If you love household plants, sooner or later – for heaven’s sake, we certainly do not want to pull it – you will come across a not very reassuring show: the leaves and branches are covered with a strange black powder, as if someone had scattered the ash or soot on plants. These are not atmospheric dirt or combustion residues, but of a very common problem, that is, the so -called smoke.
A disease with an evocative name
The smoke is called the evident similarity with the soot of the fireplaces and nothing else is only a set of dusty, dark and blackish clusters, of parasitic origin, which can affect the aerial portion of many plants, from internal and outdoors. The patina can occur in different forms: sometimes dry and hardened when the attack is dated, other times soft and sticky if the infection is recent.
The managers of this phenomenon belong to different genres of wise mushrooms – bodies that feed on dead organic matter – including Capnodium, Cladosporium, AureBasidium and Antennariella. Recent studies published on NCBI have identified the Cladosporium pseudocladosporioides As one of the main causal agents of smoke, to reconfirm the complex nature of this problem.
The triangle of smoke: mushrooms, insects and brazen
Fumanza is not born from nothing. The mushrooms do not produce direct damage, because they remain on the surface to feed exclusively of hole, a sugary substance produced by parasitic insects such as aphids, ladybugs and psille, who suck the lymph of the plants and expel the sticky droplets that fall on the underlying leaves.
The mushrooms find the ideal banquet in the hole: they settle on this sweet substance and begin to multiply, gradually forming that dark patina characteristic. Fumaggia is therefore configured as a secondary disease, because without the insects producing well, the mushrooms would not have to feed on.
Which plants are more vulnerable
Decorative leafy -leafy plants are particularly susceptible and among the favorite victims we can mention Ficus Benjamina, Philodendron, Dieffenbachia, Dracaena and Codiaeum. The succulents can also be affected, especially in winter, when they are kept in not very bright and too heated environments: the most affected genres include Crassula, Agave, Euphorbia and Aloe.
How to recognize the problem
The symptoms are unmistakable. As mentioned above, the leaves appear covered by a patina that can vary from dark gray to intense black, the thickness can go from one or two millimeters in slight cases, up to three or four millimeters in serious infestations, and the surface is dirty and sometimes sticky.
A simple test consists in passing a finger on the affected leaf: if a black track remained on the fingertip, it would almost certainly be of smoke. The patina can be removed scratching with the nail, action that will reveal the green of the underlying leaf, still intact.
The damage caused by smoke
Even if the mushrooms do not penetrate the plant fabrics, the damage can be of considerable reach. The black patina reduces the light necessary to carry out chlorophyll photosynthesis, the vital process that allows plants to produce energy: the covered leaves will not be able to breathe adequately, the breathability will be hindered and the growth will slow down.
In the most serious cases, the leaves yellow and fall: the plant will take a suffering aspect and completely lose its ornamental value. Rarely, smoke leads to the death of the vegetable, but it can seriously compromise its health if it is not treated promptly.
Prevention strategies
Preventing is always better than cure. The first rule consists in maintaining plants in optimal conditions: good lighting, correct ventilation and balanced irrigation without excesses. An too humid and little ventilated environment favors both insects and mushrooms.
Regular control of plants allows you to identify the presence of parasites early. Periodically inspected the lower page of the leaves, where aphids and ladybugs tend to hide and to the first sign of infestation, intervene manually by removing the insects with a cotton ball soaked in alcohol.
Biodiversity can be a precious ally. Even at home, to encourage the presence of natural predators such as ladybugs (easily available in specialized stores) will help control apids populations. Finally, remember to avoid the indiscriminate use of insecticides that could also eliminate useful insects.
Eliminate smoke: effective methods
When the smoke is already present, the first step consists in eliminating the insects responsible for well. Only after solving the root problem can we proceed with the cleaning of the blackened parts.
To remove the black patina, prepare a solution with a spoonful of neutral liquid soap for liter of water, spray abundantly on the affected leaves, leave to act for fifteen minutes and rinse with clean water, using a delicate but decisive jet. The operation may have to be repeated several times in the following weeks.
Potassious soft soap represents a particularly effective biological alternative: in addition to cleaning smoke, it helps to control parasitic insects. Some gardeners also successfully use mineral oil, which forms a protective film on the leaf and suffocates both mushrooms and insects.
Recent searches and future perspectives
Science continues to study this phenomenon. 2024 searches published on BMC Plant Biology have used hyperspectral imaging techniques to identify three critical wavelengths (552, 673 and 800 Nm) associated with different degrees of smoke infection, opening new perspectives for early diagnosis.
Other studies focus on biological control. Some strains of Bacillus AMYLOLIQUEFACIENS They showed promising results in inhibiting the growth of responsible mushrooms, offering a sustainable alternative to traditional chemical treatments.
