The Top 5 Garlic Diseases (and How to Prevent Them Naturally)

Garlic is one of those crops most folks think you just plant, forget, and dig up when the tops fall over. That’s what I thought too — until my second year growing it, when half my harvest rotted before it ever made it to the pantry. I still remember pulling up bulbs that looked fine on the outside, only to find the base covered in white fuzz and the smell of decay hitting me before I even reached the porch.

That year taught me two things: garlic diseases don’t mess around, and you can avoid nearly all of them if you know the early signs and stick to a prevention plan.

Why Garlic Is at Risk

Garlic spends 8–9 months in the ground, which is a long time to be exposed to soilborne fungi, moisture swings, and close quarters with other plants. It’s also part of the allium family, which means many diseases can jump from onions, leeks, and shallots to your garlic patch without much trouble.

USDA Zones 3–9 can all grow garlic, but disease pressure changes with climate.

• Cool, wet regions (Pacific Northwest, Northeast) see more white rot and downy mildew.

• Warm, humid regions (Southeast, Gulf states) deal more with rust and neck rot.

• Anywhere with poor drainage can see Fusarium basal rot.

1. White Rot — Sanitation and Long-Term Rotation

How to spot it: Yellowing leaves starting from the tips, white fluffy growth around the base of the bulb, and black specks (sclerotia) in the soil. Once you have it, it can live in the ground for decades.

Prevention Steps:

1. If your soil tests positive or you’ve had an outbreak, rotate garlic and onions out of that bed for 8+ years.

2. Pull and destroy infected plants immediately — don’t compost.

3. Sanitize tools with a bleach solution before using them in another bed.

4. In warm, sunny climates, consider solarizing the soil between crops to reduce spore load.

Pro Tip: White rot spores spread on dirt stuck to boots and tools. Treat your garden like a biosecurity zone after an outbreak.

2. Downy Mildew — Spacing, Airflow, and Organic Sprays

How to spot it: Pale green blotches on the upper side of leaves, with a purplish-grey mold underneath, especially in cool, damp weather.

Prevention Steps:

1. Space garlic 6–8 inches apart for airflow.

2. Water early in the morning so leaves dry quickly.

3. Mulch lightly — too much traps humidity.

4. Use OMRI-listed copper or biological fungicides preventatively during wet spells.

3. Rust — Resistant Varieties and Sulfur Dust

How to spot it: Bright orange pustules scattered along the leaves. It usually shows up in mid-to-late spring, right when the bulbs are sizing up.

Prevention Steps:

1. Plant rust-resistant varieties like ‘Inchelium Red’ or ‘Thermidrome’ if rust is common in your area.

2. Apply sulfur dust preventatively when humidity is high and temps are 55–75°F.

3. Remove badly infected leaves to slow spread — but leave enough foliage for the bulb to finish.

4. Fusarium Basal Rot — Soil Drainage Solutions

How to spot it: Bulbs with brown, rotted basal plates (the flat bottom where roots emerge) and plants that yellow prematurely.

Prevention Steps:

1. Grow garlic in raised beds or sandy loam with excellent drainage.

2. Rotate away from alliums for at least 4 years.

3. Avoid injuring bulbs during weeding or harvest — wounds are open invitations for Fusarium.

5. Botrytis Neck Rot — Proper Curing and Storage Methods

How to spot it: Soft, sunken areas around the neck during storage, often with gray mold. Usually appears after harvest if bulbs were not cured properly.

Prevention Steps:

1. Cure garlic in a warm, dry, shaded spot with steady airflow for 2–3 weeks.

2. Store only fully dry, undamaged bulbs.

3. Keep long-term storage temps 32–40°F with low humidity.

Grandma’s Tip

“If your garlic’s crowded, it’s like putting sick kids in the same bed — they’ll all catch it.”

Printable Tool

Garlic Disease Prevention Checklist — Planting through storage:

• Rotate beds (4–8 years depending on disease history)

• Space plants 6–8 inches apart

• Water early, allow leaves to dry

• Sanitize tools if disease is suspected

• Cure and store properly

A Principle Worth Remembering

Disease prevention is a form of stewardship — guarding what you’ve worked hard to grow. As Proverbs 27:23 says, “Be diligent to know the state of your flocks, and attend to your herds.” If you’re attentive in the field, you’ll have more to bring to the table.

Next Step

Before your next planting season, walk through the checklist and see where your setup might leave garlic vulnerable. Small changes now can mean a full pantry later. And if you’ve got fellow gardeners nearby, share this guide — a little prevention spreads faster than any fungus.