Fungus gnats in potted Plumeria can be a nuisance, as they thrive in moist soil conditions and can harm young plants or roots. While Telstar (or Talstar, a common insecticide with the active ingredient bifenthrin) is effective against many pests, it’s crucial to use it correctly and safely, especially for potted plants like Plumeria.

Here are some considerations and steps you should take:

1. Read the Label: Always read and follow the instructions on the insecticide label. This includes the recommended dosage, application method, and safety precautions. The label will specify if the product is safe for use on potted plants and the correct amount to use.
2. Dosage and Application: If the label indicates it’s safe for use in potted plants, ensure you use the recommended amount. A tablespoon may be too much or too little, depending on the product’s concentration and the size of your pot. Over-application can harm the plant and the environment.
3. Alternatives to Chemicals: Before resorting to chemical insecticides, consider non-chemical methods to control fungus gnats. These include:
   • Allowing the Soil to Dry: Fungus gnats thrive in moist conditions. Allowing the top layer of soil to dry out between waterings can reduce their population.
   • Yellow Sticky Traps: These can capture adult gnats and help reduce their numbers.
   • Biological Control: Beneficial nematodes or Bacillus thuringiensis subspecies israelensis (Bti) can be introduced into the soil to target the larvae without harming the plant.
4. Soil Health: Maintaining healthy soil can prevent fungus gnat infestations. Ensure good drainage and avoid overwatering. Consider using a soil mix that drains well and doesn’t retain excessive moisture.
5. Consult a Specialist: If you’re unsure about using a particular product or if the infestation is severe, consult a local extension office, a knowledgeable nursery staff, or a pest control professional. They can provide specific advice for your situation.
6. Environmental and Health Safety: Be mindful of the environmental impact and potential health risks associated with using chemical insecticides. Use them as a last resort and always in accordance with safety guidelines.

For more detailed guidance on managing pests in Plumeria, including fungus gnats, you might find resources on Plumeria-specific websites like PlumeriaCareGuide.com helpful. These sites often provide comprehensive information tailored to the unique needs of Plumeria plants.