La fumaggine is a disease that manifests itself with the appearance of black and sooty areas on stems, leaves and fruits and affects many plant species. It is caused by the action of different saprophytic fungi, including Cladosporium, Torula, Alternaria, Capnodium, Aureobasidium, Ceratocarpia depending on the plant species affected. There are three plants most interested in citrus fruits, the olive, melo but also theoleander, ficus and pink. In reality, the fungi that cause smokiness do not attack the plant species directly. The fungus, in fact, remains on the surface of the leaves, feeding exclusively on sticky and sugary substances, honeydew, produced by pests. Therefore, smoking is almost always a secondary disease associated with an attack by others parasites. Honeydew, in fact, can attract other insects such as ants as well as the fungi that cause smokiness. In the next paragraphs, we will analyze in greater detail the fumaggine, what it entails and how to avoid it.
Causes of smoking
The main cause of the appearance of fumaggine, as specified above, is due to the presence of phytophagous insects such as aphids and scale insects. Therefore, the disease occurs in the period between spring and autumn, the period of greatest spread of pests. However, in drier climates, it can last until winter. Attacks by these pathogens leave a sugary substance on the leaf surface, the honeydew formed by the secretions of these insects. Other causes of this pathology can be conditions of poor ventilation and high humidity.
Symptoms of the smoke attack
La fumaggine it shows dark sooty structures of a brown-blackish color that can have a variable thickness starting from 1 to 3 millimeters. It is a pathology that affects the leaf surface and not the innermost layers of the tissue. Depending on the stages and severity of the disease, the consistency can be soft if the disease has just appeared or dry. The appearance of the blackish patina on the leaves it is the result of a dense interweaving of hyphae generated by the growth of the fungus. This patina hinders the photosynthesis reducing the light that reaches the leaf page. In the early stages of the disease the damage to the plant is generally of an aesthetic nature, while prolonged attacks lead to its weakening. Strong attacks of fumaggine, can cause a decay of the plant with stunted growth and loss of new shoots.
Plants most affected by fumaggine
Any plant species can be subject to the attack of such fungi from annual to perennial plants, vegetable plants, ornamental or fat plants. The disease also affects shrubs and fruit trees, causing extensive damage to crops. Among the species most affected are the citrus fruits. In particular, citrus fruits can also manifest this pathology in the autumn-winter period, on plants protected from the cold by using plastic sheets that favor the formation of condensation, thus creating a humid environment favorable to the attack of pathogenic insects and fungi. Very widespread in pot cultivation especially in greenhouses due to the humid environment and with little ventilation. Smoke is a contagious disease, it spreads rapidly through contact between infected and healthy plants, especially in humid climates. It is therefore good to sterilize gardening tools when they are used on diseased plants.
Smokiness - how to prevent it? Tips and remedies
To avoid the rooting of parasitic insects that cause honeydew and the appearance of fumaggine fungi, it is necessary to water and nutritional balance with the right irrigations and fertilizations. It is important - in the case of fruit trees, olive trees and citrus trees - to ventilate the foliage with thinning pruning. Smoke is effectively prevented by first eliminating the aphids that produce honeydew. If the smoke is not extensive it is sufficient to wash the infected parts with a strong jet of water and rubbing them with a stiff bristle brush. If the disease is extensive, mechanical intervention is recommended removal of sick parts and recourse a treatments based on copper salts or products based on Sulfur. The use of specific products against parasites helps to eliminate saprophytic fungi in a short time but is not the greenest choice. The use of resistance inductors such as FullBio oily formulation with a strong antioxidant action, Even Green a basis of Sulfur or Cupram Bio a basis of Copper they increase the resistance of plants to various types of stress.