Gardening: Watch out for diseases, it’s time to be vigilant

the essential
Downy mildew, rust, powdery mildew… This week our gardener Jérôme warns you about the diseases that can affect your plants. He will also tell you how to grow celeriac.

Heat waves, storms … the weather is particularly conducive to the development of diseases. One of the main causes are the dreaded fungi.

Once they land on a plant, they develop microscopic filaments inside their host. This slows down its development and can even lead to denaturation of the harvested parts and death of the plant.

The mushrooms

Sudden changes in temperature and humidity, and especially stormy summer days, favor the development of fungi. The same applies to excess fertilizer, watering and in greenhouses humid heat.

Some preventive measures can limit the risks:

  • Keep your plants well aerated to avoid the formation of humid micro-zones that are so many sources of infection. To do this, plant and sow broadly, carefully thinning out your seedlings in rows.
  • Avoid sprinkler watering, instead opting for foot watering or drip for widely spaced plants. And most importantly, do not water in the heat.

Don’t overwater

The main fungal diseases common to several vegetable crops are powdery mildew, powdery mildew, rust and botrytis.

Downy mildew affects potatoes and tomatoes, but also cabbage, spinach and onions. Its symptoms: Yellowish-white spots appear on the upper side of the leaf, purple-white matting on the underside – then bumpy brownish spots on the fruits or tubers.

Thank you Bordeaux porridge

Preventive sprays with field horsetail broth strengthen the plants. And Bordeaux blend sprays are effective when done early.

Rust mainly affects Liliaceae (garlic, leek, onion, asparagus). Yellow to brown pustules appear and the leaves take on a rusty appearance and then dry up. Bordeaux mixture should also be used here.


Their cultivation is often considered difficult. The easiest way is to buy seedlings in plugs from a producer.

They are planted 15 cm apart in rows 40 cm apart. They need to be buried as little as possible to allow the root ball to grow.

During their development, the outer stems are removed in favor of new ones that enlarge the root. It is necessary to mulch well and water regularly

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