PHI for Common Vineyard Fungicides: Quick Reference

By VitiScribe Editorial·November 8, 2025·Updated December 15, 2025

Pristine fungicide has a 0-day PHI in grapes -- that's critical information during late-season botrytis control when harvest dates are imminent. VitiScribe populates fungicide PHI automatically from label data, eliminating the risk of miscalculation near harvest. But knowing which products have short versus long PHIs before you go to the field is the kind of operational knowledge that separates well-managed spray programs from reactive ones.

This reference covers the most commonly used fungicides in US wine grape programs organized by FRAC group and disease target. PHI values are based on current federal product labels -- always confirm on the specific label before applying, as PHI can change with label amendments.

TL;DR

Quintec (quinoxyfen, FRAC Group 13) has the longest PHI among commonly used powdery mildew materials at 14 days -- plan bloom-stage applications so the 14-day window doesn't create a harvest conflict in blocks with early or variable harvest dates
Ridomil Gold (metalaxyl-M) as a soil treatment carries a 42-day PHI in grapes -- the longest of any commonly used vineyard fungicide -- which effectively limits soil applications to pre-bloom to stay within PHI for harvest
Switch 62.5WG (cyprodinil + fludioxonil), Scala SC (pyrimethanil), and Revus (mandipropamid) all carry a 7-day PHI -- in Oregon's wet autumn Pinot Noir programs where rain just before harvest drives late botrytis and downy mildew pressure, this 7-day constraint pushes growers toward 0-day PHI alternatives for the final application window
Elevate 50WDG (fenhexamid, FRAC Group 17), Miravis Prime, and Pristine all carry 0-day PHI in grapes, making them the primary late-season botrytis options when harvest dates are within the 7-day window for Switch and Scala
QoI resistance concerns apply to the pyraclostrobin component in Pristine -- if you're seeing powdery mildew breakthrough with Pristine, QoI resistance in the local population may be reducing efficacy despite the 0-day PHI flexibility
Biological products Botector (Aureobasidium pullulans) and Serenade Optimum (Bacillus subtilis) are 0-day PHI and OMRI-listed -- the appropriate late-season botrytis alternatives for organic programs where FRAC Group 17 and SDHI materials can't be used

Powdery Mildew Fungicides by FRAC Group

FRAC Group M2 (Sulfur)

Wettable sulfur (multiple brands -- Microthiol Special, Wettable Sulfur 90WP, Dusting Sulfur): 0-day PHI in grapes. Contact protectant and eradicant. Most economical powdery mildew material. Phytotoxicity risk above 90°F and below 50°F.

Lime sulfur (calcium polysulfide): 7-day PHI in grapes. Dormant and delayed dormant applications only in most programs. Eradicant activity.

FRAC Group 3 (DMI Fungicides)

Rally 40W (myclobutanil): 0-day PHI in grapes. Systemic with both protective and eradicant activity. One of the most commonly used early-season powdery mildew materials in California and Pacific Northwest.

Elite 45DF (tebuconazole): 0-day PHI in grapes. Systemic DMI with good eradicant activity.

Tebuzol 3.6F (tebuconazole): 0-day PHI in grapes.

Inspire Super (difenoconazole + cyprodinil): Check label -- 0-day PHI for most formulations but primarily a botrytis and powdery mildew combination product.

FRAC Group 7 (SDHI Fungicides)

Luna Privilege (fluopyram): 0-day PHI in grapes. Excellent systemic powdery mildew activity. Also has activity against botrytis.

Luna Sensation (fluopyram + trifloxystrobin): 0-day PHI in grapes. SDHI + QoI combination. Note QoI resistance concern.

Sercadis (fluxapyroxad): 0-day PHI in grapes. High-efficacy SDHI powdery mildew material.

Miravis Prime (adepidyn + fludioxonil): 0-day PHI in grapes. Combination SDHI product with botrytis activity from fludioxonil.

FRAC Group 11 (QoI Strobilurins)

Abound (azoxystrobin): 0-day PHI in grapes. QoI resistance widespread -- check field performance before relying on this material.

Flint Extra (trifloxystrobin): 0-day PHI in grapes. QoI resistance concerns similar to Abound.

Sovran (kresoxim-methyl): 0-day PHI in grapes.

Pristine (boscalid + pyraclostrobin): 0-day PHI in grapes. SDHI + QoI combination. The 0-day PHI and high efficacy against both powdery mildew and botrytis make it a commonly used late-season material.

FRAC Group 13 (Quinoxyfen)

Quintec (quinoxyfen): 14-day PHI in grapes. The longest PHI among commonly used powdery mildew materials. Excellent bloom-stage efficacy, but plan your timing so the 14-day PHI doesn't conflict with your harvest date.

FRAC Group U8 (Metrafenone)

Vivando (metrafenone): 0-day PHI in grapes. Unique mode of action with no cross-resistance to other major fungicide classes. Excellent powdery mildew activity.

FRAC Group 45 (Potassium Bicarbonate)

Kaligreen (potassium bicarbonate): 0-day PHI in grapes. OMRI-listed for organic programs. Contact eradicant activity.

MilStop (potassium bicarbonate): 0-day PHI in grapes. OMRI-listed.

Armicarb (potassium bicarbonate): 0-day PHI in grapes. OMRI-listed.

Botrytis Fungicides

Elevate 50WDG (fenhexamid, FRAC Group 17): 0-day PHI in grapes. Excellent botrytis efficacy. FRAC Group 17 resistance is documented in high-use vineyards.

Switch 62.5WG (cyprodinil + fludioxonil, FRAC Groups 9 + 12): 7-day PHI in grapes. One of the highest-efficacy botrytis materials. The 7-day PHI limits use very close to harvest. FRAC Group 9 (anilinopyrimidine) resistance is emerging in some regions.

Scala SC (pyrimethanil, FRAC Group 9): 7-day PHI in grapes. Similar to cyprodinil in Switch. Group 9 resistance concerns.

Vangard WG (cyprodinil, FRAC Group 9): 7-day PHI in grapes. Single-mode Group 9 botrytis material.

Miravis Prime (adepidyn + fludioxonil, FRAC Groups 7 + 12): 0-day PHI in grapes. Good late-season botrytis option with 0-day PHI.

Botector (Aureobasidium pullulans, FRAC Group BM02): 0-day PHI. Biological product. OMRI-listed for organic programs.

Serenade Optimum (Bacillus subtilis, FRAC Group BM02): 0-day PHI. Biological product. OMRI-listed. Useful for late-season organic botrytis management.

Downy Mildew Fungicides

Revus (mandipropamid, FRAC Group 40): 7-day PHI in grapes. Excellent downy mildew control. No cross-resistance to phenylamides.

Revus Top (mandipropamid + difenoconazole, FRAC Groups 40 + 3): 7-day PHI in grapes. Downy mildew + powdery mildew combination.

Presidio (fluopicolide, FRAC Group 43): 7-day PHI in grapes. Excellent downy mildew efficacy.

Zampro (ametoctradin + dimethomorph, FRAC Groups 45 + 40): 7-day PHI in grapes.

Ridomil Gold (metalaxyl-M, FRAC Group 4): 42-day PHI in grapes (as soil treatment). The longest PHI of any commonly used vineyard fungicide. Soil applications substantially limit its use timing -- most growers apply pre-bloom to stay within PHI limits for harvest. Foliar formulations have different PHI -- check label for specific use type.

Copper-based fungicides (Kocide 3000, Champion WP, Nordox): 0-day PHI in grapes for most registered formulations. OMRI-listed options available.

Key Takeaways for Late-Season Application Planning

When your harvest date is within 30 days, review every potential spray application against PHI:

Products safe within 7-14 days of harvest:

Sulfur and potassium bicarbonate (0-day PHI)
Pristine, Luna Privilege, Sercadis, Miravis Prime (0-day PHI)
Elevate, Botector, Serenade Optimum (0-day PHI)
Rally, Elite, Vivando (0-day PHI)
Most copper-based materials (0-day PHI)

Products that require planning ahead:

Quintec: apply by 14 days before target harvest date
Switch: apply by 7 days before target harvest date
Scala, Vangard: apply by 7 days before target harvest date
Revus, Presidio, Zampro: apply by 7 days before target harvest date
Ridomil Gold (soil): apply by 42 days before harvest in that block

VitiScribe calculates the harvest clearance date for every product applied to each block and displays it on the block dashboard. If your target harvest date creates a PHI conflict, the system flags the issue so you can plan accordingly. See how PHI calculator and REI tracking work in VitiScribe.

Frequently Asked Questions

What is the PHI for Pristine fungicide in vineyards?

Pristine (boscalid + pyraclostrobin) has a 0-day pre-harvest interval in grapes. This makes it one of the most flexible late-season fungicides available, with activity against both powdery mildew (through the QoI component pyraclostrobin) and botrytis (through the SDHI component boscalid). The 0-day PHI means you can apply it on the day of harvest if needed. Keep in mind that QoI resistance concerns apply to the pyraclostrobin component -- if you're seeing powdery mildew breakthrough with Pristine in your program, QoI resistance in the powdery mildew population may be reducing its efficacy.

What is the PHI for Scala fungicide in vineyards?

Scala SC (pyrimethanil, FRAC Group 9) has a 7-day pre-harvest interval in grapes. This means your last Scala application must be at least 7 days before your earliest harvest date in that block. In Oregon's wet autumn Pinot Noir programs, the 7-day PHI for Scala can be a constraint when rain events just before harvest drive you to want a botrytis application -- Switch and Scala both carry 7-day PHI. In that situation, Elevate (0-day PHI) or Miravis Prime (0-day PHI) are better alternatives for applications within the final 7-day window.

Which botrytis fungicides have the shortest PHI for use close to harvest?

Several botrytis fungicides carry a 0-day PHI in grapes: Elevate 50WDG (fenhexamid, FRAC Group 17), Miravis Prime (adepidyn + fludioxonil, FRAC Groups 7+12), Luna Privilege (fluopyram, FRAC Group 7, also active against botrytis), Botector (biological, Aureobasidium pullulans), and Serenade Optimum (biological, Bacillus subtilis). Pristine (0-day PHI) has incidental botrytis activity alongside its primary powdery mildew efficacy. The 0-day PHI materials give you maximum flexibility during the final push before harvest, but rotate FRAC groups even among 0-day PHI materials to slow resistance development.

How should vineyard managers document PHI compliance when harvest dates shift during the season?

PHI compliance depends on the actual harvest date, not the planned harvest date -- if harvest is pushed back or accelerated by weather, ripeness, or winery scheduling, the PHI status of every open spray event in that block changes accordingly. The documentation that matters is the spray record with its application date, the specific PHI for that product on grapes, and the actual harvest date. If harvest shifts after your last application, recalculate whether the PHI is still cleared for the new harvest date. VitiScribe's block harvest clearance dashboard recalculates PHI status automatically when you update a block's harvest date, so any application that would become a PHI violation under the new harvest date is flagged immediately.

What happens to PHI compliance documentation if a winery requests a different harvest date than you planned?

When a winery calls to move harvest earlier than scheduled, any spray applications made within the PHI window of the new harvest date become a potential violation -- even if they were fully compliant under the original harvest date. Document the harvest date change with a note in your block records showing the original planned date, the revised date, and the reason for the change. Review all applications in the PHI window for the revised date against each product's PHI. If any application falls inside the revised harvest PHI, contact your PCA immediately for guidance, and consider whether the situation warrants communication to the winery buyer about the residue risk. Prevention is better than response: keeping harvest clearance documents current as harvest dates change, rather than reviewing them only at the original planned date, is the practice that prevents this situation.

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Sources

California Department of Pesticide Regulation (CDPR)
Fungicide Resistance Action Committee (FRAC)
UC Cooperative Extension Viticulture
American Vineyard Foundation
Wine Institute

Get Started with VitiScribe

PHI management across multiple blocks with variable harvest dates -- and fungicide programs that mix 0-day, 7-day, and 14-day PHI materials -- creates harvest clearance calculations that are difficult to track manually and where errors directly create regulatory violations. VitiScribe pulls PHI from the label database for every product, calculates harvest clearance dates per application per block, and flags conflicts when harvest dates change after applications have been made. Try VitiScribe free and see your full PHI harvest clearance status across all active blocks today.