By the HMNDP Editorial Team, independent reporting on lawn care, landscaping, and the green-industry business.
Last reviewed: June 2026
What azoxystrobin fungicide is and how it works
Azoxystrobin fungicide is a systemic, broad-spectrum strobilurin that controls a wide range of fungal diseases on crops, turf, and ornamentals. It belongs to FRAC Group 11 (QoI fungicides) and works by blocking mitochondrial respiration inside the fungus, starving fungal cells of energy. It moves into and through plant tissue, giving both preventive and limited curative activity.
The active ingredient was first commercialized by Zeneca (now Syngenta) in 1996 under the Amistar and Quadris brands. It is one of the most widely used fungicides worldwide across row crops, vegetables, fruit, golf turf, and nursery stock.
Because azoxystrobin is absorbed by plant tissue rather than sitting only on the surface, it behaves differently from a contact protectant. For a fuller comparison of how absorbed products move inside plants, see our guide to how a systemic fungicide works.
Chemical class: strobilurin (QoI) and FRAC Group 11
Azoxystrobin is a strobilurin fungicide, classified as a QoI (Quinone outside Inhibitor) and assigned to FRAC Group 11. Strobilurins are synthetic analogs of strobilurin A, a natural compound produced by the wood-rotting fungus Strobilurus tenacellus. FRAC (the Fungicide Resistance Action Committee) groups fungicides by mode of action so applicators can rotate between groups.
The “Group 11” label matters because every fungicide in that group shares the same target site. A fungus that becomes resistant to azoxystrobin is usually cross-resistant to all other Group 11 products. That single fact drives every rotation and tank-mix rule later in this guide.
Other members of Group 11 include pyraclostrobin (Headline), trifloxystrobin (Flint, Compass), fluoxastrobin, and picoxystrobin. They differ in crop fit and rainfastness but not in the basic mechanism.
Mode of action: blocking respiration at the cytochrome bc1 Qo site
Azoxystrobin inhibits mitochondrial respiration by binding at the Qo (quinone outside) site of the cytochrome bc1 complex, also called Complex III. Blocking electron transfer there stops the fungus from producing ATP, its energy currency. Spore germination is the most sensitive stage, which is why the product performs best applied before or at the very start of infection.
This is a single-site mode of action. The fungicide hits one specific protein target. Single-site chemistry is powerful but fragile: one point mutation in the fungal cytochrome b gene (most often the G143A substitution) can render the whole Group 11 useless against that population. Multi-site protectants like copper or chlorothalonil carry far lower resistance risk because they attack many targets at once.
Systemic movement: preventive and curative activity
Azoxystrobin is xylem-systemic and translaminar. After application it is taken up by leaves and roots and moves upward through the xylem, and it also crosses from the treated (upper) leaf surface to the untreated (lower) surface. This gives protection to new growth and to leaf tissue the spray did not directly contact.
The product is mainly preventive. It is strongest applied before disease shows, and it offers only limited curative reach once infection is established. It does not move downward (phloem) in significant amounts, so a soil or seed treatment protects roots and emerging tissue but will not cure an infection at the top of a mature plant.
Residual control typically runs 7 to 21 days depending on crop, disease pressure, rate, and weather. On high-pressure diseases, most labels default to a 7 to 14 day reapplication window.
Diseases azoxystrobin controls
Azoxystrobin controls both soil-borne and foliar fungal diseases across many pathogen groups. Labeled targets commonly include rusts, powdery mildew, downy mildew, anthracnose, leaf spots, blights, and damping-off. Its breadth across unrelated pathogens is what makes it a “broad-spectrum” fungicide, though it is not effective against bacteria.
- Rusts: brown rust, stripe rust in cereals; rust on beans, turf, and ornamentals.
- Powdery and downy mildews: on cucurbits, grapes, vegetables, and roses.
- Anthracnose: on turf (Colletotrichum), beans, and cucurbits.
- Leaf spots and blights: early blight (Alternaria), gray leaf spot, Septoria, and Rhizoctonia-related blights.
- Damping-off and soil-borne rots: Rhizoctonia solani, Pythium (suppression), and seedling blights.
One important limit: azoxystrobin is often weaker on established late-stage infection and on certain Oomycetes than dedicated products. For a broader menu of options by disease, our overview of choosing a fungicide for plants compares product families side by side.
Use sites: crops, turf, ornamentals, and lawns
Azoxystrobin is labeled for a wide set of use sites, including agricultural crops, golf and lawn turf, and nursery and landscape ornamentals. Exact labeled sites depend on the specific product and its EPA registration, so growers should confirm the crop or site appears on the label they hold before spraying.
| Use site | Typical targets | Common product tier |
|---|---|---|
| Row and vegetable crops | Rusts, early blight, powdery mildew, Rhizoctonia | Azoxy 2SC, Quadris |
| Fruit and grapes | Powdery/downy mildew, black rot, anthracnose | Abound, Azoxystrobin 2SC |
| Golf and lawn turf | Brown patch, dollar spot, anthracnose, Pythium, gray leaf spot | Heritage, Azoxy 2SC |
| Ornamentals and nursery | Rust, powdery mildew, leaf spot, Rhizoctonia | Heritage, Quadris |
Products and trade names that contain azoxystrobin
Azoxystrobin is sold under both brand-name and generic products. The most common trade names are Quadris and Abound (agriculture) and Heritage (turf and ornamental), all from Syngenta, plus generic labels such as Azoxy 2SC, Azoxystrobin 2SC, AzoxyStar, and Willowood Azoxy 2SC after the original patent expired. Many are EPA-registered pesticide products carrying full labeled directions.
| Product | a.i. concentration | Formulation | Primary market |
|---|---|---|---|
| Quadris | 22.9% | SC (2SC) | Ag / vegetables |
| Abound | 22.9% | SC | Fruit / grapes / veg |
| Heritage | 50% | WG (water-dispersible granule) | Turf / ornamental |
| Azoxy 2SC / Azoxystrobin 2SC | 22.9% | SC (2SC) | Generic, multi-use |
The “2SC” naming means 2 pounds of active ingredient per gallon in a suspension concentrate. That works out to about 22.9% azoxystrobin by weight, the standard for most liquid azoxystrobin products.
Formulation: what “2SC” and 22.9% mean for mixing
Most liquid azoxystrobin is a 2SC suspension concentrate: roughly 22.9% active ingredient, or 2 pounds of azoxystrobin per gallon of product. A suspension concentrate is a water-based liquid with the active ingredient suspended as fine particles, so the jug needs shaking before measuring. Heritage, by contrast, is a 50% dry granule that disperses in water.
Formulation drives the mix. A 2SC product is measured in fluid ounces; Heritage WG is measured in dry ounces or grams. Never assume a rate for one formulation transfers to the other. Always match the rate to the exact product and follow its EPA-approved label, which is the legally binding document.
Application and mixing rates: per acre and per gallon
Azoxystrobin application rates are set on the product label and vary by crop, disease, and formulation. A typical 2SC (22.9%) rate runs 6 to 15.5 fluid ounces per acre for field crops, while turf and ornamental use is more often expressed per 1,000 square feet or per gallon of spray. The label rate always governs; the numbers below are orientation, not a substitute for it.
| Scenario | Product | Representative rate | Notes |
|---|---|---|---|
| Field / row crop | Azoxy 2SC (22.9%) | 6 to 15.5 fl oz per acre | Higher end for heavy pressure |
| Turf (broad diseases) | Heritage 50WG | 0.2 to 0.4 oz per 1,000 sq ft | Longer intervals at high rate |
| Turf / lawn spray | Azoxy 2SC | ~0.38 to 0.77 fl oz per 1,000 sq ft | Confirm on your label |
| Garden / ornamental spot | Azoxy 2SC | Follow the smallest labeled rate, often near 0.2 to 0.4 fl oz per gallon | Only if your label lists per-gallon use |
Handheld and backpack sprayers price rates by gallon, not acre. To convert a per-acre rate, decide your spray volume per acre (often 20 to 40 gallons for turf) and divide. Example: a 12 fl oz per acre rate at 30 gallons of finished spray per acre equals 0.4 fl oz of product per gallon of water. Then measure only the water you will actually spray for your area so you do not over-apply.
Two mixing habits protect results: shake the SC jug before pouring, and add the fungicide to a half-filled, agitating tank, then top off. This keeps the suspension even and prevents settling in the sprayer.
Preventive timing: spray before the disease shows
Azoxystrobin gives its best control when applied preventively, before or at the first sign of disease, because it is strongest against spore germination and only weakly curative. Waiting until an outbreak is visible wastes much of its advantage and pushes growers toward higher rates and repeat sprays, which raises both cost and resistance risk.
Practical timing means spraying to forecast: before a rainy stretch, before predictable brown patch weather on turf (warm nights, high humidity), or on a calendar interval during a known high-pressure window. Reapply on the labeled interval, commonly every 7 to 14 days under pressure, adjusting for rain and growth.
The gap competitors skip: Group 11 resistance management explained
Group 11 (QoI) resistance is the single biggest reason azoxystrobin programs fail, and most product pages never explain it. Because azoxystrobin hits one target site, a single fungal mutation (usually G143A in the cytochrome b gene) can wipe out control across the entire strobilurin group at once. Managing that risk is not optional fine print; it is the core of using the product well.
Resistance has already appeared in the field for pathogens like Zymoseptoria tritici (wheat), grape and cucurbit powdery mildew, and turf gray leaf spot and anthracnose. Once a population carries G143A, azoxystrobin, pyraclostrobin, and trifloxystrobin all tend to fail together. There is no “switch to another strobilurin” fallback.
Follow these rules to keep azoxystrobin working:
- Rotate FRAC groups, not just brands. Alternate with a different mode of action (for example FRAC 3 DMIs, FRAC 7 SDHIs, or a multi-site like FRAC M copper or chlorothalonil). Two Group 11 products in a row is the same as spraying azoxystrobin twice.
- Cap Group 11 applications. Most labels limit QoI sprays to roughly 1 in 3 total applications, and often no more than 2 sequential. Check your label’s resistance-management section.
- Tank-mix with a partner. Combining azoxystrobin with a multi-site protectant slows selection for resistant strains. Premixes like Quadris Top (azoxystrobin plus difenoconazole) exist for this reason.
- Spray preventively at full label rate. Cutting rates and spraying late both select faster for resistance.
- Do not rely on it alone in high-frequency programs. On turf greens and vegetables sprayed every 7 to 14 days, a strobilurin-only program burns out quickly.
The short version: azoxystrobin is a rotation partner, not a season-long standalone. Treat every Group 11 spray as a limited resource you are spending down.
PHI, REI, and safety precautions
Azoxystrobin PHI (pre-harvest interval) and REI (restricted-entry interval) are set per crop on the product label. The REI for most azoxystrobin products is 4 hours. PHI ranges widely by crop, from 0 days on some vegetables to 14 days or more on others. Always read the specific crop line on your label, because these intervals are legally enforceable.
| Interval | Typical value | What it governs |
|---|---|---|
| REI | 4 hours (most products) | Re-entry into treated area without PPE |
| PHI (vegetables) | 0 to 7 days (crop-specific) | Days from last spray to harvest |
| PHI (fruit/grapes) | Often up to 14 days | Crop-specific, check label |
| Turf/ornamental | Not food; keep off until dry | People/pet re-entry after drying |
Phytotoxicity warning: azoxystrobin is severely phytotoxic to certain apple and crabapple varieties. Spray drift or tank/sprayer contamination from azoxystrobin can injure or kill susceptible apples and crabapples. Do not spray it where drift can reach these plants, and never use a sprayer that held azoxystrobin on apples without a thorough clean-out. Some ornamentals can also show injury, so labels advise testing on a small area first.
Handling: wear gloves and eye protection, avoid inhaling spray mist, and keep the product away from streams, ponds, and storm drains. Azoxystrobin is highly toxic to fish and aquatic invertebrates, so buffer zones near water are commonly required.
Is azoxystrobin safe for lawns, gardens, people, and pets?
Used per label, azoxystrobin is registered for lawns, gardens, and ornamentals and is considered low in acute toxicity to people and pets. It is practically nontoxic to mammals and birds by the usual exposure routes. The main cautions are keeping people and pets off treated turf until the spray has dried and protecting nearby water and susceptible apple/crabapple plants.
For homeowners, the practical safety steps are simple: follow the label rate, let treated areas dry fully before letting kids or pets back on, store the concentrate out of reach, and rinse equipment away from drains. On food gardens, obey the PHI for each crop before harvesting.
Regulatory status can change and varies by country and state, so applicators should confirm current registration and any use restrictions where they spray. For ongoing green-industry and regulatory coverage, see the HMNDP news desk.
Azoxystrobin vs other Group 11 fungicides
Azoxystrobin, pyraclostrobin, and trifloxystrobin are all FRAC Group 11 strobilurins with the same single-site mode of action, but they differ in strengths and crop fit. Azoxystrobin is the broadest and most systemic; pyraclostrobin adds notable plant-health and stress-tolerance effects; trifloxystrobin is highly rainfast with strong contact and translaminar activity. Because they share a target site, they do not substitute for one another in resistance rotation.
| Active ingredient | Common brand | Standout trait | FRAC group |
|---|---|---|---|
| Azoxystrobin | Quadris, Heritage, Abound | Broadest spectrum, most xylem-systemic | 11 |
| Pyraclostrobin | Headline | Strong plant-health / greening effect | 11 |
| Trifloxystrobin | Flint, Compass | Very rainfast, strong translaminar | 11 |
The rotation trap: switching from azoxystrobin to another strobilurin is not a mode-of-action rotation. If G143A resistance is present, all three fail together. A true rotation partner is a different FRAC group entirely, such as a DMI (Group 3), an SDHI (Group 7), or a multi-site protectant.
Frequently Asked Questions
What is azoxystrobin fungicide and how does it work?
Azoxystrobin fungicide is a systemic, broad-spectrum strobilurin (FRAC Group 11) used on crops, turf, and ornamentals. It works by binding the Qo site of the cytochrome bc1 complex, blocking mitochondrial respiration so fungal cells cannot make energy. It is taken up by plant tissue and moves through the xylem, giving preventive and limited curative control, strongest against spore germination before disease establishes.
What diseases does azoxystrobin control?
Azoxystrobin controls a broad range of fungal diseases, both foliar and soil-borne. Labeled targets commonly include rusts, powdery mildew, downy mildew, anthracnose, leaf spots, blights (such as early blight), and damping-off caused by Rhizoctonia and related pathogens. It does not control bacterial diseases and is often weaker on late-stage established infections, so preventive timing matters for good results.
What is the FRAC group and mode of action of azoxystrobin?
Azoxystrobin is in FRAC Group 11, the QoI (Quinone outside Inhibitor) strobilurin class. Its mode of action is inhibiting mitochondrial respiration at the Qo site of the cytochrome bc1 complex (Complex III), stopping ATP production. This is a single-site mode of action, which makes it effective but at high risk for resistance, so FRAC rotation and tank-mixing with other groups are essential.
What are the trade names and products that contain azoxystrobin?
Common azoxystrobin products include Quadris and Abound (agriculture) and Heritage (turf and ornamental) from Syngenta, plus many generics such as Azoxy 2SC, Azoxystrobin 2SC, AzoxyStar, and Willowood Azoxy 2SC. Most liquids are 2SC suspension concentrates at about 22.9% active ingredient, while Heritage is a 50% water-dispersible granule. All are EPA-registered products with legally binding labeled directions.
What is the azoxystrobin application rate per gallon and per acre?
Rates are set by the label and vary by crop and formulation. A typical 2SC (22.9%) field rate is 6 to 15.5 fluid ounces per acre. For sprayers priced per gallon, convert using your spray volume: a 12 fl oz per acre rate at 30 gallons per acre is about 0.4 fl oz per gallon. Turf often uses roughly 0.2 to 0.77 fl oz per 1,000 square feet. Always confirm on your label.
Is azoxystrobin systemic, and how long does it last?
Yes. Azoxystrobin is xylem-systemic and translaminar: plants absorb it through leaves and roots and move it upward, and it crosses from the upper to lower leaf surface. It does not move downward (phloem) significantly. Residual control typically lasts 7 to 21 days depending on crop, disease pressure, rate, and weather, with most high-pressure labels defaulting to a 7 to 14 day reapplication interval.
How do you prevent azoxystrobin resistance (Group 11 rotation)?
Rotate by FRAC group, not brand: alternate azoxystrobin with a different mode of action (Group 3 DMI, Group 7 SDHI, or a multi-site like copper or chlorothalonil). Do not follow one strobilurin with another, since Group 11 shares one target site and a single G143A mutation defeats all of them. Cap QoI sprays (often 1 in 3 applications), tank-mix with a multi-site partner, and always spray preventively at full rate.
Is azoxystrobin safe for lawns, gardens, and around people or pets?
Applied per label, azoxystrobin is registered for lawns, gardens, and ornamentals and is low in acute toxicity to people, pets, and mammals. Keep people and pets off treated turf until it dries, obey each crop’s pre-harvest interval before eating garden produce, and protect nearby water since it is highly toxic to fish. It is also phytotoxic to certain apple and crabapple varieties, so avoid drift and clean sprayers thoroughly.