Vegetables in the garden sometimes cause a lot of concern. You will have to fight against various enemies and diseases, depending on the parts of the plant: leaves, roots, flowers and stems. Know the main diseases, find out how to prevent or treat them when the plants are affected, preferably with organic remedies: nothing easier with all our practical gardening tips!
Unfortunately, there are many diseases and pests that affect plants in the ornamental garden, vegetable garden or orchard. Recognizing them to identify them will allow you to choose early treatments that are effective and environmentally friendly. Mold, rust, powdery mildew, botrytis: learn to identify diseases that can affect your vegetable garden and take care of your plants.
Anthracnose is a relatively common cryptogamic disease that affects many plants, including trees, shrubs, and vegetables. Prevention remains the best way to fight this disease.
There are many microscopic fungi responsible for anthracnose. The disease is recognized by the brown or black spots it causes on the leaves. Depending on the fungus responsible, these spots may be circular or irregular, and appear either on the edge of the leaves or along the veins. The necrotic areas extend more or less concentrically, the boundary with the healthy tissue being very clear. The leaves gradually take on a dry appearance, as if burned by the cold or the sun and end up falling prematurely. Young twigs can also wither when cancers (ie wounds) develop on the stems.
The damage is generally minor, and the disease rarely leads to the death of affected trees or shrubs: they are weakened, especially if the leaves fall significantly early and if the attacks are repeated year after year. However, in vegetable plants, wilting can be total. In any case, the harvest is threatened, because the disease also affects the fruits.
Many plants are sensitive to anthracnose: trees (apple, cherry, walnut, oak, birch, ash, maple); shrubs (vine, raspberry, black currant, currant, hydrangea, rose); vegetable plants (melons, cucumbers, tomatoes, beans, peas, spinach, strawberries).
As in most cryptogamic diseases, a rainy and mild climate is favorable for anthracnose: fungi grow optimally between 15 and 27 ° C, as soon as the humidity is sufficient. Cold, hot weather and drought interrupt the evolution of the disease. In addition, contamination occurs through the spread of spores (wind). They reach the leaves, the hollows of the bark or between the scales of the buds and germinate as soon as the climatic conditions become favorable again.
Avoid excess nitrogen fertilizers, which promote the development of fragile and therefore vulnerable shoots. Be careful not to water the leaves, as the humidity is favorable for the germination of spores. As a preventive measure, treat trees and shrubs between late winter and early spring (excluding frost). In spring and summer, regularly observe the foliage and cut the affected leaves and twigs from the beginning of the disease (then burn these contaminated wastes and disinfect the instruments well). Carefully collect the dead leaves at the foot of the affected trees and shrubs and burn them.
Botrytis (gray mold)
It is a cryptogamic disease caused by a fungus, Botrytis cinerea. Botrytis is also called gray mold or noble rot: this is the case when the development of botrytis is desired (but closely monitored), especially on vines, to obtain grapes richer in sugar and therefore able to produce wines. sweet.
Botrytis cinerea grows both on the tissue of dead plants and on living organisms and affects a large number of cultivated plants. It is especially common in tomatoes, strawberries (and all small fruits), peas, beans and certain shrubs and ornamental plants (roses, peonies, dahlias, chrysanthemums, but also carnations or lilies).
This fungus often grows on fruits (acquiring a characteristic shade of gray or brown), but can also affect flowers (wilting), leaves (brown spots, then leaf destruction), roots (rot), stems and branches (drying) or seedlings. The damage is variable: we can see the wilting of only a few leaves or flowers, but when the conditions are particularly favorable, the attack can compromise the harvest or can greatly affect the aesthetics of the plant.
Gray mold appreciates moderate heat (development is optimal between 18 and 20 ° C) and especially humidity (rainy periods, humid atmosphere in the greenhouse). Poor ventilation is also a favorable factor (cultivation in limited spaces, dense vegetation).
Prevention is especially important: of course, no one controls the weather conditions, but it is possible to reduce the risk of attack by ensuring good ventilation around the installation and sensitive organs. In terms of treatment, fungicides can be used, although gray mold strains tend to become resistant to frequently used chemicals.
It is a cryptogamic disease caused by various fungi that affect many plants, both in the garden and in the layers of vegetables. Withered stems, yellow spots on leaves, rotten roots are the first symptoms.) Depending on the fungus in question and the plant species affected, the severity of the disease is variable.
Fungi develop a mycelium in the soil and contaminate plants through roots. Conductive vessels may be affected. Some strains also produce mycotoxins. Climatic and agronomic conditions (unbalanced soil, lack of crop rotation) influence the development of the disease. Although each fungal species evolves differently, warm (25 ° C +) and humid conditions favor their appearance.
If wilting caused by fusariosis is best known in cereal crops such as wheat, and perennial or annual ornamental plants (dahlias, freesias, herbs, daisies, carnations, sweet peas, etc.), vegetables (asparagus, eggplant, beans, melons , peas, potatoes, tomatoes), fruit trees and lawn can be affected by these fungi and show more or less comparable symptoms.
There is no treatment for the affected plants. In case of attack, the only possible actions are to stop the spread of the disease: uproot the affected subjects, collect them with a leaf vacuum cleaner ( here is a comparative list ) burn them, remove the soil around the roots and stop growing sensitive plants or varieties. there.
As a precautionary measure, mulch the garden soil (this avoids the spread of pathogens), respect the rotation of vegetables, grow healthy plants and seeds, hardy varieties and use healthy soil when planting. Finally, rebalance and lighten your soil by adding baked compost.
It is a fungal disease caused by a fungus found in the soil: Plasmodiophora brassicae.
When a plant that carries the fungus dies, it releases pathogenic spores into the soil. The spores can survive for many years waiting to find the roots of the host plants.
The hernia fungus attacks plants from the cultivated Brassicaceae (Cruciferae) family, such as cabbage (cabbage, green cabbage, Brussels sprouts, cauliflower, Chinese cabbage), turnips, radishes, route. The first signs of infestation appear on the aerial parts of the plant: first the leaves wither. It is observed especially on hot days, the coolness of the night restoring the affected young plants. Then yellow discoloration may occur.
Unfortunately, when these symptoms are visible on the leaves, it means that the fungus is already present at the roots: first, some solid swellings form. Then the roots grow. Eventually, they become black and rotten, giving off an unpleasant odor. Cabbage hernia disrupts the growth of the infected plant and can cause its death.
The pathogenic fungus grows mainly in acidic soil. Temperatures between 19 and 25 ° C combined with high soil moisture are also favorable factors for the development of the disease. The attacks can be seen throughout the growing season. Propagation vectors are numerous: earth, water, shoes, tools, etc.
Improves soil drainage if necessary: excess water promotes the spread of the disease. Make calcareous changes if the soil has a pH below 6. Extend rotations. Clean tools to avoid contaminating healthy soil. In case of infestation, the only solution is to remove and burn the affected plants or let them decompose away from the vegetable garden.