Common Pests Of Houseplants
 | Author:
Allison Kosto, MSU Broadwater County Extension Agent
MSU Broadwater County Extension Agent |
Allison Kosto
MSU Broadwater County Extension Agent
As winter in Montana drags on, we can still find enjoyment in houseplants. Research has shown many benefits of houseplants including removing airborne contaminants, absorbing carbon dioxide, increasing oxygen levels, increasing positive feelings, reducing sound levels, and reducing stress levels. Overall, houseplants are fairly easy to care for, but there are a few common pests to watch for.
The key to minimizing pest issues is to have healthy plants. Healthy plants can withstand some pest pressure and are more likely to recover successfully. When purchasing, avoid plants with signs of insects or disease. Select plants that match your home environment and care ability. It's good practice to quarantine plants away from any others when they first come home to make sure there are no issues.
Early detection is critical for managing pests. When you water your plants, this is a good opportunity to examine your plants for anything out of the ordinary. Things to look for include changes in leaf color, spotting, webbing, dieback and leaf holes. Here are some common houseplant pests.
Spider Mites
These pests are found outdoors in Montana and can migrate indoors often coming with plants that might be moved from outdoors to indoors. They feed on plant sap and first appear as tiny white specks on the underside of the leaves. As their population increases, their webbing becomes more visible. Leaves will start browning and eventually fall off. Spider mites easily spread to other plants although they do have preferred species. Management is difficult. Washing the plants or spraying with a jet of water can dislodge the mites. This likely will need to be repeated. Spider mites are not insects so synthetic insecticides will not work unless they also contain a miticide. However, horticulture oils or insecticide soaps can be effective. The key is to get good coverage as they work by smothering the mites or insects.
Fungus Gnats
This is a small, dark colored fly that can jump and fly across the soil surface. The adults lay eggs in the soil at the base of the plant. They primarily feed on decaying organic matter in the soil and rarely cause damage to plants. However, if populations are high, they can be a nuisance. Adult gnats often congregate in windows. Alternating soil conditions is the best way to deal with fungus gnats. They prefer moist soil so make sure the soil is dry between waterings. Insecticides can also be used as a last resort.
Root Rot
Overwatering is the biggest killer of houseplants. Overwatering creates an environment for fungal root rot. Root rot is a soil-borne fungus that causes wilting and blackened mushy roots. Above the soil, plants will be yellow, brown and eventually die back. Sometimes wilting is seen. Avoiding overwatering is the best way to prevent root rot. Also, make sure to use sterile soil. Severely affected plants may need to be thrown out.
Thrips
These are also tiny insects that may require a hand lens to see. They are often recognized by their damage which is similar to spider mites. The main difference is that they cause light irregular silvery areas on the leaf surface which develop around the feeding site. Dark spots may also appear from their excrement. Thrips can be vectors for several viruses. Management is difficult because they can be resistant to insecticides. Also, the eggs are laid deep in the soil where insecticides may not reach. Pyrethroid insecticides are the most effective. Horticulture oils or insecticide soaps can be used on exposed insects.
For assistance with pest identification, control recommendations or plant care, contact MSU Extension Office in Broadwater County at 406-266-9242 or allison.kosto@montana.edu
