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
Legend and history
The word "Iris" comes from the Latin "iridis", which in turn comes from the Greek word "Iris, Iridos" meaning "a messenger from the Gods" which relay their messages to humans in the form of a rainbow. The word became associated with the flower at the start of the 13th century due to the colour of its petals, with iridescent hues. Already considered sacred by the Egyptians, it became the symbol of royalty in France under the name "fleur-de-lis". It appears that the use of iris as a perfume was started by Catherine de Médicis.
The iris (in French, the flower is a masculine noun, but a feminine name) is a root or bulbous perennial plant from the iridaceae family (like the crocus). The iris group contains some 120 species and innumerable horticultural varieties, without counting sub-types. In our gardens you find hybrid horticultural irises known as the German or bearded iris.
• The leaves alternate around a sheath, almost always sword-like.
• The flower: large grouped hermaphrodite flowers, grouped in bracts known as spathes (like tissue paper), then opening into six tepaloid tepals that seem to be in two rows: the flower is made up of three external, horizontal tepals (or sepals) which support a beard and three smaller, upright, internal tepals (or petals).
• The fruit is a capsule of three compartments containing various seeds. You can dry the seeds and plant them.
The iridologist has a very particular vernacular, with no less than 23 terms, for talking about iris flowers according to the different flower colours, their shape and the plant's height. There are two categories of iris:
• Those without a beard (Louisiana iris, Siberian iris, Californian iris, blue iris, Japanese iris)
• Those with a beard, the majority of irises in our gardens, regardless of height.
The iris flower has evolved greatly over the course of the 20th century thanks to breeders: from a smaller type, narrow and soft, they have come to produce tall flowers, less fragile, in rich colours. They have also brought improvements to the flower's shape itself: wavy petals, curly, wider, harmonised the dimensions of the sepals and petals and other fantasies: rustles, spurs...The shape of the iris is not fixed; the breeders may well find a way one day to turn the spurs into true petals.
The iris in our gardens
The most common iris in our gardens, the bearded or German iris, is found in a variety of colours, from pale blue to violet/black, from white to yellow/orange/copper/chocolate brown, except red even though sometimes the spurs are a vivid and dark orange. We have a large choice with regards to the height of the plant and flowering season:
• Iris lutescens (rhizomatous) – 15-30 cm – March to early April
• Dutch iris (bulbous) – 70-100 cm – April-May
• German iris (rhizomatous) – 70-100 cm – end of May to early June
The duration of the flowering season obviously depends on the number of flower buds on each stem; few irises are still up at the end of summer.
Where to plant them?
• In the South, the iris will tolerate slight shade. Elsewhere, they are only happy in full sunlight, failing that in sun for half the day.
• They don't like being planted at the foot of trees or shrubs where the roots deprive them of nourishment.
• All types of soil suit the iris, but in a heavy, dense soil it is preferable to plant them on a mound of 5-15 cm after adding sand.
When to plant or move them?
• The summer months are preferable, from July to October, so as to have the time to establish themselves and have the best first flowering season.
• In the North and East, planting late from February to mid-June is not advised.
• To move them: every 3-4 years, in summer, removing the oldest, damaged, dried part of the root. How to plant them?
• For the best results, 3.5-7 ft per tuft according to your garden, the neck of the root facing inwards, the green shoot facing towards the outside of the circle.
• The roots should not be covered with more than 1-2 cm of light soil, so that they can be seen when the soil is turned.
• The roots will be well-placed flat, covered with earth with copious irrigation.
• If you plant a lot of them, straightaway make a run-off with a hoe of 5 cm deep and 20 cm long; on one side, prick the roots and patch them.
• They don't like weeds, humidity or excess water: they only need water when being planted; only water them in case of drought or prolonged dry weather.
• Cut the stems 10 cm above soil level after they have flowered and don't cut the summer leaves unless they are too spotted (don't put them in the compost).
• Cut the leaves in mid-September to early October (but all theories have their shortcomings...). But what happens is you get the most beautiful season for enjoying their multicoloured flowers and their scent after the Ice Saints.
Jardin Familial de France no. 501/2017
The genus Ipomoea consists of around 500 species of twining vine, bushes or trees from the Convolvulaceae family. Some studies (D. Austin, 1997) have listed between 600 and 700 species, of which over half originate from North and South America.
• First there is the Ipomoea purpurea, very well suited to for the temperate climate: it is an American climbing plant whose blue-purple aspect is widely known and which the Americans call Gandpa Ott. The pink flower is also known in Europe.
• The ipomoea tricolor (ipomoea tricolor or morning glory) originates from Mexico and Central America. In that region the flower is known as badoh negro and its seeds have been used as hallucinogenics since the Aztec era. It is grown the entire year and puts out a good number of blue flowers – really blue! – of around 10-15 cm. Their highlight is a yellow center.
• The ipomoea nil came from Japan some 1,000 years ago from China. At the time it was used as a diuretic; the Chinese had obtained it from the Arabs who traded with all the small kingdoms of East Africa. The Nil arrived accompanied by other Ipomoeas, including one from the Himalayas and another from the Beijing area. They quickly appeared in gardens and were crossed with each other to obtain different colors. They went from being bluish, to pink then white, and are known in Europe as "ipomoea purpurea" and tricolors. One that is much less so is the Japanese ipomoea, "ipomoea nil" or "Asagao".
These flowers found their way into Japanese poetry because they represent a strong theme in Japanese culture: life is short, as is beauty. The Ipomoea opens at day break and by late morning already begins to fade. Some colors and shapes were very rare and were thus very costly. All of the various dynasties loved them. There were rivalries between towns and even today ipomoea exhibitions are held in the summer. Collectors post photos of their extraordinary results on the internet. Every year from 6 to 8 July, the Japanese hold the Ipomoea Festive in Iriya, where some 120 merchants exhibit to 400,000 visitors from all over the world.
Over the years in my garden I have experimented with all the different types of ipomoeas. Seedlings may be sown after soaking in a sheltered setting from March to April at 16°C, or in the ground between April and May after the danger of frost is past. Standard ranges of pink, red, purple and white ipomoeas can follow this schedule.
Contrary to the recommendations of seed producers, the climate in the north of France calls for sowing light blue, bright blue and striated ipomoeas (the "flying saucer", "Ismay" and "Venice Carnival") ipomoeas as late as possible in May since they have difficulty starting out. However, they flower up through the end of October if clement weather persists.
The superb and enormous white, fragrant ipomoea "Moonflower" with abundant foliage requires more care, and above all, warmth from the start. It never really flowered except during two or three very warm summers or during heat waves, perfuming the garden at twilight through to the morning.
The Mount Fiji Japanese ipomoeas featuring pastel tones or in contrast very sharp colors of pale blue, a blue-violet that is nearly ultramarine, pale pink, fuchsia pink or old pink, are splendid flowers ringed with white edges. Growing these requires a green thumb as they are sensitive to the cold and it is better to keep them in the greenhouse and/or sow them from mid-June to mid-July. Specialists even germinate them three or four days at 28°C. They don't do well with heavy northern rainfall.
In the Paris region, I now prefer to plant them in large pots that I bring inside immediately when the temperature falls in September or October. These are species that cross breed with each other from one season to the next, producing different shapes and colors.
Watch out for slugs, who love the whole range of the species, beginning with the young shoot stage.