Few plant pests and diseases, as well as cultural problems (often referred to as physiological disorders), like falling leaves and flower buds, can be avoided. It is much simpler to keep pests and diseases from harming plants than to get rid of them once they have already done so. Here are some suggestions for avoidance.
- Purchase plants from reliable vendors.
- Examine plants before purchasing.
- Keep an eye out for infestations.
- Don’t substitute garden soil for potting compost, as it may contain pests, seeds, or diseases.
- Keep dead flowers and leaves away from plants.
- When repotting plants, inspect the root balls for soil pests.
- Never use infected plants for propagating new plants.
Unfortunately, sometimes you can do everything right, and you can still have an unhealthy plant. We’ll cover the most common houseplant problems and solutions below.
Note: The chemicals permitted by law change in one country, and one state are from others. So, if prevention doesn’t work, consult your neighborhood nursery or garden center about the best insecticide to use for your particular issue.
Houseplant Pests
Aphids
The most prevalent pests of houseplants are aphids, also referred to as greenflies, aphis, and aphides. These small, typically green sap-sucking insects attack soft leaves, shoot tips, flowers, and other plant materials, sucking sap and causing mottling and distortion.
Additionally, they excrete honeydew, which draws ants and promotes the growth of sooty mold, a disease.
Solution
When aphids are noticed, spray the area with an appropriate insecticide. Repeat throughout the summer every 10 to 14 days.
Cyclamen Mites
Various plants, such as cyclamen, pelargoniums, saintpaulias (African violets), and impatiens are infested by cyclamen mites (Busy Lizzies). They are tiny, resembling eight-legged spiders, and they assemble in groups on the undersides of leaves. They eat sap, which causes leaves to wrinkle and turn dark. As a result, flowering is cut short, and the buds may change shape or even fall off.
Solution
Eliminate and burn any leaves or flowers that are severely infected.
Use an acaricide spray.
To stop the mites from spreading, destroy plants that are seriously infected.
Mealybugs
Mealybugs are white, waxy, woodlice-like pests that typically infest ferns, palm trees, azaleas, and hippeastrums and live in groups. They suck sap, which results in distortion, vigor loss, and yellowing of leaves. They also expel honeydew, which promotes the growth of ants and sooty mold.
Solution
Light infestations should be controlled and removed with cotton swabs dipped in methylated spirits (rubbing alcohol). Then, burn seriously infected plants or spray them with an appropriate insecticide.
Red Spider Mites
Also referred to as greenhouse red spider mites, they are tiny, typically red, and have eight legs. They resemble spiders. When there is a severe infestation, they suck leaves, which results in mottling and webs. In addition, they are unsightly, restrict airflow around the plant, and complicate eradication.
Solution
Spray a suitable acaricide and mist spray with clean water daily (avoid spraying soft leaves or flowers).
Scale Insects
Female scale insects lay their eggs on swollen, waxy-brown discs that are typically stationary.
Solution
Use a cotton swab dipped in methylated spirits to wipe away young scale insects (rubbing alcohol). However, established colonies are challenging to get rid of, and it’s best to burn severely contaminated plants.
Thrips
Thrips are tiny, dark-brown insects that resemble flies and jump from one plant to another. They puncture flowers and leaves, sucking the sap and causing mottling, silvery, and streaking— small globules of a red liquid that eventually turn black and form on the undersides of leaves.
Solution
Burn seriously infected plants or spray them several times with an appropriate insecticide to control them. Maintain moisture in the compost because these insects’ damage is exacerbated by dryness.
Vine Weevils
Vine weevils are harmful in all life stages, including the adult and larval.
Adult vine weevils have short snouts and resemble beetles. They chew every component of plants. The larvae live in compost and gnaw on roots. They are fat, legless, and creamy white with brown heads.
Solution
Immediately spray the leaves and water the compost with an appropriate insecticide. Kill plants that are seriously infected.
Whitefly
When disturbed, these tiny, moth-like insects flutter from one plant to another. They are usually found on the undersides of leaves, sucking sap, distorting the plant, and excreting honeydew, which promotes the growth of ants and sooty mold. They have a mealy or powder-like covering.
Solution
Complete eradication is difficult; several applications of a suitable insecticide every five days are required.
Houseplant Diseases
Black Leg
Black leg is a disease that primarily affects cuttings, particularly pelargoniums; the bases turn soft and black.
Solution
Cold, wet, airless compost promotes this, so when taking cuttings, make sure the compost is well aerated. For rare or unusual varieties, remove cuttings, cut off the blackened area, and re-insert the base in new compost. If cuttings are infected, it is best to remove and destroy them.
Botrytis
Gray mold, or botrytis, attacks tender parts of plants like flowers, shoots, and young leaves and coats them in a gray, furry mold.
Solution
- Cut off and destroy infected parts for control.
- Use an appropriate fungicide to spray infected plants.
- Take out any dead flowers to prevent further growth.
- Avert excessive water and still, damp air.
Damping Off
Assaults seedlings shortly after germination, turning them black and causing them to fall over.
Solution
To control, thinly scatter seeds in compost that has been well-drained and place them in a warm, well-ventilated area. Don’t overwater the compost.
There are other ways to maintain plants’ health, fend off pests and diseases, and grow them healthfully with sufficient moisture, food, and air circulation.
Powdery Mildew
Powdery mildew is a plant disease that causes a white, powdery layer to form on surfaces. It typically affects stems, flowers, and leaves in the spring and summer.
Solution
To control, cut off any leaves, stems, or flowers that are seriously infected. Increase ventilation and maintain a dry environment.
Rusts
Rusts are complicated diseases that pose more of a threat outdoors than indoors. Raised rings of brown or black spots appear as a result. Plants become unhealthy and start to look sickly.
Solution
Increase ventilation and remove and burn infected plants as a control measure. Never multiply from infected plants.
Sooty Mold
A black fungal disease known as “sooty mold” develops on leaves, stems, and flowers with honeydew. This plant disease will start in small clusters before eventually covering the entire surface.
Solution
Spray a suitable insecticide on the affected area to control sap-sucking insects. Use a damp cloth to get rid of the black growth on the leaves. It is best to cut off flowers.
Viruses
Viruses are microscopic particles that attack plants (and animals), disrupting the tissue but rarely immediately killing the host.
Solution
Burn severely infected plants and regularly spray sap-sucking insects with an appropriate insecticide (likely what caused the issue with your plants).
Non-Chemical Pest & Disease Control
- When you think you might have red spider mites, mist plants with a bottle of clean water.
- Remove dead flowers and leaves as often as possible.
- Utilize insecticidal soaps, which work wonders against various insects and mites.
- Use other insects and mites to control pests while researching biological controls. These are particularly appropriate when insects have become resistant to chemical pesticides. Aphids, red spider mites, caterpillars, mealy bugs, soft-scale insects, thrips, whiteflies, and vine weevil larvae are just a few examples of pests that have biological controls. But once more, seek advice from your local garden center.
Environmental Issues
These conditions, also known as physiological disorders, are brought on by environmental issues rather than by diseases or pests.
Wilting
Wilting has many causes, including too much or too little water. And pests in the soil that consume and destroy roots.
In most cases, lack of water causes plants to wilt; if the compost is dry, water the plant several times.
Alternately, place the plant in a bowl of water while it is still in its pot. Remove later and let extra water drain. Finally, remove the pot and dry the root ball if a plant wilts and the compost is unusually wet.
Leaves Fall Off
Sometimes leaves fall off because of conditions like dry or wet soil, pests and diseases, and cultural influences, such as a sharp drop in temperature. Reposition the plant and keep it away from drafts in a consistent, warm environment.
Excessive watering or insufficient feeding causes leaves to turn yellow and gradually wilt.
Flower Buds Fall Off
The plant may lose flower buds if it is exposed to a draft, a dry environment, or a sudden chill. If a plant is knocked over severely, buds frequently fall off.
Damaged Leaf Surfaces
Lack of water may cause the edges of leaves to become crisp and brown, but water splashing on the surface of leaves, especially soft and hairy ones, causes straw-colored patches that are then burned by direct sunlight.
Using Chemicals to Combat Houseplant Problems
Insecticides and fungicides can be applied to plants in a variety of ways.
The most popular technique is spraying. You can use a plastic bag to make a sealed-off area for controlling the spray.
It’s common to dust, and a puffer-style applicator is sold for this purpose.
You can bury insecticidal sticks in the compost. The plant’s roots absorb the chemical, making the entire plant poisonous to insects.
Tips for Health While Using Houseplant Chemicals
- Never use stronger or weaker solutions; always adhere to the manufacturer’s instructions.
- Never combine two different chemicals unless instructed to do so.
- Verify that the chemical is safe when spraying plants; some plants are sensitive to certain substances.
- Keep chemicals out of reach of family pets and children.
- If animals are present, refrain from spraying; chemical sprays are particularly harmful to fish and birds.
- Never let children or animals lick or chew on sprayed plants.
- Apply only chemicals made for indoor use. This will be stated on the label, but consult your local nursery or garden center if you’re unsure.
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Davin is a jack-of-all-trades but has professional training and experience in various home and garden subjects. He leans on other experts when needed and edits and fact-checks all articles.