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Olive trees are quite robust and healthy trees. However, they are not resistant to pathogens and pests. They mainly occur when the care is not right and the keeping conditions are not optimal. Signs of an infestation can include brown leaf tips or leaf fall. They, in turn, can be the result of a lack of light, too much moisture, an oversupply or undersupply of fertilizer or incorrect hibernation. Potted plants are particularly at risk.
problems
The most common problems with olive trees
If the olive tree loses leaves, especially in winter or after moving to winter quarters, this is a completely natural process and nothing to worry about. However, if the leaves are falling more often, this can also indicate a fungal or pest infestation. Fungi, bacteria or pests can settle and multiply particularly easily on weakened plants.
A possible infestation can manifest itself in different ways, e.g. in the form of leaf spots, brown leaf tips, yellowish leaf discoloration or leaf loss. So that fungal diseases and pests have no chance, you should create optimal conditions to strengthen the plants and keep them healthy. If an infestation does occur, it is important to recognize it as early as possible in order to know what is wrong with the olive tree and to be able to take countermeasures as quickly as possible.
causes
nutrient deficiency
The foliage provides information about the state of health of the olive tree. Excessive leaf discoloration, turning yellow, drying up at the edges, and drooping is often a sign of nitrogen deficiency. Wilting leaf edges and brown leaf tips can also indicate that too much has been fertilized.
Countermeasures:
Whether, how much and which fertilizer this tree needs depends primarily on the substrate in which it is growing. In this country, the olive tree is usually kept in a bucket due to its limited winter hardiness. The nutrients are used up relatively quickly here, so regular fertilization is essential. Nevertheless, a certain amount of sensitivity is required when fertilizing, because over-fertilizing can cause considerable damage to the plant.
- in case of over-fertilization, a quick change of the substrate is recommended
- if there is a lack of nitrogen, transplant the olive tree into fresh substrate in the coming spring
- or apply a suitable fertilizer
- use a larger planter if necessary
- Commercial citrus fertilizers are well suited
- Give fertilizer with the irrigation water
Basically, olive trees kept in pots should be fertilized every 2 - 3 weeks from March to September. Planted specimens in milder regions can also be supplied with an organic fertilizer such as compost or horn shavings. In nutrient-rich garden soils, additional fertilization is often not required.
lack of light
Light or sun is an important resource for this plant because it needs it for vital photosynthesis. The more she gets of it, the better, because the olive tree is a true sun worshiper and accordingly loves full sun. However, it is often the case that there is not enough light and the olive tree loses its foliage. This phenomenon can occur both in summer and in winter. A lack of light is particularly threatening in the winter months. As a result, some of the foliage may turn yellow and eventually fall off.
remedy:
Outdoors, it's usually relatively easy to move the plant to a sunnier spot if it's in a container. Supportive taller plants or other shady factors should be avoided or, if possible, removed. This applies to both indoors and outdoors. If the lack of light is severe, additional plant lamps can be used for the duration of the winter.
Too much wet
In their natural habitat, olive trees tend to be dry. Their roots go deep into the ground and are heavily branched, so that they can also absorb moisture from deeper soil layers in order not to dry out. Specimens in the bucket are often watered over, which can lead to waterlogging in the root area and thus to rot.
If the rot is already advanced, it can spread to the trunk, the inside of the trunk decomposes more and more, the plant is then often beyond saving. The whole thing is favored by constant precipitation, missing or insufficient drainage and thus poor water drainage as well as plant pots without drainage holes. The olive tree is not used to this state of permanent moisture, so it reacts with brown and bent leaves, withered leaf tips and leaf loss. In addition, this increases the susceptibility of this plant to diseases and pests.
Countermeasures:
- Repot affected plants in the bucket as soon as possible
- repot into a fresh and drier substrate
- equip new pot with a drainage layer
- use a loose and well-drained substrate
- mix in sand for better permeability
- affects potted plants as well as specimens planted out in the garden
- Place the olive tree in a place that is protected from rain and very bright
- check the moisture content of the soil before each watering
A moisture meter can be helpful to determine the moisture content of the soil, but your fingers will also work. So that excess water can drain off easily at all times and there is good ventilation, it can make sense to place the pot on feet off the ground.
Tip: If the leaves turn brown, curl up or fall off, this can also be a sign of drought damage or lack of water. Even if olive trees cope very well with drought, they still need sufficient water, especially in buckets.
fungal diseases
bacterial infection
A fungal infestation can also be responsible for yellow or brown leaf discoloration, spots and ultimately leaf loss. This, in turn, occurs mainly in connection with too much moisture. Eye spot disease, leaf spot disease and a sooty disease caused by the fungus Fumago vagans are particularly worth mentioning here.
leaf spot disease
Leaf spot disease, caused by a fungus called Mycocentrospora cladosporioides, is mostly seen on the undersides of leaves. They are yellowish with black spots. As a rule, this disease comes from overwintering, for example when the plant sweats under winter protection.
Measures to combat:
If such a fungal infestation is found, better ventilation should be provided. If the shoot tips are still intact, it is usually sufficient to shake the plant vigorously so that all affected leaves fall off. The plant can then be treated with a copper-based broad spectrum fungicide. Control with biological means is not possible. If the infestation is already advanced, affected parts of the plant should be cut off generously and disposed of.
eyespot disease
In contrast to the leaf spot disease, the fungus Spilocaea oleagina, which is responsible for the eye spot disease, attacks the upper sides of the leaves. An infestation occurs above all with continuous rain or overhead watering, i.e. continuous moisture. The tips of the leaves show lighter spots on the inside and darker, brown or silvery-grey spots on the outside. The plant eventually loses its leaves and the shoots die off.
Measures to combat:
First, you remove both infested leaves and those that have already fallen and dispose of them in the household waste. Then treat the olive tree with a suitable fungicide according to the manufacturer's instructions. Since the young leaves in particular are very susceptible to this fungus, it is advisable to treat the plant preventively with a copper-based fungicide the following year. The best time for appropriate spraying is in the spring, although they must be repeated after about 10 - 14 days.
fungus
Fumago vagans
An infestation with this fungus is indicated by a black, sooty coating on the leaves and bark of the olive tree. Causes can be a too warm hibernation with high humidity but also the result of an infestation with wool or scale insects. If it is due to hibernation, the appropriate protection should be removed and the plant should be well ventilated. Only affected leaves can then be wiped off with soapy water. If, on the other hand, a pest infestation is the cause, this must first be eliminated.
Tip: This fungus usually has no effect on the health of the olive tree. Nevertheless, affected leaves should be treated accordingly.
Wrong wintering
In winter, it often happens that the olive tree loses leaves, brown leaf tips appear or leaves turn yellow or brown. As long as no serious mistakes are made during the winter, there is no drama when the tree loses leaves. However, if the leaf loss is massive, this can indicate frost damage. Sudden frosts are not uncommon in autumn and spring. If the olive tree stands outside in an unprotected place without adequate winter protection, it loses its leaves. In extreme frosts, the roots can also be damaged. The olive tree tolerates slight minus degrees.
If it loses more foliage, this may be due to the fact that it has hibernated in a dark room for too long and too cool. Not only falling leaves, but also yellow and brown leaves that do not necessarily fall off can be a reaction to cold temperatures or frost damage. In addition, already rising sap streams can lead to cracks in the trunk and shoots due to strong temperature fluctuations. Ice-cold airing in winter, to which the olive tree is exposed without protection, can also result in leaf discoloration. If necessary, the leaves can already be damaged if they come into contact with an ice-cold window pane. On the other hand, brown leaf tips can be an indication of insufficient humidity.
counteract frost damage
- in case of damage caused by ventilation, move the plant
- Protect the olive tree with translucent foil during ventilation
- Bring trees in buckets indoors before the first frost
- not before the ice saints go outside again
- Winter quarters neither too cold nor too warm
- Winter temperatures of 5 degrees are optimal
- then the plant can get by with a little less light
- vegetation sets in from a temperature of 10 degrees
- then it must be much brighter
- in winters colder than minus 5 degrees, hibernation exclusively in the house
- young plants generally overwinter frost-free
- planted specimens with better winter protection
- protect above-ground plant parts and root area
In order to protect the trunk and branches, sufficient frost protection must also be ensured in the spring. When wintering outdoors in particularly mild locations, you should ensure a sheltered location, ideally near the house or in front of a protective object. A translucent, breathable and water-repellent fleece should be used as winter protection and the plant should be protected from direct winter sun. Cracks in the trunk are best wrapped with straw, fleece or something similar. On frost-free days, it also needs to be watered occasionally.
pests
Pest infestation occurs mainly in winter, although it rarely occurs outdoors. Again, the causes are mainly due to improper care. If the plant loses leaves or shows symptoms such as curled, brown or wilted leaves, this can indicate an infestation with scale or mealybugs.
Scale and Mealybugs love warmth and appear mainly during a warm hibernation. These pests prefer to sit on the undersides of the leaves and then quickly spread over the entire plant. In addition, a scale insect infestation can also result in various fungal diseases.
Combat is usually difficult. Affected plants should first be isolated and then treated with a systemic agent. Older specimens can be exposed to light frost for a certain period of time, for example overnight, to combat the pest. As a preventive measure, you should ensure a cool hibernation at a maximum of 10 degrees.