Myclobutanil is the homeowner's go-to systemic fungicide for fruit trees, roses, and ornamentals. It controls black spot, powdery mildew, apple scab, rust, and many other common garden diseases. Absorbed by the plant for inside-out protection.
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Classification
Triazole Fungicide (DMI / Sterol Inhibitor)
Signal Word
Caution
Mode of Action
DMI (demethylation inhibitor): blocks ergosterol synthesis in fungal cell membranes
Rose black spot, powdery mildew (roses, vegetables, ornamentals), apple scab, cedar-apple rust, brown rot (stone fruits), leaf spot diseases, anthracnose. Excellent broad-spectrum ornamental and fruit tree fungicide. Not typically used on lawns (propiconazole is preferred for turf).
🏷️ Products & Brand Names
Spectracide Immunox (most popular consumer brand), Monterey Fungi-Max, Ferti-lome F-Stop, Rally (professional), Nova (professional). Available as ready-to-spray and concentrate formulations.
⚠️ Safety & Precautions
Low acute toxicity. Wear gloves during mixing. Pre-harvest interval varies by crop — check label carefully for edible crops. Keep pets off treated ornamentals until spray has dried. Do not apply to edible crops within the specified PHI (pre-harvest interval).
⚠️ Edible crops: Always check the specific PHI (pre-harvest interval) for each crop before applying. For example, grapes typically require 14 days between last application and harvest.
Example
0.5 oz
per gallon
⚗️ Mixing Calculator
Enter your sprayer size and target rate — get the exact amount to pour. Backpack, hand sprayer, hose-end, or skid unit.
For roses: Begin applications in spring before black spot appears. Apply every 14 days during the growing season. Myclobutanil is one of the most effective rose fungicides available to homeowners.
For apple scab: Critical timing — apply at green tip stage and continue through petal fall. Once scab lesions are visible, curative activity is limited. Prevention is key.
Rain resistance: Once dried (2 hours), myclobutanil is rain-fast. It's also systemic, so it protects new growth between applications. This is a major advantage over copper-based fungicides which wash off.
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💡 Systemic fungicide. Low environmental toxicity. Some concern about endocrine disruption at high doses.
❓ Frequently Asked Questions
Q: Is myclobutanil safe for pets?
Follow the product label. Keep pets out of treated areas until completely dried (2–4 hours for sprays). Once dry, treated surfaces pose minimal risk to dogs and cats.
Q: Can I use myclobutanil indoors?
Check the specific product label — formulations vary. Baits and dusts often have indoor labeling; concentrates and granulars are typically outdoor.
Q: How long does myclobutanil last after application?
Residual varies by formulation, surface type, weather, and UV exposure. Indoor applications last longer than outdoor. Check the product label for re-application intervals.
Q: What should I do if exposed?
Remove contaminated clothing, wash skin with soap and water. For eye contact, rinse 15–20 minutes. For ingestion or severe symptoms, call Poison Control (1-800-222-1222). Have the product label available.
📋 Safety Data Sheet (SDS)
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Myclobutanil Fungicide — Safety Data Sheet
View the official SDS document for this product directly on the CDMS label database.
💡 Did you know? Myclobutanil revolutionized home rose gardening in the 1990s by making black spot control accessible to non-professional gardeners. Before systemic fungicides, controlling rose diseases required weekly contact fungicide sprays.
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Reviewed by Derek GiordanoContent reviewed by a licensed pest management professional. Last reviewed: April 2026.
