Actually, the Kugelroninie is easy to care for. However, care errors can still occur and make the tree more susceptible to diseases and pests.
The spherical robinia (Robinia pseudoacacia 'Umbraculifera') with its bizarre growth quickly becomes the center of attention in every garden. The plants require little care and thrive quite reliably without a great deal of effort on the part of the hobby gardener. Unfortunately, the false acacia is not spared from diseases and pests. In the following you can find out which diseases and pests can occur, how you can recognize them, combat them effectively or prevent their spread through appropriate care measures.
What diseases and pests are common?
- miner moths
- scale insects
- Aphids
- Leaf spot disease
miner moths
The leaf miner is quite common on the spherical locust. The type of moth leaves behind a typical pattern of damage, which can be easily recognized by the hobby gardener. As early as spring, the moths form their typical feeding passages, which appear as wavy lines on the leaves of the globose robinia.
The larvae of leaf miners develop in the foliage of various tree species. The moths live on the sap of plants, which they get by piercing the leaves. Once the larvae have hatched, they leave intensive damage in their wake and eat all the leaves. Incidentally, they don't stop at the needles of conifers either. The leaves are changing color and leaf fall occurs as early as summer. Once the development is complete and the caterpillar has become a miner moth, it changes location. In search of a new habitat, however, the moths will not stray too far from the already infested tree and will often leave new larvae there. This closes the circle and the infestation also spreads to the surrounding plants.
What to do?
Since the leaf miner has hardly any natural predators, the infestation will hardly be minimized naturally. Only parasitic wasps are able to destroy larger populations of moths. Likewise serve the larvae and caterpillarsvarious bird species as a food source. Foliage infested by the leaf miner should be removed immediately.
» Caution: Infested plant parts do not belong in the compost and should be burned completely or disposed of with household waste.
There are a few ways to fight the leaf miner, but fighting them is generally difficult. You can treat the tree with a hard jet of water or spray it regularly with soapy water. Watering or spraying with nettle juice or tansy tea also has an effect. If insecticides are not used, it will be difficult to completely eradicate the pests. The infestation can only be contained. The hobby gardener achieves good results by setting up traps that contain parasitic wasps. The infestation is then usually completely eradicated after two years at the latest and the tree can slowly recover.
scale insects
Infestation with scale insects is also found quite frequently on the spherical locust. If you look closely at the leaves, the typical shields will be clearly visible. The pests live on the sap of the plant and cause lasting damage to the robinia. The plant is constantly being deprived of nutrients. The plants are particularly lacking in protein. The extracted plant sap is particularly sugary. The scale insect excretes so-called honeydew. This glues the leaves together. But the pests find a clever solution so that they don't stick to the viscous liquid themselves. The sticky honeydew is thrown off by the lice. It is therefore quite possible that the viscous mass can be found on window panes, garden furniture or car windows.
Tip: Honeydew promotes the colonization of sooty mold fungi, which can cause additional damage.
Scales are closely related to aphids. There are around 3,000 different plant lice. 90 species alone are native to Central Europe. The scale insect can be clearly seen on the leaves of the spherical robinia, because the pests grow to about six millimeters in size. Male scale insects can fly. The females, on the other hand, are usually completely unable to move. The pests wear a shield-like armor, which is about two millimeters thick. The shell hides the female animals. The shell, made of wax or resin, is particularly stable and can protect the pests from predators.
Hint: The eggs are laid under the shell of the scale insect and itthe larvae develop.
What to do?
Notice the scale insects on the leaves, just stripping them won't do the trick. Instead, grab a small brush, toothbrushes are particularly good and strip the shield shells from the affected leaves. You can also use vegetable oil based products. These protect the environment. The oily film reliably kills the pests, as they suffocate under the shell.
Tip: Ladybugs or earwigs are natural predators of scale insects.
Aphids
The infestation with aphids seems less tragic. The small green aphids are also easy to spot on the leaves and shoots of the globose locust, but do not cause any significant damage to the plant.
What to do?
You can treat the sapling with a hard jet of water or spray it with soapy water. Spraying with nettle broth or garlic broth has also proven effective. The use of chemical pesticides will not be necessary.
Phloespora leaf spot disease
The appearance of this fungus is indicated by the withering of the leaves. The leaves continue to form round brown spots. The shoots can also be affected.
What to do?
In autumn, ensure that the leaves are completely removed. The leaves do not belong in the compost, the fungus would continue to spread there undisturbed. Burn the leaves or put them in the trash. If the shoots are also affected, a pruning will be necessary. Prune back the entire crown generously.
» Attention: Be sure to cut back above the grafting point, otherwise the tree will lose its spherical shape.
Diseases caused by care mistakes
It is not uncommon for incorrect care to be the cause of plants wilting and dying. If the plant does not grow as usual, this can be the result of waterlogging. If the substrate is not permeable enough, the liquid cannot drain off and accumulates in the soil, which attacks the roots and causes the tree to rot. If this is noticed, the plant can be saved if it is transferred to fresh and loose substrate. Potted plants in particular are often affected by waterlogging.
Young plants should be watered sufficiently. Older plants no longer need to be watered.