When it comes to caring for boxwood, you need to pay attention closely to the color changes of boxwood leaves to prevent serious diseases or damages.
Do you have a boxwood bush in your yard that’s not looking its best? If it has discoloration such as brown or yellow, then you may be wondering what’s going on.
Let’s take a look at what might be causing this problem.
What Causes Yellow Leaves on Boxwoods?
Is your boxwood turning yellow and brown? Here are some common reasons why.
Winter Damage
The cold winter months can wreak havoc on boxwood plants and cause discoloration. This is because boxwoods are not resilient to very cold temperatures and extreme weather conditions like wind and heavy snowfall.
To protect your boxwood plants from winter damage, make sure they are planted in an area where they will receive protection from the elements, such as a sheltered spot next to the house or fence line. Wrap them with burlap for extra insulation.
Root Rot
Root rot is another potential culprit for yellowing boxwood leaves. Root rot occurs when fungal pathogens enter the root system of the plant and begin to break down its cells, resulting in damaged roots that cannot absorb enough water or nutrients from the soil.
If left untreated, root rot can eventually spread throughout the entire plant causing it to become weak and eventually die off.
The best way to prevent root rot is by ensuring that your boxwoods are planted in well-draining soil so that excess moisture does not accumulate around the roots of the plant.
Nematodes
Nematodes are tiny worms that feed on plant roots, depriving them of essential nutrients and water needed for healthy growth. A severe infestation of boxwood evergreens may cause yellow spots or brown spots on its leaves as well as stunted growth due to nutrient deficiency caused by their presence in the soil.
Drought Stress
Boxwoods require consistent moisture levels in order to stay green and healthy; otherwise, they may suffer from drought stress which can lead to yellowing leaves or branches dying back due to a lack of water supply reaching them through their root system.
Pests Like Mites, Boxwood Leafminers, or Aphids
One of the most common causes of yellow leaves on boxwoods is pests such as boxwood mites, leafminers, or aphids. All three of these pests feed off of boxwood foliage and can cause discolored leaves.
Mites are small spider-like insects that feed on the sap of the plant; they will leave behind webs and discolored spots on the underside of the foliage.
The boxwood leafminer is an insect that burrows through the leaf tissue and creates tunnels or trails; they will leave behind a yellowish discoloration along their path.
Aphids are small pear-shaped insects that suck out the juices from plants; they also excrete a sticky substance called honeydew which can lead to mold and fungus growths on foliage.
You also need to investigate to see where the pests come from, especially if they come from other plants that grow next to boxwoods.
Salt Damage
Excessive amounts of salt can also cause discoloration in boxwoods, especially if you live in an area with salty soil or high levels of salt in the air due to road salt runoff or ocean spray.
Salt damage will cause browning at the tips or edges of your plant’s foliage first before progressing inward towards more green areas.
Macrophoma Leaf Spot
Macrophoma leaf spot is caused by a fungal disease that leads to circular spots appearing on your boxwood’s foliage, usually starting off as red then turning yellowish-brown with age.
This disease is most commonly seen during wet weather seasons and it typically affects older leaves first before progressing onto younger ones if left untreated for too long.
Volutella Blight
Volutella blight (boxwood blight) is another fungal disease that can affect boxwoods, causing them to have wilting stems and yellow/brown patches on their foliage; this often occurs during periods where temperatures fluctuate between warm & cold days (which encourages spore germination).
Aging
Lastly, aging can also cause yellowing leaves in boxwoods; this typically happens when plants get old enough that their foliage starts becoming less green over time (due mostly to a lack of nutrients being provided anymore).
How Do You Treat Yellow Leaves on Boxwoods?
If you want to save your yellow boxwood from decline, there are several steps you can take.
Trim By Up to â…“
The first step in treating yellow leaves is to trim the boxwood by up to â…“ of its total height. This will help reduce the amount of dead growth that can harbor disease or pests.
It’s important to use sharp pruning shears when trimming so that you don’t damage the remaining healthy foliage.
Be sure to make clean cuts at an angle slightly above a leaf node for the best results.
Use a Copper Fungicide in the Early Spring and Agiasn in Late Summer or Fall
Timing is key when using copper fungicide on your boxwood shrubs, as too much copper can burn or discolor foliage.
For best results, apply copper fungicides in early spring before new growth appears and again in late summer or fall after any new growth has matured but before cold weather sets in.
Keep an eye out for signs of fungal infection such as brown spots on the leaves which may require additional applications throughout the year.
Mulch
Adding a layer of mulch around your boxwood roots will help keep weeds away and retain moisture throughout hot summer days, both of which will help prevent yellowing due to dehydration or lack of nutrients from soil-borne microbes like fungi.
Use organic mulches such as wood chips, straw, or shredded bark for best results.
Water Regularly
Watering your boxwood regularly is essential for keeping it healthy and strong against fungus infections such as those responsible for yellowing leaves. Aim to water deeply but not too frequently.
Can a Yellow Boxwood Be Saved?
When it comes to reviving a dying boxwood shrub from browning leaves, there are many things you can do.
With proper diagnosis and treatment, you should have no trouble getting your boxwoods back into tip-top shape in no time!
If growing boxwoods is difficult for you, these substitutes for boxwood might be easier for you.
FAQs
What fertilizer is good for yellowing boxwoods?
For yellowing boxwoods, consider using a fertilizer specifically formulated for acid-loving plants, such as one with a higher nitrogen content and micronutrients like iron and magnesium to address nutrient deficiencies that may be causing the yellowing.
How do you make boxwoods greener?
To make boxwoods greener, ensure they are planted in well-draining soil amended with organic matter like compost to provide essential nutrients. Regular watering, especially during dry periods, and mulching around the base of the plants can help retain moisture and keep the soil cool, promoting lush green foliage.
*image by weha/depositphotos
