This guide explains common garlic diseases and pests, including their typical symptoms and practical control solutions. It also shares how to tell infected garlic apart, whether you find problematic plants in your own field or receive compromised bulbs purchased from other farms.

All content here is for general educational reference only. If you need an accurate, confirmed diagnosis, send plant samples to your local plant health testing laboratory for professional inspection.

You can stop garlic-specific diseases and pests before they break out, starting from your seed cloves.

The first key rule: always buy seed garlic from reliable professional suppliers. Do not use garlic from grocery stores as seed stock, even if the bulbs look perfect. Supermarket garlic may carry hidden disease pathogens without showing any surface symptoms.

1. Rotate crops across different fields every year
2. Select only full, healthy, strong garlic cloves for planting
3. Pull out and discard diseased or underdeveloped garlic plants as soon as you spot abnormal signs
4. Clean up all garlic waste in the field after harvest: collect all stalk and bulb debris to trash or incinerate. Never compost garlic plant residues, as germs can survive composting.
5. Plant suitable cover crops during off-seasons

   Well-chosen cover crops greatly improve your farm soil. Mustard is an excellent natural biofumigant — it effectively repels nematodes and raises soil organic matter. You can watch the attached 5-minute YouTube video for a full introduction to mustard cover cropping.

White Rot (caused by Sclerotium cepivorum)  1/12

“White rot” is the most devastating of all garlic diseases. It is caused by a fungus that often wipes out entire clusters of garlic plants and produces sclerotia that can remain viable in the soil for decades. When white rot incidence is low, infected plants may be “rogued” (selectively culled) and destroyed but when widespread infection occurs a complete restart in a different location and with sterilized tools is inevitable.

White rot can be difficult to differentiate from other diseases above ground. It usually affects patches of plants, rather than individuals. Growers may first notice stunted plant growth, followed by the early yellowing and death first of the outer leaves, then the rest of the leaves and the central stem. If allowed to progress, there will also be an obvious rotting of the stem above the bulb.

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Good prevention practices include:

• Annual rotation of fields and crops,

• Planting only healthy and vigorous cloves,

• Roguing (culling) diseased- or stunted-looking plants as soon as symptoms appear,

• Never leaving garlic plant debris in the field: collect all refuse and put it into the garbage or even better burn it. Never compost garlic debris.

• Cover cropping: It would be difficult to over-emphasize the value of wisely choosing cover crops to plant in fields while not in garlic. In particular, mustard is an excellent natural biofumigant that has been proven effective against nematodes, and to build soil organic matter. The 5 minute YouTube video below is a good introduction.

Garlic plants in the field with yellowing and dying leaves symptomatic of white rot.