PESTS AND DISEASES OF PLANTS
Common name: fumaggine
The term fumaggine is a generic name used to indicate different types of fungi that live at the expense of the sugary secretions that can be found on the tissues of plants.These sugary substances are produced both by some insects such as aphids, that absorb with the lymph, eliminate it with their excrements (parasitic honeydew) and from an altered metabolism of the plant (physiological honeydew) .These are fungi, with a sooty appearance, which cover the surface of all the aerial parts of the plants but do not interact with they do not penetrate inside the tissues of the plant but use it only as a support, without creating even appendages to adhere in fact they grip the plant only thanks to their mucilaginous nature.
There are different genera and species of fungi that cause smokiness, and they all share only their aptitude to develop saprophytically at the expense of the sugary secretions found on the plant. Capnodium,Limacinia, Teichospora, Ceratocarpia, Coniothecium,Alternaria and numerous others.
Honeydew caused by aphids
Leaf with smoke damage
CLIMATIC CONDITIONS FAVORABLE FOR DEVELOPMENT
In the presence of honeydew, the smokiness is facilitated by a strong environmental humidity in the form of dew (and not by heavy rainfall which, on the contrary, hinders its formation) which keeps the sugary substances dissolved thus facilitating the establishment of the fungus. In addition, high temperatures are also a favorable environmental factor.
SYMPTOMS AND DAMAGES
The first symptom that can portend the future presence of smokiness are the easily recognizable sugary secretions as the surface, for example of a leaf, appears shiny and sticky to the touch. At that point it is necessary to verify the causes of their appearance and solve them.Instead, the overt presence of the smokiness manifests itself in different ways: from slight shading on the aerial parts of the plant, to blackish coatings that can be either greasy and soft or dry, crust-like, black in color, depending on their age. If observed with a magnifying glass it is noticed that this blackish mass is formed by numerous dark filaments interspersed with small nodules between which some viscous yellowish material, insects or their residues may emerge.
The damage they cause is indirect and is determined by the compact black blanket that the fumaggine forms on the plant tissues which prevents both the passage of light (thus preventing photosynthesis), and hindering the gas exchanges between the plant and the outside as the stomata are obstructed. (thus preventing breathing and perspiration). As a consequence of the infestation, the plant has a stunted development and a qualitative and quantitative decrease in production.
The smoke can be fought indirectly by eliminating the causes that can cause the honeydew.Once the cause has been eliminated, the smoke can be fought with copper-based products. insecticide a copper-based preparation.
To get rid of the black scab, you can wash the plant with mild soap and water and then rinse thoroughly to remove all the soap.