Is Sulfur a Good Insect Repellent?

Sulfur is an element found naturally in the environment and used in a wide array of products including insecticides. In fact, about 300 registered pesticide products contain sulfur as its active ingredient, according to the Cornell University Cooperative Extension. Sulfur insecticides are available in liquid, dust and granular form to control unwanted insects. Sulfur is also used in fungicides to control fungal pathogens that attack trees, shrubs, crops and other plants.

Sulfur is mainly used as disease control against various fungal diseases affecting plants, including rusts and mildews. However, sulfur does have some insecticidal properties and can be used to control mites, psyllids and thrips, which feed on the phloem sap found in plants. Sulfur also controls and repels chiggers, ticks, spiders and other pests in the arachnid family.

The exact application instructions for sulfur depends on the type of sulfur insecticide used, the plant it is used on and the pest you are trying to control. For example, one brand of ready-to-use sulfur dust recommends applying 1 pound per 500 square feet to control chiggers outdoors. These directions may vary and you should always follow the instructions found on the product label. Following the instructions will increase its effectiveness, help prevent damage to surrounding vegetation and decrease the chance of injury to yourself and your family.

Sulfur is not toxic to bees, birds or fish, and has a low toxicity to humans. It can, however, cause eye and skin irritation. You should always wear proper safety clothing -- such as a dust mask, rubber gloves and safety goggles -- when using sulfur. Keeping children, people and pets out of the area until it has been watered and allowed to dry will help prevent potential problems caused by the insecticide. Sulfur poses no known risks of reproductive hazards, according to the Cornell University Cooperative Extension website. However, the American Pregnancy Association warns against using organic or natural pesticides while pregnant or nursing since all chemicals have the potential to cause harm if not handled properly. It is always best to err on the side of caution and avoid any pesticides while pregnant or nursing.

Sulfur can cause plant injury if applied during dry periods of 80 degrees Fahrenheit or above. Furthermore, never apply sulfur if the plant was treated with oil pesticides within 20 to 30 days. The sulfur negatively reacts with the oil pesticide and creates phytotoxicity, which will damage the plants.