The yew, also called Taxus baccata, is easy to care for. Only rarely does the plant suffer from diseases or fungal infestation. The evergreen plant has soft needles. These occasionally turn yellow, especially in young plants, but this is not a disease. Below you will find out what you can do if the yew gets yellow needles.
Yellow needles on the yew
Diseases are not the cause of yellow yew needles. The discoloration can
- unfavorable location
- pest infestation
- mushrooms
- nutrient deficiency
- normal aging
be evoked. Mostly young plants are affected, which were planted only a year ago. They are not properly rooted in the ground yet. The plant begins to sprout and needs a lot of energy, water and nutrients. The plants cannot yet optimally absorb these important substances from the soil. They react with discolored needles and with needle dropping. The plants usually turn yellow on the trunk, from the inside out.
tip: Your yew hedge will turn green again next year, provided the causes of the discoloration are eliminated. Yellowing is not a serious problem, but you should take steps to help your plants.
Unfavorable location
Yews are robust and can tolerate any location. Shade and direct sunlight are no problem for older plants. However, young plants do not cope well with strong sunlight and turn yellow. This is also the case in winter with the winter sun. You should choose a location that is not too sunny. There should be enough shade around noon. The location should be as wind-protected as possible.
Help for young plants
If the yew is still young and turning yellow, you can help it by giving it more water, even if yews don't really like waterlogging. The soil can be enriched with humus to make it more permeable and retain moisture better. You promote soil life with a combination of a bacterial mixture (root stimulator) and organic soil fertilizer. This allows new radicles to form quickly. The plant can then absorb the water and nutrients better. In addition, you can remove the yellow needles by hand or slightly cut back Taxus baccata.
pest infestation
The pests that cause problems for your yew include the vine weevil, the scale insect and the bud gall mite. They become a problem with young plants, while an older yew hedge is largely robust against such pests.
tip: If you ensure biodiversity, you can largely prevent infestation with pests. You should look out for a cocktail of worms, soil bacteria and mold that ensure a biological balance and produce valuable humus.
Vine weevil and larvae
The vine weevil is also known as the yew beetle. The larvae are white maggots and can nibble on the roots. When the yew develops yellow needles, you should dig up the plants and check for an infestation of vine weevil larvae. The beetles are active from May. They are 9 to 11 millimeters in size and remain hidden during the day. However, you can tell if there is a beetle infestation if the soil around the trunk is a little disturbed. Fighting the larvae and beetles with insecticides is hardly possible. Biological control is better.
ridged weevil
Control with nematodes
Nematodes are also available to individuals and are effective pest control measures. They offer a number of advantages:
- attack the larvae from the inside and eat them up
- multiply quickly
- are completely harmless
The nematodes love a moist soil, which is why you should pay attention to sufficient watering. The biological control of the vine weevil and its larvae can also be carried out with other beneficial insects:
- birds such as chickens
- soil bacteria
- molds
scale insects
The scale insects are active on the yew needles and cause them to turn yellow. They are often difficult to identify. A scale insect infestation is likely if you see ants on the yew tree. The ants feed on the honeydew produced by the scale insects. In summer, the scale insects form waxy egg sacs on the needles and branches of the yew trees. They suck the sap and can become a serious threat as they multiply rapidly. It is therefore important that the scale insects are thoroughly combated. A single louse can produce up to 1,000 offspring. Control with insecticides is also not effective for scale insects.
biological control
You can fight scale insects efficiently in a biological way. This can be done in a variety of ways:
- Cut off affected branches
- Interruption of the ant trails
- Use of parasitic wasps
- Use of the ladybird Exochomus quadripustulatis
Ladybugs are also used in nurseries. They will also stay in one place for several years if the scale insect population is persistent. They can be used together with the parasitic wasps. Ichneumon wasps can easily penetrate the scale insect’s strong shell.
bud gall mite
The bud gall mite affects the leaf and flower buds of the yew tree. An infestation can be recognized by the fact that the leaf buds are thickened to about 6 to 8 millimeters in size and sprout poorly. The scales of the flower buds are bent apart. Taxus baccata needles turn yellow. Later the growth is stunted and reminiscent of barbed wire. You fight the mites by removing the affected shoots. In addition, you can use a pesticide.
fungus
Yew needles can also turn yellow due to fungal infestation. You should suspect a fungal infestation if you don't see any signs of pest damage. Fungal infestation can have various causes:
- bad care
- too densely planted yew hedge
- humid weather
- waterlogging
Fungi are difficult to fight, often you can no longer help the plant. You should cut off all affected parts of the plant. You should loosen the soil and create drainage. You can also counteract fungal infestation by adding fertilizer.
notice: Never dispose of the infested parts of the plant in the compost, otherwise the fungi can spread quickly.
Taxus cuspidata, Japanese yew
nutrient deficiency
If your yew needles turn yellow, you should also consider a nutrient deficiency. You should use a nitrogenous fertilizer. While fertilizers containing nitrogen are possible until mid-August, you can also apply fertilizers containing potassium and phosphorus from mid-August.