection is an integral part of the land on which it is situated. It is absolutely essential to create links from garden to garden with low hedges, for example. Here we are introducing a new concept: that of the integrated protection of garden plants, "the setting up by the gardener of a coherent collection of direct and indirect means to minimise the competitors for growth". Here are some example methods:
- Growth control: prophylaxis, ways of growing (size, fertilizer), growing techniques;
- Genetic control: varieties or rootstocks that are resistant or insensitive to biological pests;
- Biological fight by conservation: preserving auxiliaries;
- Biological fight by increase: massive releases of auxiliaries to enlarge the population;
- Biological fight by disruption: trapping through sexual pheromones;
- Physical fight: protecting nets, solarisation, bio-fumigation;
- Biological fight: micro-organisms, macro-organisms;
- Trap plants: plants that have an attractive or stimulating effect on a pest;
- Using natural substances: minerals (anti-slug iron phosphate), plants (vegetable extracts, manure) or animals (dried blood to repel game).
These new gardening methods really show us that we are at the crossroads between "synthetic" chemistry and "natural" chemistry. The latter cannot truly work unless we agree to change our practices and adopt the new ways.
Le Jardin Familial de France no. 501/2017