Sooty mold is a disease caused by a group of fungi that rages on plants, especially on all citrus and lemon trees, from spring onwards, after an attack of biting-sucking insects (red spiders, aphids, mealy bugs….). These insects feed on the sap of the plants and excrete a sweet honeydew on which sooty mold develops.
The foliage is then covered with a black and sticky film that considerably hinders photosynthesis. The plant thus affected produces less sap and can no longer properly meet its own needs. It weakens.
Many citrus trees (lemon trees, orange trees, Buddha’s hand…) are plants particularly sensitive to fumagine.
A natural treatment against fumagine
To eliminate sooty mold on a lemon or orange tree in a pot, it is necessary to put an end to the infernal cycle imposed on the plant by the insects. We will therefore act in several steps.
First of all, by eliminating a maximum of aphids or scale insects that you can crush with your fingers (wearing gloves for the most sensitive gardeners). On large shrubs, the power of a water jet is effective in removing aphids, especially on the back of the leaves. This operation should be carried out regularly. The adults resist but their larvae, detached and deprived of food, die.
Then, by cleaning the foliage and the trunk of the trees with a sponge or a cloth soaked in water and black soap.
Finally, by using a natural insecticide or by making one. Pour into a liter of warm water a teaspoon of rapeseed oil, one of alcohol at 70 ° C and a last one of black soap. Shake and spray on and under the leaves. Repeat the operation one hour later and then once a week during the summer. Protect the surface of the pot with boards or a tarpaulin to prevent the mixture from penetrating the soil.