Boxwood is an evergreen shrub that is very popular in our gardens and throughout southern and central Europe. These beautiful shrubs are usually planted as hedges or as individual eye-catchers. Since the boxwood can be easily cut into a ball, cone or cube shape, it is well suited to modern gardens where minimalism and geometry prevail. It can also be grown in a pot. Just like other plants, boxwood is subject to diseases and pests that are usually easy to diagnose. We give you an overview of the most common pathogens that may threaten the boxwood.
Possible causes of discoloration
The leaves should generally remain green through winter and summer.The undemanding shrubHowever, it can sometimes give its owners an unpleasant surprise - the leaves begin to change color, turn yellow, fall off, and over time not only the leaves but also the branches dry out.
The reason for this phenomenon may lie in one of the following factors or their combination:
– too much sunshine
– incorrect watering
– Nutrient deficiency
– low temperatures
– Boxwood diseases
– Pest infestation
The boxwoodgrows best in partial shade. If you plant a shrub in a sunny location, it will quickly lose its green color. Therefore, avoid locations where the plant is under the sun all day.
Direct sunlight is especially dangerous for perennials in spring and even at the end of winter, when there is a strong warming after the cold and gloomy winter days. During this time the boxwood begins to awaken to new life and is very sensitive to the blazing sun.
Yellow leaves can also be a signLack of nutrientspoint out. This can happen, for example, if you forget to fertilize regularly from April to autumn.
Some types of boxwood are sensitive to low temperatures and severe frosts. A long, frosty winter causes the leaves of the boxwood to turn yellow and dry out. A windy location is also not recommended for the boxwood. ThePotassium-concentrated fertilizershould be used in the fall. It promotes the woodiness of the shoots and improves the resilience of the boxwood.
Fungal diseases in boxwood
Cylindrocladium buxicolaandI boxed a voluteare both fungi that attack both the branches and leaves of the evergreen shrub.
These mushrooms love warm, humid weather, which keeps the plant constantly moist. Therefore, you should pay particular attention to shrubs that are in the shade. A fungal infection usually begins with Cylindrocladium and can then be followed by a secondary infection with Volutella. Both types of fungi cause dark brown spots and leaves and are therefore sometimes used as synonyms.
Boxwood shoot dieback or boxwood fungus (Cylindrocladium buxicola)begins with black spots forming on the leaves. After a few days, the affected leaves fall in large quantities and black streaks appear on young branches.
Boxwood cancer(Volutella buxi)
Volutella Buxiis a pathogen that causes shoots and leaves to die in spring. The disease begins with the brown discoloration of the leaves, which then wilt but remain attached to the plant, at least temporarily. Pink or rust-colored spots appear on the underside of affected leaves due to the spread of fungal spores. In the event of an attack of illness, immediately remove the affected parts.
Phytophthora-Welkeatbook
Phytophthorais the name of the fungal disease caused byPhytophthora cinnamomiis caused. It is manifested by sudden wilting, yellowing and browning and then the death of young shoots. Diseased plants have poor growth. If the bush is removed from the ground and the roots look rotten and weak, you can be sure that you are dealing with this fungus. The development of Phytophthora is promoted by a temperature of 20-25°C and frequent moistening of the plants.
Powdery mildew looks like white dust
Powdery mildewjoinsa large group of plantson, mostly in roses, but can also be transferred to boxwood. The disease is caused by the fungus from the familyErysiphaceaecaused. As the fungi develop, a characteristic mealy, white coating forms on the leaves and other parts of the plant. Over time, the mycelium darkens and produces spherical dark brown or black spores. The development of the disease is favored by frequent rain or temperatures below 20°C. The disease threatens shrubs during the growing season, but is more common in spring and at the end of summer and beginning of autumn.
Macrophoma
The fungal infestationMacrophoma Candolleiis another disease that threatens the boxwood. Black fungal spores are visible on the leaf surface and cover the entire leaf surface. Over time, the leaves and shoots die. The disease is transmitted through water, for example when it rains.
Animal pathogens
Boxwood is often subject to aphid attacks. If you have small lice on yourNotice bushes, these must be removed as quickly as possible. The easiest way is to rinse the bush with a strong jet of water from the garden hose. In this way the aphids are removed mechanically. However, for better results and future prevention, it is worth using home remedies such as a solution of garlic, onions or potatoes. These are cut into pieces and placed in a bowl of lukewarm water. After 24 hours of soaking, you should pour the solution into a bottle with a spray attachment. The pest control product is ready for use.
Psylla Buxi –Buchsbaumblattfloh
The boxwood psyllid is a common wingworm that feeds on plant juices, and the juices from fresh boxwood leaves are particularly tasty for it. The larvae overwinter under the bud scales, from which young leaves develop in spring. After a few weeks, the larvae transform into adult insects. They are greenish-yellow, about 4-5 mm in size. In July, boxwood fleas lay their eggs on the leaves of the boxwood.
Symptoms include:
– Waxy white threads like clouds on young leaves.
– After shaking the bush, white pollen falls.
– The curling of young leaves, which resemble a head of cabbage, is typical.
– Young deformed leaves are covered with sticky secretion secreted by larvae.
– In July, adult, winged insects appear near young boxwood shoots.
Boxwood borer(Cydalimaperspectalis)
Cydalima perspectalis, best known as the boxwood caterpillar, is native to East Asia. The insect probably first arrived in Germany in the mid-2000s via an Asian shipment of Buxus sempervirens plants. However, it is already active in the Netherlands, France, Great Britain, Luxembourg, Denmark, Poland, Austria, Italy and Romania.
The damage this hungry pest causes to boxwood can be devastating. You will quickly recognize the arrival of this pest in your garden. No other garden pest will leave such unusual and obvious marks on your beautiful shrubs. What is striking is that only the soft parts of the leaves are eaten, while the leaf veins remain untouched.
Boxwood gall midge
The susceptibility to the gall midge depends on the variety. The orange-colored insect lays its eggs on the underside of the youngest leaves in May. Two to three weeks later, the legless larvae hatch and begin to feed on the leaf tissue. In autumn, galls form on the underside of the leaves in which the larvae overwinter.
Boxwood spider mite
The tiny spider mite (0.3 mm) causes damage by sucking the sap from the Buxus leaves. The red spider mite prefers warm, dry conditions and causes tiny, yellow spots on leaves. From May onwards, treatment with a specially developed acaricide is recommended. Use a product with ingredients like tebufenpyrad and bifenazate.
Comma childless
Lepidosaphes ulmi can be found almost worldwide, mainly on fruit trees, but also on ornamental shrubs such as boxwood. The pest is 2 to 3.5 mm long, brown-gray, with a characteristic comma-like shape. The larvae hatch at the end of May - beginning of June and then attach themselves to the shoots. In the middle of summer they pupate and the adults emerge. The worm affects the health of shrubs by slowing their growth and causing shoot death.
Boxwood diseases – prevention and control
The boxwood will only be a real eye-catcher in our garden if we take care of its health. If you have any doubts about which one we are dealing with and when choosing a medicine, it is worth taking pictures of damage and symptoms. Then you should go to a good garden store along with the photo to seek advice.
Undoubtedly, the correct location and soil conditions play an important role in the condition of the shrubs. Make sure the conditions in your garden are suitable for growing boxwood. Healthy plants have increased resistance to disease and insect damage.
When damage is detected, it is necessary to react quickly to prevent the disease or pest from spreading uncontrollably. The best way to combat fungal diseases is to remove infected shoots and sometimes entire plants and use appropriate pesticides. In case of pest infestation, a suitable insecticide can also be used.
