Cultivating a lemon tree is not complicated. However, various factors must be taken into account in order to optimally care for the plants from the rue family. Terraces and conservatories can be transformed into Mediterranean oases with citrus plants. A large number of passionate gardeners have discovered their passion for the exotic plants. It is all the more annoying when, despite painstaking care, you discover conspicuous features such as brown discoloration and black spots on the leaves.
Black discoloration
The cause of the black discoloration
A black coating on the leaves of the lemon tree is not due to a mistake in care or a wrong location. Soot fungi are responsible for the conspicuous, dark discoloration. And the fungal pathogen does not come alone. Coating and stains are an unwelcome side effect of lice and mites. The sugary excretions of these insects, the honeydew, is an ideal basis for the pathogen. The fungus is also known among gardeners under the names black spot, sooty soreness and black spot. Indoor and garden plants are equally affected by the disease.
The star-shaped spots that cover the foliage of the plants are characteristic of the fungal pathogen. Within a short time, the sooty fungus spreads over a large area on the affected leaves. The photosynthesis performance of the lemon trees is impaired.
The plant is no longer able to carry out the vital metabolism unhindered. If left untreated, the disease can lead to the death of the affected plants in the advanced stage and spread massively to other plants in the garden or room. In contrast to other fungal pathogens, sooty mold only affects the outer plant tissue.
The symptoms of sore throat itself are easy to eliminate. For example, by removing the affected parts of the plant or by using a special fungicide from specialist retailers. Control should not be limited to the sooty fungus alone, but should be directly related to the elimination of the pests. As long as the pathogen finds an ideal breeding ground on the plants, the black discoloration on the leaves will not go away and will keep coming back. In order to take the right measures against black spot disease and the unwelcome lodgers, you should first determine the type of pest.
fight pests
aphids
Get rid of aphids from the citrus tree
With over 3000 different species worldwide, Aphidoidea are among the world's most well-known pest species. The variety of colors of the small crawlers varies, but not the way they eat. The insects penetrate the leathery surface of the lemon tree leaves with their small mouthparts. In this way, the voracious contemporaries deprive the plant of its lifeblood.
The following signs are typical signs of aphids:
- sticky plant parts
- brown discoloration on the foliage
- leaves wither
The sticky excretion of the insects on the lemon tree is almost always the first indication that the gardener notices when there is an infestation with aphids. In many cases, the culprits are on the shoots and on the underside of the leaves of the lemon trees. These simple "home remedies" have proven effective in combating aphids.
- wipe the underside of the leaf with a rag
- pour with a broth of nettles or field horsetail
- Spray diluted nettle broth on the affected areas
- Deploy pheromone traps
Animal predators, such as lacewing larvae and ladybirds, help in their own way to get rid of the pests. A natural environment with numerous hiding places is gratefully accepted by the little helpers. For a faster result, eggs and adult insects can be bought directly from specialist retailers. This is especially recommended for outdoor plants. Aphids rarely come alone. If there is a strong ant population, these insects should also be combated.
Mealybugs and scale insects
Get rid of mealybugs and scale insects
Brown spots on lemon tree leaves can be an indication of scale insects. The next generation of defective insects in the form of eggs and larvae slumbers under the hard shell of the female specimens. Insecticides do not work on scale insects, the animals quickly develop a hereditary resistance to the aggressive agents. Despite this fact, one is not powerless against an infestation of scale insects.
- Wipe leaves and insects with alcohol
- Remove heavily infested parts of the plant
- regularly spray the citrus tree with nettle decoction
A common mistake: scraping away the shells of the scale insects with your fingernail or the tip of a knife. With this measure, the eggs of the insects are distributed over a large area over the plant, which makes it difficult for the animals to get rid of them.
Mealybugs are related to scale insects. To protect themselves, these insects cover themselves with a mealy-looking layer of wax. The pests can easily be picked off the shoots and leaves by hand. Lice are sensitive to high humidity. While fighting the pests, it is advisable to move the entire plant to a warm spot and spray it with a water sprayer several times a day.
spider mites
Aphids and the like are not the only pests whose legacy promotes sooty mold. The small crawlers prefer to infest citrus trees in winter quarters. Silvery shimmering webs and a sticky plant surface are typical signs of spider mites.
- avoid the immediate vicinity of active heating sources
- Do not let the citrus tree dry out completely
- increase humidity
A small lemon tree can be freed from insects with a trick. The following materials are required for this.
- wooden sticks
- water atomizer
- Transparent film
A small greenhouse is built around the plant with the sticks and the foil. The water cannot evaporate under this construction and forms dew on the leaves and shoots. Citrus trees take no damage from this method. Completely in contrast to the spider mites.
The population of pests is weakened and can be completely eliminated with the help of pheromone traps and wiping the shoots. Washing down with a strong jet of water in the bath or shower has also proven effective. If necessary, the measure should be repeated on the lemon tree.
preventive measures
With the right technique and patience, sooty mold and pests can be removed from the lemon tree. However, there is a way to minimize the risk of an infestation in advance. Healthy lemon trees are rarely plagued by diseases and harmful insects.
- water and fertilize properly
- choose a bright location
- Permanently increase humidity by placing water containers
- Avoid being near heaters in winter quarters
- Check leaves and shoots regularly
The last point in particular can effectively help to notice noticeable changes in the plant in good time and to react to them. In this way you prevent the sore throat from spreading unhindered on the Mediterranean citrus plants.