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
- Potassium bicarbonate
- Chemical class
- Inorganic salt. FRAC groups inorganic salts under NC, not classified, with mode of action not specified.[2][1]
- Mode of action
- FRAC Group NC: Not classified: FRAC lists inorganic salts as NC (mode of action not specified)[2]
- Signal word
- PB133 (sold as MilStop Foliar Fungicide and MilStop SP Broad Spectrum Foliar Fungicide): Caution[1]
California limits
In California the home label narrows to downy mildew and powdery mildew on a shorter crop list. That list includes roses, grapes, tomatoes, cucurbits, lettuce, spinach and several tree fruits and nuts.[1]
How it is classified
FRAC's code list puts inorganic salts in its NC group, meaning not classified, with mode of action not specified and resistance not known.[2]
Where it is used
Start spraying at the first sign of disease. Repeat every one to two weeks while weather favors disease, and shorten the interval in rainy or humid spells.[1]
It works by contact, so coat every exposed leaf and stem surface. Uneven coverage means weaker results.[1]
Mix only what you'll use that day; the label says not to store leftover spray. Adding adjuvants or other pesticides may burn susceptible plants.[1]
After harvest, a spray on remaining foliage can reduce disease that would otherwise overwinter.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| PB133 (sold as MilStop Foliar Fungicide and MilStop SP Broad Spectrum Foliar Fungicide)[1] | BioWorks, Inc. | 68539-13 | 85.0% | soluble powder | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| PB133 (sold as MilStop Foliar Fungicide and MilStop SP Broad Spectrum Foliar Fungicide) | Home ornamentals, vegetable gardens, fruit and nut trees, and lawns | Powdery mildew, black spot, downy mildew, anthracnose, Botrytis, scab, rust and leaf spots | 1–2 tbsp product per gallon of water[1] Use level tablespoons and don't exceed 2 per gallon. A gallon of spray covers about 450 sq ft. |
Safety and environmental hazards
People
Signal word CAUTION: harmful if swallowed and causes moderate eye irritation. The home label calls for goggles or safety glasses, long sleeves, long pants, shoes and socks.[1]
Pets
The hazard statement for humans and domestic animals covers swallowing and eye contact. Store it in a cool, dry place that children can't reach.[1]
Bees and pollinators
The label gives no bee or pollinator warning.[1]
Fish and water
Keep it out of storm drains, drainage ditches, gutters and surface water. Rinse your sprayer over the treated area to avoid runoff.[1]
Common questions
- How much MilStop per gallon?
- 1 to 2 level tablespoons per gallon of water, and no more. One gallon covers about 450 square feet.[1]
- Can I use potassium bicarbonate on vegetables?
- Yes. The home label lists many garden crops, including tomatoes, cucumbers, squash, peppers, lettuce, beans and strawberries.[1]
- Does it cure powdery mildew that's already there?
- The label calls it a contact fungicide and says to start at the first sign of disease. Its professional directions include a curative program for sensitive crops.[1]
Sources
- U.S. EPA Pesticide Product Label System, “PB133 (MilStop Foliar Fungicide) master label label, EPA Reg. No. 68539-13 (EPA-stamped, Oct. 20, 2021).” www3.epa.gov/pesticides/chem_search/ppls/068539-00013-20211020.pdf (accessed 2026-10-06)
- Fungicide Resistance Action Committee, “FRAC Code List 2025.” www.frac.info/media/ljsi3qrv/frac-code-list-2025.pdf (accessed 2026-10-06)