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Vesta blog

Ardeur et Douceur


Mildew, the terror of the vegetable garden (ex aequo with slugs!)

Just like the oïdium, mildew is a fungus that spreads very quickly in humid weather, it is a frequent "disease" in the vegetable garden, and like powdery mildew, once installed, it is very very difficult to eradicate.

Again, the golden rule is prevention.

1/ How to recognize it?

The stems and petioles of the plants show brown spots, while the fruits struggle to ripen. In most cases, brown, mottled and firm bumps appear on the tomatoes. As for the leaves, they dry out in the center and have brown-green spots on the top and bottom.

2/ Preventive measures

- as for powdery mildew, space the plants well, for tomatoes, about 60 cm or even more if possible, especially if you do not prune the plants, plan for 80 cm, to guarantee a good aeration between the plants

- avoid that the leaves touch the ground and do not wet the foliage when watering

- avoid pruning tomatoes on rainy and humid days, which is in line with the advice given by Chloé, our market gardener, we will not prune the gourmands for plants planted outdoors, or only if the season is very dry, as pruning creates entry points for the fungus

- strengthen the tomato plants as soon as they are planted: by watering regularly (every 15 days or so) the plants (from the base!) with nettle manure which will improve the plant's natural defenses. If you don't have nettles, or don't know where to harvest them, you can buy ready-made nettle manure in many nurseries

Be careful, once the disease is established, do not water with nettle manure, it is a preventive gesture

To make a home-made nettle purin :



secateurs or scissors

fine mesh net

large container


watering can with apple


Nettle manure is used pure as a fertilizer at the foot of a plant, but it is preferable to dilute it between 10 and 20% for a treatment against insects or for a fertilizing spray on the leaves.

Good to know:

Nettle manure has a particularly nauseating odor. It is better to prepare it as far away from the house as possible!

Harvesting the nettle

To harvest nettle stems without stinging yourself, wear a pair of gloves and clothing that protects your arms. With pruning shears or scissors, cut off pieces of about 20 cm in length.

Place the stems in a net

Place them in a plastic net, like a potato or orange bag. This way, the leaves will remain inside, which will allow you to obtain a preparation in which most of the debris will be eliminated.

Let macerate in water

Fill a large plastic container with water (rain water if possible) and put the nettle fillet to soak. Let it macerate for 2 to 3 weeks.

Spreading the nettle manure

The spreading of the nettle manure is done with a watering can. This preparation is used diluted in water at 10%.

NB: It is also a good fertilizer and an excellent compost activator.

3/ If the mildew is well established, you just have to remove the diseased plants (see photos in the article) so that they do not contaminate the plants not yet affected.

Be careful, do not throw them in your compost, either burn them when possible, or put them in bags for vegetable waste


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