Specs are compiled from manufacturer listings and verified buyer reviews and can change over time — please confirm the key details on the product page before buying.
Mums are supposed to explode with color in the fall, not turn brown and mushy from a fungal infection. But powdery mildew, rust, and blight don’t care about your plans—they show up anyway. The right spray stops the damage before it steals your display, and this guide gives you the exact picks that work, not the ones that just sit on the shelf.
I’m Rikta — the founder and writer behind Lawn Gear Lab. This guide is built by comparing the manufacturers’ published specifications and the patterns across verified customer reviews, so you get each pick’s real strengths and trade-offs instead of marketing spin.
Whether you grow cushion mums along the walkway or a full bed of football-size blooms, the right choice keeps the foliage clean and the flowers coming. This is your straight-to-the-point guide on the very best fungicide for mums.
Our Picks at a Glance
How To Choose The Best Fungicide For Mums
Picking a fungicide for your mums means deciding how you want to fight the problem: stop it before it starts, or hit an active infection hard. The active ingredient and the form (liquid concentrate vs. ready-to-spray) decide which job the product does best.
Active Ingredients: Copper, Sulfur, or Systemic
Liquid Concentrate vs. Ready-to-Spray
A liquid concentrate is the most economical route for a large garden. You mix a small amount of product with water, getting dozens of treatments from one bottle. Ready-to-spray (RTS) bottles attach directly to your garden hose, so you skip the measuring and mixing. The trade-off: RTS bottles are more convenient for a quick treatment of a few plants, but they cost more per application and you can’t adjust the strength.
OMRI Listing and Organic Gardening
If you avoid synthetic chemicals, look for an OMRI Listed label. This means the product meets the standards for certified organic production. Both copper and sulfur fungicides are naturally occurring minerals, and many of them carry the organic designation. That matters if you plan to use the same spray on vegetables or herbs growing near your mums.
Quick Comparison
| Model | Best For | Active Ingredient | Item Form | Size | Amazon |
|---|---|---|---|---|---|
| Southern Ag Liquid Copper★ Best Overall | General Prevention | Copper Ammonium Complex | Liquid | 1 Gallon | Amazon |
| Fertilome F-StopBest Value | Spot Treatment | Myclobutanil | Liquid | 32 oz | Amazon |
| Fertilome Fungicide 5 | Organic Gardens | — | Oil | 32 oz | Amazon |
| Bonide Sulfur | Powdery Mildew | Sulfur | Spray | 4 lbs | Amazon |
| Bonide Copper 4E | Potent Prevention | Copper | Liquid | 16 oz | Amazon |
| Atticus Gunner | Systemic Control | Propiconazole | Liquid | 1 Gallon | Amazon |
| Atticus Stergo MX | Root Rot | Mefenoxam | Liquid | 32 oz | Amazon |
In‑Depth Reviews
1. Southern Ag Liquid Copper Fungicide, 1 Gallon
Our pick — over 4.5★ from 400+ verified ratings; the strongest balance of quality and price.
The gallon jug that covers a whole bed and then some.
This is the top pick because it does two things most fungicides cannot touch: it knocks out both bacteria and fungi, and it comes in a 1-gallon jug that weighs 9 pounds. For a mum bed with powdery mildew or leaf spot, this is the closest thing to a one-bottle solution. Buyers report that it “got rid of poison mushrooms in my dog yard” and that it is “100% organic, nontoxic to animals/humans,” a huge relief when you want to protect pups and plants at the same time. The copper ammonium complex (31.4% strength with 8% metallic copper equivalent) coats the leaves to create a protective blanket. Effectiveness gets the most praise by far among owners, and the crowd—with a top rating and hundreds of reviews—backs it up.
At 9 pounds per gallon, you feel the weight when you lift it. That is because it is a concentrate — you dilute it yourself. This does mean you need a sprayer and a measuring cup. But a single gallon of concentrate makes far more spray than any ready-to-use bottle, which is why the value for money draws the second-highest count of positive mentions. Your mums get coverage from the first spray of spring right through the rainy fall weeks.
Best For
- Controls both bacterial and fungal diseases — a rare double threat for mums
- Gallon size offers the best cost-per-application for large beds
- Reported safe for use around animals, even on a dog run
Consider This
- Requires a separate sprayer and mixing; not grab-and-go
- Heavy to handle at 9 pounds per jug
- One owner noted a 27% concentration vs. listed 31%, so check your bottle
Reach for this if: your mum bed is medium-to-large and you want a proven, multi-disease shield that won’t break the bank per treatment.
Look elsewhere if: you need a ready-to-spray bottle for a quick treatment on a single potted mum.
2. Fertilome (10765) F-Stop Lawn and Garden Fungicide RTS (32oz)
The hose-end sprayer makes it a 30-second job.
The active ingredient is myclobutanil, a systemic that enters the plant tissue and works from the inside. The 32-ounce bottle connects directly to your garden hose with an easy on-off switch. Owners mention that after treating rose bushes with black spot, “everything is healing & coming back to life.” The spray works on the upper and lower leaf surfaces — you just spray until it starts to run off.
The catch: at 2.4 pounds for a 32 oz bottle, this is on the lighter side, but the cost per ounce runs higher than a concentrate. One owner called it “a bit expensive” compared to mixing your own. However, if you have only a few mums and you want to avoid the measuring and mixing, the convenience gap is enormous — a 10-second hookup versus a 10-minute mixing session. For a single bed of mums, this is the most efficient choice.
Perfect for: preventing black spot, rust, and blights on mums without any mixing or mess. Just attach the hose and spray both sides of the leaves.
Not ideal if: you have a very large garden — the cost-per-treatment is higher than a concentrate, and an occasional bottle has been reported to arrive with sprayer issues.
3. Fertilome (16114) Fungicide 5 Ready to Spray (32 oz), OMRI Listed
An organic label that does not sacrifice punch.
If you keep an organic garden, this fungicide protects your mums without synthetic chemicals. It is OMRI Listed (approved for certified organic production), so you get no artificial ingredients. Buyers still report real results: one owner found it “works well for boxwood blight” while another said it took care of black spot on roses in 94°F heat. The formula is a ready-to-spray oil that you apply until the leaves are moist but not dripping. It controls a broad list of blights, molds, rots, spots, and mildews — exactly the threats that hit mums during a wet autumn.
The bottle is 32 fluid ounces, and it weighs exactly 32 ounces, so it is light to carry and easy to handle. The oil-based form covers leaves well, and a concentrated version is also available if you need larger batches. All five of the available reviews rate it at a perfect score, which is rare for any plant product, though the total review count is smaller than the crowd favorites above. For the organic gardener who wants a no-mix, no-synthetic solution, this is your best fit.
Grab this for: treatment of mums in an organic garden where you cannot use synthetic systemic fungicides. The OMRI label is the clincher.
Skip it for: large-scale spraying — the ready-to-spray format is pricier per gallon than a concentrate.
4. BONIDE Products 142 Sulfur Plant Fungicide, 4 lbs
A 4-pound bag that also controls bugs on the side.
Sulfur is one of the oldest fungicides around, and this Bonide product takes it a step further by also controlling thrips, mites, chiggers, and even fleas and ticks on pets. That is a lot of payload from one bag. For mums, it targets rust, leaf spot, and powdery mildew. The active ingredient is sulfur, a natural mineral that plants need for healthy growth. The fine particle size creates a thin film that sticks to leaves evenly, blocking spores. One reviewer noted it “did a great job stopping fungus on pachysandra” with just a single application, sprinkling it dry onto the ground and letting rain wash it in.
The trade-off is the mess. This is a dust formulation (though you can mix it with water and spray it), and one owner honestly called it “so freaking messy but does indeed work.” You apply it as a spray when wet-mixed or sprinkle it dry for large areas. A 4-pound bag goes a long way, which is excellent for a whole garden of mums. The mild sulfur smell fades after about an hour. If you do not mind the dusty application, this is the cheapest route to broad control.
Choose this for: organic control of both fungus and small insects on your mums and other garden plants, especially in a large area where you want one product to do double duty.
Be aware: the powder is messy to work with, and you will need a mask if you mix it dry for dusting.
5. Bonide 811 Copper 4E Fungicide 16oz (2 Pack)
A two-pack of copper concentrate with near-perfect ratings.
This Bonide copper fungicide earns a top-tier rating from owners, with effectiveness being the most-praised aspect by a wide margin. It contains copper as the active ingredient and is suitable for organic gardening. The 16-ounce bottles are a 2-pack, giving you 32 ounces total. It is labeled as great for blight and will not harm beneficial insects like bees and ladybugs — a major plus when your mums are in bloom and pollinators are visiting. Customers note it works on tomato plants to avoid fungal disease and works on Pachysandra Blight (Volutella fungus).
The versatility gets the second-most positive mentions. You can use it on everything from turf to veggies to flowers, so a single bottle covers your whole garden. It is a liquid concentrate, so you need to mix it in a sprayer. The two-pack gives you a spare bottle for next season, and owners note it “lasts for quite awhile.” A slight difference from the Southern Ag jug: this is 16 oz per bottle rather than a full gallon, so if you have a very large mum bed, you will go through it faster.
Pick this if: you want a highly-rated copper concentrate that stays effective for a long time and does not harm beneficial bugs. The two-pack is great value for a medium garden.
Skip if: you have a huge planting area — a single gallon concentrate like the Southern Ag will last longer.
6. Atticus Gunner 14.3 Fungicide (1 Gal) – Propiconazole
The same active ingredient golf-course pros use, now for your mums.
This is the heavy hitter. It contains 14.3% propiconazole, which is the same active ingredient as Banner Maxx — the professional fungicide trusted by golf courses, landscape managers, and nurseries. It targets more than 20 plant fungi, including brown patch, dollar spot, blights, powdery mildew, and rust. For mums, this means you hit the most common autumn diseases with a single spray. The MEC (microemulsion concentrate) formulation means the particles are incredibly tiny, which makes the product mix easily and stay stable in the sprayer. You can mix it once and walk away — it won’t separate and settle.
There is more to appreciate. Once the spray dries, rain or irrigation cannot wash it off easily, so you do not have to reapply after a storm. It enters the plant through root uptake and stem absorption, delivering protection that lasts up to 28 days. The low-odor solution means the only thing you notice is the result. Effectiveness is the top-mentioned aspect. One buyer mentioned it “worked to control spot anthracnose on Dogwood AFTER the disease has emerged,” proof of its curative power. It is a premium product at a mid-range price relative to the pros, which makes it the best value in the systemic category.
Grab this if: you want professional-grade, long-lasting protection for a large bed of mums and you want it to stick through rain. The 28-day residual is a standout.
Consider this: it is not OMRI listed for organic gardening, which rules it out for certified organic beds.
7. Atticus Stergo MX Mefenoxam Fungicide (32 Ounce)
The specialist for root rot when nothing else stops the wilting.
If your mums are suddenly yellowing and collapsing, the problem might be in the soil, not on the leaves. Pythium blight and Pythium damping-off are water-mold pathogens that rot roots and stems. This product contains 22% mefenoxam — the same active ingredient as Subdue Maxx used by greenhouse growers and lawn care operators. It is built specifically to stop Pythium. One owner reported it “stopped spreading in one day” on Pythium blight. That is a speed you rarely see with general-purpose fungicides. It targets root, stem, and foliar fungi in turf, ornamentals, and greenhouse plants. For mums, you apply it as a soil drench or a foliar spray and water it in within 24 hours.
The 32-ounce bottle is a concentrate. At 32 fluid ounces, it is small but powerful. Users find “a little goes a long way.” The main caution: it is the most expensive pick here, and opinions on value for money are mixed among buyers. The effectiveness gets the most praise, with quality a close second. If your mums have Pythium, you cannot afford to try a weaker product. This is the specialist for that exact problem.
Best for: treating active Pythium blight or root rot in mums that are already wilting. The one-day turnaround is a real asset.
Not for: general preventive spraying on healthy mums — reserve this for when you diagnose a soil-borne disease.
Understanding the Specs
Active Ingredient
This is the chemical that actually kills or suppresses the fungus. Copper ammonium complex (copper) and sulfur work by contact — they sit on the leaf surface and prevent spores from germinating, acting like a shield. Myclobutanil and propiconazole are systemic fungicides: the plant absorbs them, and they move through the tissue to fight an infection from the inside. Mefenoxam is a specialist for water-mold pathogens like Pythium that attack roots.
Liquid Volume / Concentrate vs. Ready-to-Use
The volume tells you how much product you get, but the real factor is whether it is a concentrate or a ready-to-spray bottle. Concentrates require you to mix a small amount with water in a sprayer. Ready-to-spray bottles (RTS) connect to a garden hose and mix automatically. An RTS bottle is faster but more expensive per gallon of mixed spray. A 1-gallon concentrate of something like Liquid Copper makes dozens of treatments, which is far more economical for a large planting of mums.
Organic (OMRI) Listing
If you garden organically, look for the OMRI Listed seal on the label. It means the product qualifies for use in certified organic production. Copper and sulfur are naturally occurring minerals, so many products containing them carry the organic designation. Systemic fungicides like propiconazole and myclobutanil are synthetic and do not qualify for organic use. Check the label before spraying if organic certification matters for your garden.
Item Form and Ease of Application
Most fungicides come as a liquid that you either pour into a sprayer or attach to a hose. Dry formulations like sulfur dust require a dusting or mixing with water. Liquids stick to leaves more evenly and are easier to measure for precise application. Dusts can blow away in wind but work well for large areas. Consider your comfort level with measuring and mixing — a ready-to-spray liquid is the simplest way to treat a few mums.
FAQ
When should I spray fungicide on mums?
Can I use a copper fungicide on mums?
What is the difference between a contact and a systemic fungicide for mums?
Will these fungicides hurt bees or other pollinators?
Is an organic fungicide as effective as a synthetic one for mums?
How often should I apply fungicide to my mums?
Can I mix fungicide with insecticide and spray at the same time?
What common mum diseases do these fungicides treat?
What does it mean when a fungicide is a “ready-to-spray” or “RTS” product?
Final Thoughts: The Verdict
For most gardeners, the best fungicide for mums is the Southern Ag Liquid Copper Fungicide because it delivers proven protection against both bacteria and fungi at a cost per treatment that is tough to top. If you want a grab-and-go option that skips the mixing entirely, grab the Fertilome F-Stop RTS. And for a stubborn leaf infection that needs a systemic punch, the Atticus Gunner is the pro-grade pick that keeps your mums clean for up to a month between sprays.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of July 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
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