Why Is Your Purple Shamrock Turning White?

Purple shamrocks are one of the most sought-after plants for gardeners and other plant lovers. Many of these plant-lovers know of this native South American plant’s ability to bring life and color to any garden. Although it is generally a healthy and long-living plant, it isn’t invulnerable to diseases and infections. 

Your purple shamrock is most likely turning white due to fungi such as powdery mildew or rust fungus. Other common causes are pests such as the mealybug, or your shamrock has suffered sunscald from too much direct sunlight.

The rest of this article will cover several crucial topics surrounding this plant, such as what these white spots may be and how to identify and treat white spots on your shamrock plant.

Most Common Causes of Purple Shamrocks Turning White

When your vibrant purple shamrock leaves start turning white, it is cause for concern. The color change is almost always a definite sign of your plants’ ill health and you should act on this problem as soon as possible. There are several main culprits behind this change in your shamrock, which I will explore below, 

Powdery Mildew

Powdery mildew is a common disease in many plant species caused by several species of fungus from the order  Erysiphales. When powdery mildew infects your shamrock plant, you will first notice a thin layer of white patches on top of one or more leaves.

This thin, whitish layer becomes thicker as the plant becomes more infected. These white spots will assume a circular shape and may also begin to appear on the plant’s flowers, stems, and fruits.

These fungi proliferate in warm and damp conditions and spread utilizing airborne spores that are challenging to control. Unfortunately, outside of a fungicide, there is no other solution for powdery mildew. However, you can prevent it from getting worse! 

Rust Fungus 

Rust is an equally dangerous fungal disease that can cause immense harm to your shamrock plant. These diverse fungi from the order Pucciniales land on plants in the form of spores, invade the plant tissue and create fruiting bodies on the surface and tissues of leaves and petioles of plants.

The rust fungus collects on purple shamrock leaves and leaves and leaves orange, yellow, or rust-colored spore masses on the outside of plants. 

After a time, the fungi will leave a white, powdery residue. It spreads from the leaves to specific parts of the plant as the infection gets more severe. Some of the most common infection areas include its leaves, petioles, tender shoots, stem, and fruits. 

Unfortunately, like many other infections, people tend to ignore this rust disease until it’s too late. Although most rust infections are mild, some are severe enough to kill your plant. 

You should perform regular checkups on your plant and apply fungicide if you’re sure your shamrock is developing rust. You can also put some rust sulfur copper powder to prevent this disease from spreading.

Mealybug Infestation

Mealybugs are a common pest in homes and gardens which can cause leaves to turn white. These tiny insects are relatives of aphids and secrete a white waxy layer to protect themselves when feeding on plant sap. You may identify them by the white cotton-like masses or powdery white residue they leave on the plant.

Sunlight Damage

If your shamrock plant can suffer when placed in direct sunlight in the hot summer months. Sunscald in plants is similar to human sunburn, except the plant leaves turn yellow or white instead of red. When the plant tissue becomes damaged, it will not repair itself and you should remove the damaged leaves and relocate your shamrock to a shaded area. 

How Can You Identify White Spots on Purple Shamrock?

You can identify white spots on a shamrock by inspecting its leaves and stems. Look for fungal spores or white cottony residue of the mealybug. Large areas of white discoloration without other symptoms could be signs of sun damage. 

You can identify white spots on a purple shamrock by:

  • Checking at its stems and flowers
  • Look for tiny oval mealybugs 1-4mm (0.03-0.15″) long. 
  • Checking the top and underside of its leaves.

If you notice that your shamrock shows brown discoloration on its leaves, check out my article: Brown Spots on Shamrock Leaves: 3 Causes and Fixes

How To Treat White Spots on Your Shamrock Plant

You can easily treat white spots on your shamrock plant by:

  • Spraying it with fungicides.
  • Spraying with neem water for pests and fungus
  • Uprooting or cutting off infected parts
  • Avoiding direct sunlight.

Cutting off the leaves on the plant where the fungal disease is spotted will prevent the disease from spreading to other parts. For many cases of a powdery mildew infection, spraying fungicides and neem water is all you would need to do.

Fungicides like the Garden Safe Fungicide from Amazon are good options for your plant. It’s organic, ready-to-use, and functions as an insecticide and miticide.

Rust, however, is a slightly more severe fungal infection. Plant experts commonly recommend uprooting the whole plant when it is infected with this obligate plant pathogen to prevent it from spreading to other plants.

How To Care for Your Purple Shamrock

You can prevent fungal and pest attacks that damage leaves, by taking proper care of your shamrock plant. You should ensure you follow these pant care considerations.

Prune and Water Your Plant Properly

Pruning is essential to nurturing and caring for a purple shamrock plant. These colorful plants produce a lot of dead foliage all year round. To ensure your plant stays healthy, it would greatly help if you take off the dead parts before their dormant months.

Additionally, water your plant in moderation. Excessive watering could make your plant more susceptible to infections like powdery mildew. At the same time, watering too little is bound to cause your plant to wilt, so try to strike a balance.

As a general rule of thumb, only water if the topmost layer of the soil is dry. In its dormant months, leave it alone until you see some new leaves sprout.

Bottom watering your plants is also a good alternative. Since water comes from the bottom of the soil to the top with this method, the leaves generally stay dry.

Use Healthy Fertilizer

Providing your plant with rich fertilizer is arguably one of the most important ways of keeping it healthy. Ensure the fertilizer is liquid and diluted, and apply bimonthly to keep your plant healthy. Additionally, ensure you release this fertilizer slowly to avoid oversaturating the soil.

During its dormant months, do not apply fertilizer for any reason. These plants don’t take in nutrients or water during inactive periods. Instead, set it aside until new leaves start to sprout after their dormancy.

Always remember that as good as fertilizer is, it can have downsides when it’s overused. Excessive fertilizer in the soil can cause nutrient imbalances, eventually leading to problems. If you would like to learn more about fixing an over-fertilized plant, please check out my article: How to Treat Fertilizer Burn on Plants (Gardener’s Guide)

Usually, fertilizer is suitable for a plant in moderation, but during your shamrock’s dormant period, the nutrients remain unused in the soil. Further addition of fertilizer will increase them and eventually cause problems like wilting, bleached leaves, and in severe cases, death.

Maintain Regular Humidity and Sunlight

Exposing your purple shamrock to bright to medium indirect light is necessary when caring for it. Shamrock leaves can be pretty sensitive to sunlight. Like the similarly colored African Violet, they should never be left in direct sunlight as this can burn their leaves.

Also, these plants will thrive in typical indoor room temperatures (between 68-76°F) and humidity above 50%. Your plant will become dormant when the temperature is higher for extended periods. It might start to droop and shed all its leaves in response to the intense temperature.

Use Suitable Soil With a Well-draining Pot

One mistake many plant-lovers make is failing to use suitable soil for this plant. Contrary to popular belief, the ideal soil for this plant is loamy. The shamrock favors loamy soil because it retains a lot of moisture. In addition, this soil drains rather well compared to other soil types, allowing the roots to get enough air.

Although loamy soil is the best, other well-draining soil combinations will do. For instance, a mix between sandy and loamy soil drains well and is equally effective for the purple shamrock plant. 

Keep Your Shamrock Plant Indoors During Dormancy

These plants love to grow during fall and spring. However, they become dormant during summer and extremely hot weather. Purple shamrocks love to conserve their energy until the following fall and spring seasons. Usually, this dormancy is easy to spot as the plant leaves begin to yellow.

The Verdict

When healthy, a purple shamrock is a beautiful plant that can add color and life to any garden. However, it can easily get root and fungal diseases such as powdery mildew and rust. If you want to reduce the chances of this happening, ensure you adequately take care of your plant. 

Understandably it’s impossible to get it right all the time. However, that’s no reason to despair. White spots on your plants are far from fatal, especially if treated quickly. Fungicides and pesticides are a great fix for most problems, and indirect sunlight is vital for proper growth.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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