Boxwood with brown and dried leaves

Ideally, the evergreen boxwood has beautiful, green foliage all year round. However, if this turns brown and dries up, the plant should be examined more closely. Because it is not uncommon for these to be symptoms of a fungal disease or pest infestation. We will explain to you how you can identify the cause of the brown discoloration and how to subsequently combat it.

fungal diseases

If the leaves suddenly turn brown and dry up, this can often be traced back to a fungal disease. Which fungus causes the symptoms can usually only be determined on closer inspection. In principle, however, the following applies: As soon as there is a suspicion of a fungal disease, action should be taken immediately!

Dieback / boxwood fungus

The dreaded shoot dieback is caused by a sac fungus called Cylindrocladium buxicola. The fungus is favored by warm, humid weather and is blown onto the shoots and leaves by the wind. A disease is first noticeable in many small white-greyish spore deposits. As a result, orange to brown spots appear on the upper side of the leaf, which grow larger and finally grow together to form a large area. If the fungus is not combated, the fungus will continue to spread. The leaves fall off and the shoots gradually die off. It is therefore advisable to act immediately when symptoms appear:

• Prune boxwood immediately and vigorously
• Cut back into the healthy tissue
• Dispose of cut shoots in household waste
• Rake up and discard fallen leaves
• remove the top layer of soil

boxwood wilt

The box tree wilt can be traced back to the sac fungus Fusarium buxicola, which mainly affects old box trees. A disease is first noticeable on the leaves, because they become wilted and leathery soft. Dark brown spore deposits can also be seen on the leaves, mostly as small dots. If the fungus continues to spread unhindered, it can also affect the shoots. However, the shoots are usually affected relatively late. If the plant falls ill with boxwood wilt, it is best to proceed as with the boxwood fungus:

• strong pruning into the healthy tissue
• Dispose of fallen and cut leaves in the household waste
• remove the top layer of soil

boxwood canker

Boxwood canker occurs mainly in weakened plants. However, it can also be favored by care errors. Because both drought stress and waterlogging as well as a lack of nutrients and an incorrect pH value promote the occurrence of boxwood canker. If the plant falls ill with boxwood canker, this is first noticeable by twisted and attached leaves. The leaves first turn yellow, later brown and finally fall off. Pink pustules may also appear on the leaves. If the boxwood canker is not treated, the hind tears open or even detaches itself from the wood. Entire branches can also dry out. Again, it is advisable to act quickly:

• Prune the boxwood vigorously
• to the healthy tissue
• Discard diseased plant parts
• also the fall foliage!

boxwood rust

Another dangerous fungus for boxwood is the rust fungus Puccinia buxi. This primarily affects older and weakened box trees and settles on their leaves in spring. The fungus penetrates further into the tissue, so that rusty-brown spore deposits become noticeable on the leaves in autumn. Boxwood rust should also be combated immediately:

• cut off affected shoots
• dispose of in household waste
• Use fungicide if infestation is severe

pests

Brown and dry leaves are not always a sign of fungal diseases, because the symptoms can also occur with a pest infestation. However, the unwanted pests can usually be fought relatively easily and, above all, reliably.

boxwood spider mite

The boxwood spider mite prefers a dry and warm climate, which is why an infestation usually occurs in summer. This can initially be recognized by fine, yellowish stripes and spots on the leaves. The foliage then turns bronze to brown and dries up. If the infestation is not combated, it will ultimately lead to leaf drop. However, boxwood spider mites can usually be effectively combated as follows:

• use oily agents
• this destroys the eggs
• Spider mite remedy in spring
• natural enemies: predatory mites

boxwood midge

In the case of an infestation with the boxwood gall midge, the symptoms are about the same as in the case of an infestation with the boxwood spider mite. The spots that appear are also yellowish, but larger and less sharp. In addition, the underside of the leaf is swollen like bubbles. If only individual leaves are affected, this is usually not a cause for concern. The situation is different, however, if the infestation spreads. Because this can lead to massive leaf loss and thus to the weakening of the plant. In the case of an infestation with the boxwood gall midge, the best way to proceed is as follows:

• remove individual leaves in spring
• before the larvae hatch
• Cut back the boxwood if the infestation is severe

harmless causes

Brown and dry leaves are not always a cause for concern. Because it is not uncommon for these to be natural reactions of the plant or care errors. Intervention is not always necessary in these cases, because the brown leaves usually turn green again by themselves.

Not enough water

Adequate water supply is one of the basic requirements for healthy growth of the boxwood. However, if the plant is in a particularly bright location and it has grown too densely, water absorption can be affected. Because in this case, the rain can not only penetrate the dense foliage into the ground. The boxwood does not absorb enough water, which in turn turns the leaves brown. However, this can usually be remedied with the right watering behavior:

• water regularly
• even in the rain!
• Special fertilizer in spring and summer
• this strengthens the boxwood

sunburn

It is not uncommon for entire sections of the bush to turn brown in the same direction. The south to south-east side is usually affected. If there are no other symptoms, this can usually be traced back to sunburn. Especially when the leaves are covered with hoarfrost and suddenly get a lot of sun.

cold

If the boxwood gets yellowish or brownish leaves in winter, this is usually not a cause for concern. Because this is a natural reaction of the plant, which wants to protect itself from the low temperatures. In this case, there is nothing to do because the leaves will turn green again by themselves.

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