What causes cherry tree leaves to turn yellow?
The turning of Cherry tree leaves from green to yellow is a common phenomenon in many parts of the world due to a variety of environmental and biological conditions. The yellowing of the leaves can be caused by several factors ranging from a lack of nutrients to disease and pests.
Potassium is an important nutrient for the health of a Cherry tree’s leaves. A deficiency of potassium can cause the leaves to turn yellow and an accumulation of too much of the nutrient can also have the same effect. According to Blain Hopwood, an expert from the Oklahoma State University, in order to prevent Yellowing, the soil must contain an adequate amount of potassium.
Iron deficiency can also lead to Cherry tree leaves turning yellow. A lack of iron restricts the tree’s ability to create chlorophyll and make the leaves turn pale. To replenish iron levels in the soil, it is recommended to supplement the soil with an iron fertilizer.
A fungal pathogen called Septoria citri can also cause the leaves of the Cherry tree to turn yellow. How the fungus spreads can be variable, from rain splashes, to wind and contaminated tools. To control the infection, it is important to prune and remove the yellow leaves before the pathogen is spread further.
Pest infestations by mites and aphids can also lead to yellowing of the leaves of the Cherry tree. Straw Toevs, an entomologist from the University of Netherlands, says that a combination of regular pruning and applying safe insecticides can easily control the pest population and prevent the leaves of the tree from turning yellow.
Finally, other environmental factors such as extreme temperatures and prolonged drought can cause the leaves of the Cherry tree to turn yellow. The leaves of the tree will often yellow if there is an absence of sunlight due to heavy shading or partial eclipse. Extreme temperatures can also accelerate the process of chlorophyll degradation and cause the leaves to turn yellow.
II. Nutrient Deficiency
Nutrient deficiency caused by waterlogged soil or phosphorus excess is another cause of yellowing leaves in cherry trees. Waterlogging restricts root uptake of both nitrogen and sulfur and phosphorus excess leads to chlorosis, a condition in which the leaves lack green pigment and turn yellow. In addition to this, the lack of nitrogen can lead to the foliage yellowing due to a chlorosis-like disorder.
To address nutrient deficiency, farmers may use a mineral fertilizer to boost the soil with necessary nutrients like nitrogen and sulfur. Dave Baker, a plant scientist from the University of Wisconsin-Madison, suggests regular testing of soil to assess the health of the crop and provide a solution if required.
Incorrect fertilizer application can also lead to yellow leaves in cherry trees due to an accumulation of nitrogen of the soil. Far too much nitrogen can lead to foliage that is explosively green in color which is caused by the overwhelming intake of nitrogen. In this situation, the trees can be brought back to health by dividing the doses of applied nitrogen and reducing it over time.
Finally, a lack of zinc in the soil can also interfere with the development of the tree’s foliage, leading to yellow leaves. The absence of zinc limits the production of chlorophyll which causes yellowing. Zinc can be replenished by applying a zinc-containing fertilizer to the soil.
III. Fungal Pathogens
A variety of fungal pathogens can cause cherry tree leaves to turn yellow. Many fungal spores can spread through contact with leaves, soil, and tools. The fungus Septoria citri, for example, is a common agent in cases of yellowing leaves in cherry trees. The symptoms are small black spots appearing on the foliage accompanied by yellowing.
To manage the infection, the fungus can be controlled in the early stages of infection through pruning and removal of affected parts. Additionally, adequate fungicide should be applied to maintain the healthy condition of the tree. According to Marilyn Driscoll, a horticultural specialist from the University of California, using less toxic fungicides can reduce the long-term damage to the environment.
Apart from Septoria citri, two other known agents of fungal infection are the powdery mildew and the brown spot. While powdery mildew affects both foliage and fruit, the brown spot leaves small black spots on the leaves of cherry trees. To tackle these problems, regular inspection of the tree, removing the debris and pruning infested branches are all recommended solutions.
IV. Heat Stress
Another common cause of yellowing leaves in cherry trees is heat stress. When temperatures increase, chlorophyll can break down which alters the color of the leaves to yellow. Heat stress can be prevented and managed by ensuring that the tree is planted in an area with ample shading.
One of the best strategies to reduce heat stress is the use of mulch or cover crops such as oats, rye or clover. Mulch prevents the sun’s radiation from penetrating the soil and helps to keep the temperature down, according to Patrick Lock, an agronomist from the University of Michigan.
Along with physical shading, irrigation is highly recommended during periods of heat stress. Spraying deep and infrequent water over the cherry tree helps to reduce the temperature and improves the health of the plant. However, irrigating too much can also be deleterious and lead to other issues.
Finally, irrigation combined with pruning and a light application of fertilizer can help maintain the health of the tree and boost the levels of chlorophyll, addressing the problem of yellow leaves.
V. Disease
Various diseases can also cause yellowing leaves in cherry trees, such as the leaf curl fungus, which is caused by cool, wet weather. The symptoms are leaves curling and yellowing, accompanied by white or pink patches on the underside of the leaf.
To prevent and manage the disease, infected leaves should be removed promptly, and pruning of the tree should be performed. The exposed bark should be sprayed with a copper-based fungicide, according to Dr. Jon LaPier, an expert from the University of Maryland.
Another common disease is the bacterial canker which occurs when the tree is infected with a bacteria called Pseudomonas syringae. The symptoms are yellowing and wilting leaves, along with reddish-brown lesions on the bark or branches. It is highly recommended to spray the tree with copper-containing fungicides to manage the disease in its early stages.
Finally, the twig blight is another disease that affects cherry trees. The symptoms are dying of the branches and yellow leaves. In this situation, it is important to prune affected branches, remove the debris and apply fungicide.
VI. Pests
In addition to diseases, pests can also lead to yellowing of the leaves of cherry trees. Common pests such as mites and aphids suck the sap from the tree causing stunted growth, yellowing, and wilting of the leaves. To prevent and manage these pests, dedicated insecticides should be applied, as prescribed by Dr. Alison Fox from the University of Oxford.
Mites are also a common pest affecting cherry trees. These mites feed on the tree’s leaves, causing yellow spots in its leaves. The best way to tackle the problem is to identify the species of the pest and apply targeted insecticides according to its label instructions.
Regular inspections of the tree should also be conducted to make sure there is no sudden or unexpected infestation of pests. In addition, a combination of preventive measures such as natural predators, companion planting, and physical barriers should be considered.
VII. Poor Soil Conditions
Generally speaking, soil compaction and nutrient imbalance can lead to poor conditions in cherry trees, eventually leading to yellowing. To prevent such problems, it is essential to ensure the soil structure is maintained by aerating the soil or using cover crops such as oats, barley, or clover.
As for nutrient imbalance, testing the soil regularly for pH, nitrogen, phosphorus, and potash are vital for proper assessments. When the soil does not contain sufficient levels of these nutrients, adding compost and fertilizer can be useful for restoring the balance in soil.
Excess water can also be a problem in soil and lead to yellowing leaves. Overwatering can deprive oxygen from the roots, leading to weak and yellow foliage. David Lysk, an expert from the Royal Horticultural Society, suggests planting cherry trees in areas with well-draining soil and avoiding excess water in these areas.
VIII. Light Conditions
Finally, excessive darkness or too much light can both cause Cherry trees to yellow due to a lack of or interference with photosynthesis. If the soil and environment around the tree is shady most of the time, the tree can struggle to process the light effectively and its foliage may yellow.
Alternatively, overexposure to sunlight can cause stress, leading to yellowing leaves. This occurs because when the tree is in direct sunlight, it is not able to cool itself sufficiently, leading to the depletion of chlorophyll and a yellowing of the foliage.
To prevent this, it is important to limit the amount of direct sunlight the Cherry tree receives. Placing screens or temporary shade for the tree can help reduce direct sunlight and help improve its health. Additionally, it is also important to provide adequate water and fertilizer to offset any possible deficiency.
