Explain why boxwoods turn yellow?

First cause: Parasites and diseases

Boxwoods are often subject to attacks by various parasites and diseases that can cause their leaves to turn yellow. Among the most common parasites are the boxwood aphid (Aphis buxi) and the box tree moth (Cydalima perspectalis). These small insects feed on the sap of boxwoods, weakening the plant and causing the leaves to yellow.

As for diseases, the fungus Cylindrocladium buxicola is responsible for the disease known as "cylindrocladium blight". This disease is characterized by dark spots on the leaves, followed by yellowing and premature leaf drop.

It is essential to closely monitor the presence of parasites and diseases on boxwoods and to intervene quickly to limit damage. Preventive and curative treatments are available to combat these harmful organisms and preserve the health of boxwoods.

Second cause: Unfavorable weather conditions.

Second cause: Unfavorable weather conditions

Boxwoods are sensitive to several unfavorable weather conditions that can lead to yellowing of their leaves. Among these factors, excessive moisture can be mentioned. Indeed, boxwoods are plants that prefer well-drained soil and a certain level of humidity, but an excess of water can lead to root problems and promote the development of pathogenic fungi.

Likewise, a lack of light can also influence the yellowing of boxwoods. These plants appreciate sunny or semi-shaded locations. A lack of direct light can lead to a decrease in photosynthesis, resulting in yellowing of the leaves, as the plant does not produce enough chlorophyll to ensure its normal growth.

Furthermore, extreme temperatures, such as late frost in spring or excessive heat in summer, can also affect the health of boxwoods. Sudden temperature variations can weaken the plants and disrupt their metabolism, causing stress that often manifests as yellowing of the leaves.

Finally, air pollution, strong winds, and the presence of harmful chemicals can also play a role in the yellowing of boxwoods. These external factors can weaken the plants and compromise their ability to absorb the necessary nutrients for their development.

In conclusion, unfavorable weather conditions can have a significant impact on the health of boxwoods and contribute to the yellowing of their leaves. It is important to consider these environmental factors to ensure the proper growth and development of these ornamental plants.

Third cause: Lack of nutrients

Boxwood plants can turn yellow due to a lack of essential nutrients needed for their growth. When boxwoods do not receive enough nutrients such as nitrogen, phosphorus, and potassium, their ability to produce chlorophyll, which is responsible for the green color of the leaves, can be compromised. The lack of nutrients can lead to a general weakening of the plant, making it more vulnerable to diseases and pests. It is therefore important to provide boxwoods with a balanced fertilizer to prevent nutritional deficiencies and maintain their health and vigor.