Mildew is among the major concerns of the gardener because it can affect all types of plants, from garden vegetables to ornamental plants in pots or in the ground. In some cases, we can even speak ofepidemic as the problem is important, especially for market gardeners for example. This term refers to several maladies cryptogamiques formidable if one does not react from the very first manifestations. Fortunately, there are treatments against mildew but also simple solutions to adopt on a daily basis to prevent its appearance. Let’s take stock, not without having first drawn up a summary portrait of mildew.
Peculiarities of downy mildew
Different cryptogamic diseases are designated by the generic term downy mildew. They are caused by fungal microorganisms. These parasites are among the Oomycètes and have many similarities with pathogenic fungi.
The main symptoms presented by the affected plants are:
- Cottony-looking, white-colored moulds,
- brown spots,
- The wilting of any affected part, whether it is a stem, a twig, a few leaves or all of the foliage, the tuber, the fruit, then the whole plant,
- rapid rotting,
- A powerful smell.
The plant affected by downy mildew sees its growth disturbed. In the absence of treatment, it is doomed to certain death and the disease attacks other plants.
Natural mildew treatments
We have a whole arsenal of fungicides to fight against a mildew attack, but rather than opting for a chemical product, it is better to use natural solutions such as:
- The Bordeaux mixture : it is preferably used just after a heavy rain because this type of bad weather favors mildew. But beware, Bordeaux mixture modifies the Hydrogen potential of the soil (pH), which can be extremely detrimental for crops. It is therefore recommended to use it with great moderation.
- The Tanaisie : it must be sprayed on the plants. The preparation consists in infusing 200 g of Tansy flowers (Tanacetum vulgare) in 2 liters of boiling water. It is of course necessary to wait for the perfect cooling of this potion before treating the subjects affected by mildew.
- The black soap (2 teaspoons) combined withoregano essential oil (40 drops), all mixed first in 30 cl of lukewarm water then added to 2 liters of non-calcareous water where care has been taken to dilute 4 teaspoons ofclay green or white. This anti-mildew preparation is used cold, in sprays.
- From black soap (20 ml) combined with bicarbonate de sodium (5 g) in 2 liters of water, to be sprayed on the plants, knowing that after a rain it is necessary to process again.
Before embarking on one or the other of these homemade recipes which have proven their worth, it is imperative to ensure beforehand that it is perfectly suitable for the plants concerned, and how often to apply the treatment. However, we can be reassured since these four remedies do not present any particular toxicity for plants. We can also cross our fingers that the outside temperature will skyrocket, the hot weather overcoming mildew in record time. The reason is simple: during a heat wave, there is hardly any humidity in the air and the ground is dry.
Prevent mildew to protect your plants
When you want to have a productive vegetable garden or a beautiful pleasure garden, you have to know how to treat your plants quickly in case of mildew. This is fundamental because the different cryptogamic diseases referred to by this generic name can affect potatoes, tomatoes, eggplants, peppers, chervil, lettuce, onions, spinach, melon or the vine. In the pleasure garden, many plants do not escape it either, as is the case with wallflower, fragrant alyssum or even sweet peas, among others.
A few days may be sufficient for ruin all efforts if mildew is rampant, you might as well not give it the opportunity to settle. The gardener therefore has every interest in taking good gardening habits in order to play the card of the prevention. To do this, he needs:
- Opt for the rotation des cultures so as not to grow the same plants several years in a row in the same place, especially all those that are susceptible to downy mildew.
- plant resistant varieties.
- Carry out reasoned wateringexcess humidity being a factor that seriously favors cryptogamic diseases.
- Space the plants sufficiently in order to allow the air to circulate properly, the confinement of the plants increasing the humidity rate.
If we grow vineit is strongly recommended to carry out a manure spray horsetail as a preventive measure. Effective on the vine, this solution does not seem to have the expected effect on other plants.
Of course, it is also very useful to learn to spot the first signs of mildew to act without delay by cutting off all the affected parts that should then be burn, in order to prevent the spread of the disease. This plant debris must in no case be inserted into the compost of course, because the spores remain there very well and the next spreading, this would only result in infecting the plantations.
Downy mildew should not be treated lightly because the damage it causes are very important. Moreover, we cannot evoke it without recalling the ravages which he trained in large potato crops in Ireland between 1845 and 1849, responsible for the ” Great Irish Famine which continued until 1951. But there, it was a terrible late blight epidemic and theannihilation of local cultures was almost total, creating a catastrophe on different levels: human first of all since it is estimated that a million people died from it, then economic and also cultural.