African violets are popular houseplants known for their ease of care and beautiful blooms. However, even with proper care, they can sometimes develop diseases or pest infestations, with the first visible signs often appearing on the leaves. Leaf changes are one of the first ways your plant will signal something isn’t right in its environment. Luckily, most African violet leaf problems are an easy fix!
Common Leaf Problems and Their Causes
The African violet plant can develop spots on its leaves from being misted or splashed with water. The African violet's fuzzy leaves can trap moisture causing fungal or bacterial leaf spot to form. Leaf problems can range from spots to discoloration, and understanding the causes is crucial for effective treatment.
1. Water Spots
Water spots are caused by a difference between leaf temperature and water temperature when water is dropped on an African violet leaf. Yellow or white ring and line patterns on African violet leaves can be caused by contact with cold water. There’s no way to undo water spots that appear; however, the spots don’t spread and won’t harm your African violet’s growth.
Prevention: Prevent water spots by bottom watering rather than top watering African violets. To avoid this, always water your African violet at the soil level by carefully lifting the leaves or with the bottom-watering method, never on the leaves or the center of the plant.
Bottom watering method for African Violets
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2. Powdery Mildew
If the spots on your African violet are white and powdery looking, this could be a fungal disease called powdery mildew. The first sign of powdery mildew on African violets is the appearance of a light powder that seems to cover the leaves and flowers. There may also be discoloration in the blooms. Powdery mildew could have formed because the plant lacks air circulation in a hot and humid environment.
Prevention: You can prevent powdery mildew by making sure there’s enough space between your plants to allow for enough airflow.
Treatment: To treat plants with powdery mildew, first isolate the affected plants to prevent the mildew from spreading. To help the plant, prune off the dead stems and leaves and isolate them from other plants since fungal issues can spread quickly between plants. Place the plant somewhere with more air movement and more light, and treat the plant with a copper fungicide. Try treating the plants with a homemade mix to begin with. Mix one tablespoon of baking soda with one gallon of water, and coat the infected plant with the mixture. If that doesn’t work, then you may have to use a fungicide made to treat powdery mildew.
3. Edema
Overwatering an African violet can also cause spots to appear on the leaves. Too much moisture in the soil of a houseplant can sometimes cause edema. Edema shows up as spots most often on the underside of the leaves, but occasionally on the top. These spots have a reddish coloration and will luckily not spread once watering is corrected.
Prevention: Water when the soil volume is 25% dry. This plant likes to be kept moist, but does not like to sit in soggy soil. Avoid getting the leaves wet, and the bottom-watering method is recommended. Place your plant in a sink filled with 2-4″ of water. Leave the plant to soak for up to 45 minutes. Test the top of the soil for moisture. If it still feels dry water a little from the top.
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4. Temperature Damage
If your plant has been exposed to temperatures below 55°F, it can cause damage. On the other hand, exposure to direct sun can also cause spots.
Prevention: Like many of us, African violets like to be cozy. And-also like us-they tighten and huddle up to conserve heat when they get cold. If your African violet’s leaves are curling under and turning brittle, they’re not warm enough! Your plant will be happiest in a space with a steady temperature of 68-70ºF. African violets like bright, indirect sunlight. But when they’re placed in hot, direct sunlight, their leaves can start to suffer.
5. Other Potential Leaf Problems
- Bacterial Blight: Looks like black rot attacking an African violet’s crown and roots. The spots that show up sometimes appear brown or dark red rather than black.
Treatment: To treat this disease, use sterilized scissors to cut away any leaves or roots that have spots or show signs of infection.
- Botrytis Blight: The first warning signs are gray blooms and a lack of growth at the crown. Then the leaves will start to develop fuzzy gray and brown spots. Finally, the African violet will wilt.
Treatment: To treat this disease, isolate plants that show signs of infection and use sterile tools to remove any portions of the plant that have spots. Use a fungicide to keep the infection from returning. Botrytis blight spreads quickly, so there’s no guarantee you’ll be able to save an infected African violet.
- Phytophthora Crown Rot: Some diseases that affect African violets don’t show up on the leaves at first; instead, some diseases target the crown or the roots.
Prevention: To prevent Phytophthora crown rot, avoid overwatering African violets and use a well-draining potting soil in a container that allows excess water to escape.
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Treatment: Treating Phytophthora crown rot is extremely difficult. In most cases, the best plan of action is to get rid of the plant, the soil, and the container to prevent the fungus from spreading to other African violets. If you decide to try to treat crown rots, you’ll need to remove the infected parts of the plants and replant the African violet in a new container.
- Root Rot: The main visible symptoms are leaves that turn yellow, wither, and fall off.
Prevention: Prevent Pythium root rot by allowing the soil to almost dry out between waterings.
Treatment: There isn’t a good treatment for root rot, so the best thing to do with an infected African violet is get rid of the plant and the potting soil.
- Rhizoctonia Crown Rot: The signs are wilting, collapsing, turning black, and dying.
Prevention: Prevent Rhizoctonia crown rot from developing by making sure your African violet’s soil is quick-draining and doesn’t hold on to excess water.
Treatment: There is no good way to treat this disease. Immediately remove the infected plant. Get rid of the plant and the soil without allowing it to come into contact with other plants.
- Foliar Nematodes: The most common visible symptom is wilting leaves.
Prevention: Prevent nematode infections by isolating new plants before bringing them into the same area as other plants.
Treatment: There’s no good treatment for foliar nematodes. While there are a few pesticides available that target foliar nematodes, you need a pesticide license to buy those.
- Cyclamen Mites: These mites are very tiny but can be seen with a magnifying glass. Cyclamen mites have eight legs and can be either white, yellow, or brown.
Prevention: The best way to prevent a mite infestation is to isolate new plants until you’re certain they’re not infected. Space plants so that they do not touch to prevent the spread of cyclamen mites. Also, be careful not to touch infested plants before working with non-infested plants.
Treatment: To treat a mite infestation without using a chemical treatment, you can spray neem oil or Leaf Armor on infected plants. Make sure to keep infected African violets isolated until the infestation is under control. Badly infested plants should be discarded. For valuable plants, spray with a miticide that is labeled for use on houseplants. Take the plant outside during mild temperatures and spray with insecticidal soap or products containing sulfur or tau-fluvalinate. Two or three sprays at three-day intervals may be required for mite control.
- Mealybugs: Signs of a mealybug infestation are fairly similar to other problems, including white specks on the leaves or stems, sticky honeydew on the leaves, or black fungus on the leaves. Mealybugs are tiny insects about 1/16 to ¼ inch in size and are covered in a sticky, white, powdery substance.
Prevention: The best way to prevent a mealybug infestation is to inspect new plants before bringing them home. Check both the plant itself and the soil for signs of mealybugs and their eggs. Avoid bringing these pests into the house by inspecting a new plant carefully, including the bottom of the pot, for mealybug eggs.
Treatment: Minor mealybug infestations can be treated by dipping a cotton swab in rubbing alcohol (70% isopropyl alcohol) and then touching any visible insects. Major mealybug infestations require a more drastic approach. Spraying neem oil or Leaf Armor on the leaves and stems consistently can sometimes treat a heavy mealybug infestation. Neem oil is non-toxic to people, so we prefer to start with neem oil first. If neem oil is not effective, you can use a chemical pesticide designed to target mealybugs. Take the plant outside during mild temperatures to spray. Two or three sprays at three-day intervals may be required. Alternatively, soil-applied insecticide granules containing imidacloprid will also control mealybugs.
General Care Tips to Prevent Leaf Problems
Having a disease or pest attack your African violets can be disappointing. The good news is that most diseases and pests are preventable with a little extra vigilance on your part. Here are some essential care tips:
- Watering: Make sure you water your African violet correctly. Check the soil, and make sure you’re watering correctly. If the top 2 inches of the soil are dry, it’s time to water. Overwatering is generally the cause of the bottom leaves of an African violet dying. Allow the soil to dry out more between waterings.
- Air Circulation: Provide adequate air circulation.
- Healthy Environment: Generally keep your plant healthy.
- Isolation: Also, isolate new plants to check for pests before placing them near the rest of your plant collection.
African violets can live for a long time. By following these guidelines, you can address these issues and maintain a thriving, beautiful African violet.
Other Common African Violet Problems
Besides spots on the leaves, African violets can suffer from other issues that affect their overall health. Here are a few common problems:
- Leaves Curling Under: If your African violet’s leaves are curling under and turning brittle, they’re not warm enough! If you’re certain your plant hasn’t caught a chill, too much sunlight might be to blame.
- Brown, Crispy Leaves: If you accidentally get your plant’s leaves wet while watering, and they’re exposed to direct sunlight, it can lead to brown spots and sunburn. African violets have delicate root systems that can easily struggle when exposed to overfertilization.
- Yellowing Leaves: Each leaf on an African violet will live about a year. As it nears the end of its life cycle, your plant will stop sending nutrients in its direction; instead, it saves that energy for higher-functioning foliage. African violets grow from the crown outward, so if you notice the leaves closest to the surface turning yellow, they’re probably on their way out.
- Limp and Droopy Leaves: This is a sign your plant can’t properly deliver nutrients to its cells. If your plant isn’t getting enough water, it won’t be able to keep its leaves healthy and firm. The sneaky cousin to underwatering, overwatering can be even more dangerous to your plant. When an African violet stays in oversaturated soil for too long, air can’t reach the roots. This creates prime conditions for root rot and fungus.
- Failure to Flower: Unfavorable environmental conditions such as low temperatures, poor soil aeration, wet soil, or excessively dry air contribute to flower failure.
- Petiole Rot: The symptom of petiole rot is a rust-colored spot that appears where the stem of the leaf touches the pot.
African violet flower buds may fail to open, turn brown, and fall off. Lack of light, water, fertilizer, or even waiting too long to repot can all cause African violets to stop blooming. To encourage African violets to bloom, you must figure out which area of care is lacking. Once you address that problem, your African violet should resume blooming again.
Table 1. Common African Violet Problems and Solutions
| Problem | Cause | Solution |
|---|---|---|
| Water Spots | Cold water on leaves | Bottom watering |
| Powdery Mildew | Lack of air circulation, humidity | Improve air flow, fungicide |
| Edema | Overwatering | Allow soil to dry between watering |
| Curling Leaves | Cold air or direct sunlight | Move to warmer location or indirect light |
| Brown, Crispy Leaves | Wet leaves exposed to sunlight, over-fertilization | Avoid wetting leaves, flush soil |
| Yellowing Leaves | Natural aging, nutrient deficiency | Remove old leaves, fertilize |
| Limp and Droopy Leaves | Underwatering or overwatering | Adjust watering schedule |
| Failure to Flower | Low temperatures, poor soil aeration, wet soil, or excessively dry air | Provide better environmental conditions |
| Petiole Rot | Fertilizer salts accumulate on the rim of the pot and the soil surface | Avoid over-fertilization of plants, and be sure to use a salt-free source for watering, such as rainwater |
Wilting can occur for a variety of reasons, with the most common being overwatering or underwatering. Check the soil, and make sure you’re watering correctly. If the top 2 inches of the soil are dry, it’s time to water.
Diagnosing a Common African violet Plant Disease
Whether you’re just starting out or are a seasoned grower, African Violet Resource Center has everything you need to help your plant grow vibrant and strong.
