Why boxwood turns yellow

Finding that the boxwood has turned yellow is a very unpleasant discovery for any gardener. After all, it takes years to grow even a small beautiful bush. The loss of decorativeness is not the worst consequence of the yellowing of evergreen leaves. If you do not understand the causes of chlorosis in time and do not correct the situation, over time you can lose the entire plant.

Why boxwood dries and turns yellow

Indispensable in landscaping, evergreen boxwood is easy to shape into beautiful shapes, thick hedges or borders. Small hard foliage all year round pleases with bright colors. But boxwood grows extremely slowly – under the most successful conditions, its annual growth does not exceed 15 cm. Therefore, to find that the leaves have turned yellow or entire branches have dried up is a serious problem.

Correcting the situation is sometimes very simple by changing the care of boxwood. In other cases, complex procedures will be required, but the probable cause must first be established from among the many possible causes.

Unfavorable climatic factors

Boxwood is a hardy plant that can handle heat and cold, but sudden changes in weather or growing conditions can weaken the plant. Leaves are the first to respond to stress factors. If the boxwoods turn yellow, then one of these problems has arisen:

1. A sharp change in illumination after winter. The bright spring sun can burn the awakening shoots while the roots are not yet fully functional. If you do not shade the boxwood on the first sunny days, the leaf plates around the circumference of the bushes will inevitably turn yellow.
2. The leaves can acquire a red tint in the hot summer period when two factors coincide: bright midday lighting and drying of the topsoil near the stem. Boxwood is thermophilic, but at temperatures above + 35 ° C it requires partial shade or diffused lighting.
3. For central Our Country, you should choose specially bred frost-resistant varieties. The first sign of hypothermia is if the tips of the leaves turn yellow. Boxwood easily tolerates mild winters, but during severe cold snaps, the entire part that is not covered with snow can freeze.

Improper care

Not only natural factors affect the fact that boxwood leaves turn yellow. Sometimes care does not meet the needs of the plant, to which the bushes react by changing color.

The most common causes of yellowing boxwood:

1. Insufficient hydration. Boxwood is not picky about watering, but prolonged drying of the topsoil is contraindicated for it. It often happens that the boxwood turned yellow after pruning, if the mandatory watering after the procedure is missed.
2. Dry air. With insufficient humidity, it is useful to spray young bushes from a spray bottle. This will stop the yellowing. It is useful to combine the procedure with foliar top dressing.
3. Excess moisture. Stagnation of water in the soil is unacceptable when growing boxwood. Systematic overflow provokes root rot. At the same time, the leaf plates turn yellow gradually, signs of general wilting are observed.
4. Lack of nutrition. The lack of microelements can be manifested by the fact that the tips of the leaves or the interveinal space have turned yellow. Over time, the color of the entire green part changes, and the plant may die. Usually yellowing is due to a lack of phosphorus or potassium.
5. If boxwood is yellow mainly in the middle of the bush, and there is also a color change in the lower part, then the plant lacks nitrogen.

Diseases and pests

The most dangerous diseases for the culture are fungal infections. Two types of infection are the most difficult to defeat: tissue necrosis and root rot. The smallest spores of the fungus are carried by air masses and affect mainly weakened plants that are in conditions of excessive moisture. 

Necrosis

The disease manifests itself in early spring. If the youngest shoots turn red, and then turn yellow and dry, then the point is infection with a fungus. Affected bushes should be treated with fungicides, dried shoots should be removed and burned. Deep pruning is carried out to healthy areas of wood, after which the treatment with preparations is repeated.

Root rot

The lesion is also caused by a fungus present in the soil. The disease actively develops with excessive watering with stagnant moisture, mainly in the cold season. Root disease is manifested by general inhibition of growth and lethargy of boxwood. Progressing, root rot leads to the fact that the leaves turn yellow on individual shoots, and then the whole plant.

At an early stage of the disease, when only individual branches have turned yellow, boxwood can be removed from the soil, cut off all damaged parts of the roots, replace the substrate in the planting pit with the obligatory laying of drainage. Sand must be mixed with fresh soil. At a late stage, with the loss of more than half of the green mass, it is almost impossible to save boxwood.

Boxwood galitsa

Pest infestation first appears as yellow blisters on the leaf surface. Tubercles form on the back of the plate, in which worm-like orange larvae develop. Young gall midges feed on boxwood leaves, and for the winter they go deep into the wood, in order to come to the surface in spring and repeat the breeding cycle in the stage of adult insects.

With prolonged infection, the leaves and entire shoots of the box dry. Gall midges should be dealt with in a complex manner, removing the affected areas of the shoots, conducting a double treatment with chemicals (Tagor, Aktara) with a break of 10 days. Be sure to spray the plants next season in early May, when the surviving gall midges enter the breeding season.

Boxwood Firing

An insect resembling a small moth, the most dangerous enemy of boxwood plantings in Europe, entered Our Country in 2012, but managed to spread over large areas and destroy hectares of groves on the southern coast of the Black Sea. Once on plants, insects multiply rapidly, clouding the bushes with sticky cobwebs. Boxwood leaves turn yellow and curl, they are eaten by small bright moth caterpillars.

When a pest is found, plantings are urgently treated with specialized biological preparations. Moreover, for insects at different stages of development, separate insecticides are provided: Dimilin, Decis Pro, Fastak, Fury. Spray the crown, trunks and all the soil near the trunk, as well as between plants.

spider mite

If the leaves become covered with yellow patches, and later lose color and dry, you should check the boxwood for the presence of small mites on the underside of the leaf blades. Pests appear in hot weather with low humidity and feed on juice from living leaves.

At the initial stages of infestation, microscopic mites can be washed off plants with soapy water. So you can prevent the whole bush from turning yellow. In case of severe lesions, it will be necessary to treat the plantings with chemicals.

What to do if boxwood dries and turns yellow

If individual leaves or entire branches turn yellow, and no pests or diseases are found, a series of measures should be taken to save the plant.

The main measures for the treatment of drying boxwood:

1. If the reason that the bush turned yellow is a sunburn, a screen should be placed next to it, sheltering from direct sunlight.
2. With high soil compaction, plantings are dug in, making a shallow groove, slightly increasing the trunk circle.
3. Boxwood roots occupy the uppermost layers of the soil and can suffer from moisture changes. Around the boxwood, which has turned yellow, mulch should be laid with a layer of 1 cm, at least 15 cm in diameter from the trunk.
4. Adjusting watering often helps bushes recover quickly. Proper, abundant top dressing allows you to build up the leaf mass and avoid further yellowing.
5. An important stage in the treatment of bushes is the complete removal of all parts of the plant that have dried up or turned yellow. Shoots are removed to healthy leaves, checking the condition of the wood on the cut.

Preventive measures

It will not be possible to return the color to boxwood, which has turned yellow. Affected branches will have to be removed and the formation of the bush must be started again. It is much easier to take care of the plants in advance.

Prevention of discoloration and drying of boxwood includes the following activities:

1. Regular removal of garden debris (leaves, branches) from the trunk circle and the center of the bush. So you can avoid the reproduction of pathogenic spores and bacteria.
2. Annual thinning of the crown, especially in the center. Remove excess shoots until the location of the internal branches in the shrub can be accurately considered.
3. Advance installation of screens or visors from the spring sun. Work is carried out no later than mid-February. You can simply cover the boxwood with an opaque breathable material.
4. Ensuring a sufficient drainage layer even at the stage of laying planting pits. If the bush has already turned yellow from waterlogging, you can try to carefully dig it out, pour at least 10 cm of pebbles, bark, coarse sand, gravel under the roots. After that, plant the plant in place again.

Be sure to carry out regular top dressing of boxwood. In autumn – with a potassium content, to maintain frost resistance. In spring, complex compositions with the obligatory presence of nitrogen. In the middle of the season, if the leaves are bright, green and not a single shoot has turned yellow, boxwood can only be watered without adding fertilizer.

Conclusion

If the boxwood has turned yellow, it is not yet time to despair and discard the bush. By finding out the cause in time and providing proper care, you can return the attractiveness of the plant. When individual leaves or shoots turn yellow, this is a signal from boxwood about trouble, having dealt with which, you can safely grow more than one beautiful plant, garden sculpture or a whole hedge.