Long Island Fungicide Guide: FRAC Groups, Rotation Schedule, and What to Buy

I spent my first two summers on Long Island watching brown patch eat circles through my lawn every July. I threw down granular DiseaseEx, crossed my fingers, and watched it happen again. The problem wasn't the product. It was the strategy. I was using one FRAC group, applying it reactively instead of preventively, and spraying with a hose-end sprayer that put down roughly the same amount of chemical as spitting into the wind. This guide is everything I wish someone had handed me before I wasted two seasons and a few hundred dollars learning the hard way.

This is not a disease identification guide. If you need help figuring out what's killing your grass, that's a different conversation. This guide assumes you want to prevent lawn disease from ever getting a foothold, and if it does show up, you want to know exactly what to spray, how much, and how often. Think of it as the fertilizer schedule equivalent for fungicide. A complete program with exact products, exact rates, and exact timing.

Why Liquid Fungicide (Not Granular)

Fungicides are one of the few lawn care categories where I strongly recommend liquid over granular. Here's why. Most turf diseases (brown patch, dollar spot, red thread) are foliar diseases. The pathogen lives on the leaf blade. To kill it or prevent it, the fungicide needs to coat the leaf surface. Granular fungicide sits on top of the grass as a pellet and has to dissolve, then redistribute onto the leaf blade through dew or irrigation. That's wildly inconsistent.

Liquid fungicide sprayed from a backpack sprayer coats every leaf blade evenly. You control the rate (fl oz per 1,000 sq ft), the water volume (2 gallons per 1,000 sq ft is the standard), and the pattern (overlapping passes for full coverage). You can also tank mix two products in the same application when needed, which you can't do with granular.

FRAC Groups Explained (No PhD Required)

FRAC stands for Fungicide Resistance Action Committee. They assign every fungicide active ingredient a group number based on how it kills fungi. Think of it like radio frequencies. Two radios tuned to the same frequency are doing the same thing. Two fungicides in the same FRAC group attack the fungus the same way, through the same biochemical pathway.

Here's why that matters: if you spray the same FRAC group over and over, the fungus population mutates to survive that specific mode of attack. You've just created a resistant strain in your own lawn. Dollar spot, the most common lawn disease on Long Island, has documented resistance to FRAC groups 1, 2, 3, and 7. That's four different chemical classes that dollar spot has learned to shrug off because people kept spraying the same product.

The 4 FRAC Groups You Need

FRAC Group 11: Azoxystrobin (Strobilurin)

Product: Azoxy 2SC Select ($48.50)
How it works: Blocks cellular energy production inside the fungus. Systemic, meaning it gets absorbed into the plant and protects from the inside out. Provides up to 28 days of protection per application.
Best against: Brown patch, summer patch, leaf spot, Pythium (at high rates), red thread.
Weakness: Not effective against dollar spot. If dollar spot is your primary problem, use FRAC 3 instead.

FRAC Group 3: Propiconazole (DMI Triazole)

Product: Propiconazole 14.3 ($69.14)
How it works: Disrupts fungal cell membrane construction. Without intact membranes, the fungus can't grow or spread. Systemic, absorbed into the plant tissue.
Best against: Dollar spot (the #1 product for this disease), brown patch, red thread, summer patch, snow mold, powdery mildew.
Note: Eagle 20EW (myclobutanil, $49.24) is another FRAC 3 option that's sometimes easier to find at box stores. Same FRAC group, so don't use both back to back.

FRAC Group 1: Thiophanate-methyl (Benzimidazole)

Product: Clearys 3336F ($71.40)
How it works: Disrupts cell division in the fungus, stopping it from reproducing. Systemic. Higher application volume than azoxy or propi (2 to 4 fl oz per 1K) so a quart doesn't last as many applications.
Best against: Dollar spot, brown patch, anthracnose, leaf spot, snow mold.
Resistance warning: Dollar spot has documented resistance to FRAC 1 in some regions. This is why you rotate, never rely on one group alone.

FRAC Group M5: Chlorothalonil (Multi-site Contact)

Product: Daconil Concentrate ($24.97)
How it works: Attacks fungi through multiple biochemical pathways simultaneously. This multi-site mode of action makes resistance development virtually impossible. Contact fungicide (stays on the leaf surface, doesn't absorb into the plant).
Best against: Brown patch, dollar spot, leaf spot, red thread, melting out. Broad spectrum coverage.
Trade-off: Because it's contact (not systemic), it washes off with rain or irrigation. Apply when you have a dry 24-hour window ahead.

FRAC Group Quick Reference

FRAC Group	Active Ingredient	Product	Key Strength
11 (Strobilurin)	Azoxystrobin	Azoxy 2SC Select	Broadest spectrum, 28-day protection
3 (DMI Triazole)	Propiconazole	Propi 14.3	Best for dollar spot + brown patch
1 (Benzimidazole)	Thiophanate-methyl	Clearys 3336F	Strong systemic, dollar spot + anthracnose
M5 (Multi-site)	Chlorothalonil	Daconil	Zero resistance risk, safety net

The 4 Diseases That Hit Long Island Hardest

Long Island's combination of summer humidity, sandy soil, and cool-season grass creates a perfect environment for a handful of specific diseases. You don't need to memorize every turf pathogen. You need to know these four.

The Complete Preventive Rotation Schedule

This is the schedule. Print it, tape it to your garage wall, set calendar reminders. Every application is a specific FRAC group at a specific rate, timed to Long Island's disease pressure windows. All rates assume liquid application in 2 gallons of water per 1,000 sq ft.

6-App Preventive Fungicide Rotation (Long Island Zone 7B)

App	Timing	FRAC	Product	Rate per 1,000 sq ft	What You're Preventing
1	Late May (GDD50 ~500)	11	Azoxy 2SC	0.38 fl oz	Dollar spot onset, summer patch (soil-borne, water in)
2	Mid-June (~3 wks later)	3	Propi 14.3	1.0 fl oz	Brown patch (nights above 60°F), dollar spot continuation
3	Early July (~3 wks later)	1	Clearys 3336F	2.0 fl oz	Peak disease pressure building, broad spectrum
4	Late July (~3 wks later)	M5	Daconil	3.0 fl oz	Peak brown patch + humidity window. Apply on a dry day.
5 (if needed)	Mid-August	11	Azoxy 2SC	0.38 fl oz	Only if disease pressure persists. Skip if lawn is clean.
6 (if needed)	Early September	3	Propi 14.3	1.0 fl oz	Only if disease pressure persists. Skip if lawn is clean.

Apps 1 through 4 are the core program. That's your minimum. Apps 5 and 6 are conditional. If your lawn looks clean going into August, skip them. If brown patch or dollar spot is still active, keep rotating. Every application uses a different FRAC group than the one before it. That's the entire point.

Exact Rates: Preventive vs. Curative

Preventive rates are lower because you're maintaining a chemical barrier before the pathogen establishes. Curative rates are higher because you're fighting an active infection. Using curative rates preventively wastes product and burns through your annual maximum faster. Using preventive rates curatively means you're under-dosing an active infection.

Preventive Application Rates (per 1,000 sq ft in 2 gal water)

Product	FRAC	Rate	Interval	Annual Max
Azoxy 2SC (22.9%)	11	0.38 fl oz	Every 28 days	7.1 fl oz/1K/year
Propi 14.3 (14.3%)	3	1.0 fl oz	Every 28 days	16 fl oz/1K/year
Clearys 3336F (41.25%)	1	2.0 fl oz	Every 14 to 28 days	Per label
Daconil 720 SFT	M5	3.0 fl oz	Every 14 to 28 days	Per label

Curative Application Rates (per 1,000 sq ft in 2 gal water)

Product	FRAC	Rate	Interval	Key Notes
Azoxy 2SC (22.9%)	11	0.77 fl oz	Every 14 days	Max 2 consecutive apps before rotating
Propi 14.3 (14.3%)	3	2.0 fl oz	Every 14 days	Tank mix with Daconil for severe brown patch
Clearys 3336F (41.25%)	1	4.0 fl oz	Every 14 days	Monitor for resistance on dollar spot
Daconil 720 SFT	M5	5.0 fl oz	Every 7 to 14 days	Contact only. Apply on dry days. No resistance risk.

The Curative Protocol (Disease Already Active)

Prevention failed, or you skipped it, or Mother Nature just decided your lawn was going to get brown patch this year. Here's what to spray and how much.

Curative Treatment by Disease

Disease	Primary Product	Rate per 1K	Interval	Key Notes
Brown Patch	Propi 14.3 (FRAC 3)	2.0 fl oz	14 days	Tank mix with Daconil for severe cases. Let spray dry before irrigating.
Dollar Spot	Propi 14.3 (FRAC 3)	2.0 fl oz	14 days	NOT azoxystrobin (poor on dollar spot). Increase your nitrogen rate slightly.
Red Thread	Propi 14.3 (FRAC 3)	1.0 fl oz	14 days	Try fertilizer first. Red thread almost always resolves with a nitrogen bump.
Summer Patch	Azoxy 2SC (FRAC 11)	0.77 fl oz	14 days	Water in after application (soil-borne). Preventive starting in April if history.
Leaf Spot / Melting Out	Clearys 3336F (FRAC 1)	4.0 fl oz	14 days	Reduce nitrogen. Raise mowing height. Improve air circulation.
Pythium Blight	Specialized (FRAC 4 or 28)	See label	7 to 10 days	Standard fungicides don't work. Needs mefenoxam or propamocarb. Pro territory.

What to Buy: The Shopping List

Budget Rotation (2 Products, ~$120 Upfront)

If you're just getting started and don't want to buy four products at once, start with the two that cover the most ground. Azoxystrobin and propiconazole together hit every major LI disease except Pythium, and they represent two different FRAC groups (11 and 3). Alternate between them every 3 to 4 weeks from late May through August. This is the "bulletproof" rotation that most lawn care communities recommend as a minimum.

Full Rotation (4 Products, ~$215)

For maximum resistance prevention and the broadest disease coverage, add FRAC 1 and FRAC M5 to your arsenal. This gives you four different modes of action and the ability to go the full season without repeating a FRAC group back to back.

The Sprayer

Alternative: FRAC 3 Box Store Option

Cultural Practices That Reduce Disease Pressure

Fungicide is one leg of the stool. If your cultural practices are inviting disease, no chemical program will save you. These are free and they make your fungicide program work harder.

When to Skip Fungicide Entirely

Not every lawn needs a preventive fungicide program. If you had zero disease issues last year, your cultural practices are solid (morning watering, proper mowing height, balanced fertilizer), and your grass type has good disease resistance (modern TTTF cultivars, for example), you may not need to spray at all. Fungicide is an insurance policy. Some lawns don't need the policy.

Start a fungicide program if: you had brown patch or dollar spot last year, you have a KBG-dominant lawn (more disease-prone than TTTF), your property has poor air circulation (fenced, shaded, or low-lying), or you water in the evening and can't change that habit. If none of those apply, skip the program and spend the money on a soil test instead.

Related Reads

If you're building out a complete lawn care program alongside your fungicide rotation, these guides cover the other critical pieces: the fertilizer schedule explains the 5-round nitrogen plan that keeps your lawn fed without creating disease-friendly conditions, the grub control guide covers the preventive insecticide program (separate from fungicide), the irrigation guide explains why morning watering is non-negotiable for disease prevention, and the month-by-month calendar shows where fungicide fits into the full annual program. For soil chemistry, the pH guide and soil test decoder are your starting points.