The label is the law. Rates and restrictions below are taken from the product labels listed under Sources. Your product's own label governs; read it before you mix or apply. Mixing calculator · Disclaimer
- Active ingredient
- Calcium polysulfide (lime sulfur)
- Chemical class
- Inorganic sulfur compound. FRAC lists inorganic sulphur as a multi-site contact fungicide in Group M02, and IRAC lists lime sulfur in Group UN, compounds of unknown or uncertain mode of action.[3][4]
- Mode of action
- FRAC Group M02: Multi-site contact activity: inorganic (sulphur); lime sulfur labels state Group M2 fungicide and Group UN insecticide[3][2]
- Signal words
- Lime Sulfur Ultra (Tetrasul 4S5): Danger[1]
Lime Sulfur Solution: Danger[2]
No longer a home-garden product
Both current labels on this page say they are not for residential use or application to residential sites. The Classic Chemicals label adds that it may not be used in or around the household, outbuildings or noncommercial greenhouses.[1][2]
Lime Sulfur Ultra's label also bars use through any irrigation system and tells users not to use it on a crop unless local experience shows it doesn't cause damage there.[1]
Two resistance groups
The Classic Chemicals label calls lime sulfur a Group M2 fungicide and a Group UN insecticide. FRAC's M02 group covers inorganic sulphur, and IRAC lists lime sulfur by name in Group UN.[2][3][4]
Where it is used
Don't spray in freezing weather or when it is 85°F or hotter. On hot days, wait for cool evening or early morning hours.[1]
Use the mix within 3 hours and spray thoroughly without drenching leaves. Coverage matters because lime sulfur doesn't translocate.[1]
Keep it off apricots, evergreens, euonymus and rhododendrons. Don't combine it with oil on maple, beech, black walnut, Japanese walnut or flowering cherry.[1]
Spray can discolor concrete and white painted surfaces. The label suggests a mildly acidic rinse for sprayer cleanup.[1]
Products and registrations
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Lime Sulfur Ultra (Tetrasul 4S5) | Roses, dormant and delayed dormant (bud swell) | Rose scale, San Jose scale, case bearer, powdery mildew | 1–3 gal product per 100 gallons of water[1] Up to 4 dormant sprays. A fall clean-up spray at 2 to 3 gallons per 100 gallons, after leaves begin to drop, should also cover the ground. |
| Lime Sulfur Ultra (Tetrasul 4S5) | Roses, growing season | Black spot, powdery mildew, rust, red spider mites | 0.5–0.75 gal product per 100 gallons of water[1] Repeat every 10 to 15 days, up to 10 times. Pick open flowers before spraying so they don't discolor. |
| Lime Sulfur Ultra (Tetrasul 4S5) | Shade trees, ornamental shrubs, deciduous hedges and berries, dormant and delayed dormant | Anthracnose, black spot, shot hole, powdery mildew, rust, Nectria canker, maple gall, moss, lichen, San Jose and other scales | 2–3 gal product per 100 gallons of water[1] Spray 100 to 200 gallons of the dilute mix per acre, up to 4 times. Never spray evergreens, euonymus or rhododendrons. |
Safety and environmental hazards
People
Signal word DANGER: corrosive, causes irreversible eye damage, and is harmful if absorbed through the skin or swallowed. Handlers wear coveralls, chemical-resistant gloves, footwear and apron, and goggles or a face shield; workers stay out for 48 hours.[1]
Pets
Store it locked up, away from children, pets and livestock, and away from fertilizers. Never mix it with acids or phosphate fertilizers, which can release deadly, flammable hydrogen sulfide gas.[1]
Bees and pollinators
The label warns it may be toxic to plants and may harm the forage and habitat of nontarget organisms, including pollinators, next to the treated site. Follow the drift directions to protect them.[1]
Fish and water
Toxic to fish, and drift may harm aquatic organisms in nearby water. Don't apply directly to water or let equipment washwater reach it.[1]
Common questions
- Why does lime sulfur smell like rotten eggs?
- As the spray dries it releases hydrogen sulfide, the rotten-egg smell. The label says that reaction, and the sulfur crystals it forms, are what destroy the pests.[1]
- Can I use lime sulfur with horticultural oil?
- Only as directed. Dormant combination sprays are allowed, but once green tissue shows the label warns of injury, and oil and lime sulfur must be at least 21 days apart unless specified.[1]
- Can homeowners still buy lime sulfur for roses?
- The current labels reviewed here are marked not for residential use or application to residential sites, so they can't be used in home gardens.[1][2]
Sources
- U.S. EPA Pesticide Product Label System, “Tetrasul 4S5 (Lime Sulfur Ultra) label, EPA Reg. No. 71096-11 (EPA-stamped, Oct. 20, 2025).” www3.epa.gov/pesticides/chem_search/ppls/071096-00011-20251020.pdf (accessed 2026-10-06)
- U.S. EPA Pesticide Product Label System, “Lime Sulfur Solution label, EPA Reg. No. 101980-1 (EPA-stamped, July 31, 2026).” www3.epa.gov/pesticides/chem_search/ppls/101980-00001-20260731.pdf (accessed 2026-10-06). Cited for the label's statement that lime sulfur is a Group M2 fungicide and a Group UN insecticide.
- Fungicide Resistance Action Committee, “FRAC Code List 2025.” www.frac.info/media/ljsi3qrv/frac-code-list-2025.pdf (accessed 2026-10-06)
- Insecticide Resistance Action Committee, “IRAC Mode of Action Classification Scheme, Version 11.5 (Feb. 2026).” irac-online.org/documents/moa-classification/ (accessed 2026-10-06)