When the leaves have a black deposit on the surface, much as if black soot had settled overnight, we talk about sooty mold.
A fungal disease well known to gardeners, sooty mold is not very serious in itself, but it is often the consequence of an attack by more troublesome pests such as aphids where the mealybugs.
Capnodium oleaginum or Fumago salicina is ultimately a fungus whose spores develop on the sugary honeydew of the parasites just mentioned.
Symptoms of sooty mold, black on the leaves
The main cause of the development of sooty mold is the presence of insects and pests such as aphids, whiteflies and mealybugs.
These develop a sweet and sticky honeydew that allows the fungus called sooty mold to settle and grow rapidly, thus forming a black layer on the leaves.
Rarely dangerous for the plant, sooty mold can nevertheless reduce photosynthesis when it covers all the sheets to a great thickness. This is when she comes to suffocate the leaf which ends up withering away.
On the other hand, when sooty mold only represents a few black spots, the damage is often very limited.
Preventive treatment against sooty mold
There is no real preventive treatment against sooty mold and when it does appear, it is often the time to find out.
But a few actions can limit the risk of seeing it appear.
- Make sure the plant is well nourished and well watered. A plant weakened by poor soil or a lack of water is a vulnerable plant
- Diversify the plants and flowers in your garden, this is the best way to provide them with natural protection against diseases.
Treat sooty mold
It's quite simple, spraying the leaves with Bordeaux mixture should be enough to remove sooty mold. To renew 1 or 2 times if necessary.
An effective remedy against sooty mold is also to fight against the insects that are responsible for it.
Here are the treatments:
- Treat aphids
- Fight against mealybugs
- Treat whiteflies
Once the plant has been treated and rid of these bulky pests, it is advisable to clean the foliage in order to give it every chance to fully play its role.
You will use a cloth dampened with slightly soapy water for this, then rinse with clear water.
By treating sooty mold organic way you preserve the ecosystem that surrounds the plants, especially bees which then come to forage on the flowers.
Plants affected by sooty mold
We find sooty mold on a large number of plants such as fruit trees (Apple tree, pear tree, Olivier, etc ...) of heather earth plants (rhododendron, camellia, hydrangea, etc ...), at vegetable garden (tomato, etc ...) but also ofornamental shrubs (oleander, rosebush) and D'citrus (orange tree, lemon, pomelo, bergamot, etc ...)
© Scot Nelson (Photo 1 Flickr)