Yellowing leaves on plants can be a normal process. Older leaves naturally turn yellow and fall, replacing fresh, new growth. In the autumn, tree leaves naturally change colors and fall.
Neither of these instances is cause for concern, but if your plant, shrub, or tree is exhibiting lots of yellowing leaves and it is not the right time of year for leaves to change, you may have a problem with iron chlorosis, a common nutrient deficiency.
If a plant cannot get enough iron into its leaves, it will not be able to conduct photosynthesis and create chlorophyll, the source of the leaves’ green color.
When plant leaves become yellow in a uniform manner, this is chlorosis. It is an indication that your plant is not producing enough chlorophyll.
This disorder has many causes, including:
- Herbicide misapplication
- Temperature extremes
- Nutrient deficiency
- Disease pathogens
- Too much water
- Too much light
- Too little water
- Insect feeding
- Root damage
Because so many types of stressors can cause chlorosis, it’s easy to see that there is no single answer to preventing and treating the condition.
Generally speaking, best practices in plant care will help you avoid this problem in your plants.
If you do have trouble with yellowing leaves, it’s a good idea to review your plant care practices and correct any problems with light, temperature, water, soil, fertilizer or pests.
In this article, we’ll discuss some of the conditions that cause chlorosis in plants and provide sound advice on how to fix this common plant problem. Read on to learn more.
How to Treat Chlorosis
Chlorosis Caused By Nutrient Deficiency
The most common form of chlorosis is iron chlorosis. This happens when your plant is not receiving enough iron. Iron chlorosis can be caused by a lack of iron in the soil, or it may be that your plant cannot absorb the type of iron present.
A plant with iron chlorosis will have yellow leaves with green veins. To correct this problem, you’ll need a chelated iron plant supplement.
Apply this to the soil according to the packaging directions. For acid-loving plants, you may also wish to add a sulfur product to further acidify the soil.
How Can You Tell If Your Plant Has Iron Chlorosis?
Iron chlorosis typically affects new growth before affecting old growth. With this problem, the body of the leaf will turn yellow, but its veins will stay green.
In very severe cases, the leaves may turn completely white and fall. The growth of twigs and branches may also be stunted, and the plant’s stems and limbs may die.
Badly affected plants may not bloom or produce fruit.
Why Does Iron Chlorosis Happen?
This problem may happen because there is not enough iron in the soil or because the soil pH levels are too alkaline. This prevents plants from being able to uptake the iron that is in the soil. The best way to determine what is wrong with your soil is to perform soil testing.
You can test your soil using a soil test kit or contact your local cooperative extension service for assistance. Testing your soil will help you determine its pH level and texture. This is all valuable information.
What Can You Do To Treat Iron Chlorosis?
If your soil testing reveals that your soil is too alkaline (higher than 7) you can add soil amendments, such as sulfurs and sulfates, as mentioned. This will make it easier for your plants to access the iron in the soil.
Generally speaking, too alkaline soil may inhibit plants’ iron absorption. The soil pH level of 6.0-6.5 is best for most plants.
Acid-loving plants are happier with soil with a pH level as low as 4.5. You can achieve this level and improve your plants’ ability to uptake iron by amending the soil with a wide variety of products, such as:
- Aluminum sulfate
- Ferrous sulfate
- Iron chelates
- Iron sulfate
- Sulfur
If your soil test shows that your soil is lacking in iron, you can also add micronutrients to your soil. Additions of iron and manganese can help resolve chlorosis problems; however, you will also want to improve the quality of the soil.
Some nutrient supplements can simply be sprinkled on the soil and watered in. Others need to be worked into the soil for best results. Be sure to follow the packaging instructions closely.
There are also nutrient supplements that can be injected into the soil using a root feeder. This might be a more viable option for the landscape’s large plants, shrubs, and trees.
Natural Soil Amendments Provide Steady Support
Plants in the landscape will also benefit from adding 2”-4” of organic mulch (e.g., leaf mulch or compost) to help keep the soil uniformly moist and maintain a steady addition of nutrients into the soil as the mulch decomposes. This also helps keep the soil at the proper pH level.
Begin by simply applying several inches of organic compost around the base of affected shrubs or trees.
Top this off with a thick layer of bark mulch. The compost will bring more nutrients to the soil, and the mulch will help keep moisture levels consistent.
With time, the mulch will also break down and nourish the soil. When this happens, you can simply turn it under and add more compost and mulch. This will help build the good quality soil that is absolutely essential to preventing and correcting problems with iron chlorosis.
Brighten Leaves With Foliar Feeding
In addition to correcting soil pH levels and introducing nutrients, you can also give your plants’ yellowing leaves a temporary boost with foliar feeding.
Improving the soil and adding nutrients are long-term solutions, but they may not have very quick results. Indeed, soil improvements and amendments may take a year to fully resolve the issue.
To improve the appearance of your plants in the meantime, you can deliver a dose of iron by spraying the plants’ leaves with an iron compound.
Spray the leaves liberally with a soluble organic iron complex, iron chelate, or iron sulfate solution.
Repeat the treatment once every couple of weeks throughout the growing season. This will help keep the plant green, but it will not correct problems with the soil.
Identify the Leaf Yellowing Pattern & Treat Nutrient Deficiency with the Best Fertilizer
Identify & Correct The Problems That Lead To Chlorosis
Yellowing leaves are typically one of the first symptoms of a wide array of environmental stresses.
Prolonged periods in a less-than-ideal environment will cause stunted growth, yellowing leaves, and overall failure to thrive. It’s important to pay close attention to your plants and note any negative symptoms and their progression.
When you notice something is awry with your plants, chances are very slim that the problem will correct itself.
Negative symptoms like chlorosis are your plants’ cry for help. Examine the plant and its living conditions carefully and make corrections as needed.
Very often, plants show symptoms that seem to be caused by pests or diseases, but the real root cause is the plants’ environment.
This type of stressor is termed an “abiotic injury.” This condition is caused by too much or too little water, too much or too little light, or poor soil.
Chlorosis Caused by Overwatering
For houseplants, one of the main causes of chlorosis is overwatering. When plants’ roots are consistently soggy, the plant simply cannot “breathe” or process nutrients correctly.
Also, soggy roots quickly become rotten, causing the plant to succumb to fungal and bacterial infections. This is also a prominent cause of chlorosis.
Weakened plants are more subject to pest infestation, and pests will further stress the afflicted plant and cause even greater problems with yellowing.
If the problem that caused the yellowing, to begin with, is not corrected, the plant’s leaves will turn brown, and it will die.
In the case of potted or container plants, you may be best off simply repotting with an all-new, fresh potting mix.
Fix Chlorosis With Excellent Plant Culture
Remember that iron chlorosis begins in the soil. To avoid it, you must provide a good environment for your plants right from the start. To correct it properly, you must test your soil and make the correct changes.
When you provide your plants with excellent growing conditions, you will have hit upon the long-term solution to preventing and treating chlorosis.
Plants provided light, airy, nourishing, well-draining soil, the right amount of light, air, and water are unlikely to experience excessive yellowing of leaves.
Gary Antosh
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