I’m worried about my garlic.

I planted it last October and mulched it over our terribly cold winter. It came up fine, but there are symptoms that concern me. Some of the plants are turning yellow and practically fall out of the ground when I touch them.

My fear is white rot.

Sure enough, the University of California Agriculture and Natural Resources IPM confirms: “Leaves of the plants of the white rot pathogen show yellowing, leaf dieback, and wilting. Leaf decay begins at the base, with older leaves being the first to collapse. A semi-watery decay of the bulb scales results. Roots also rot, and the plant can be easily pulled from the ground.”

Ahhh! This is exactly what it’s doing. They also describe a white fuzz at the base, and at some point you can see the little black sclerotia.

Rotting Garlic

There aren’t a lot of diseases or pests that affect garlic, but the ones that do can make your garlic harvest a real disappointment. Besides the white rot, there is also basal rot. Although they have similar symptoms, the white rot tends to manifest in cooler temperatures, particularly below 75 degrees, and typically causes problems in the spring for us Northern gardeners. Basal rot likes the high temperatures.

I haven’t grown garlic or onions in this particular bed for over four years, but the white rot pathogen remains dormant for up to 20 years in a structure called a sclerotia that are about the size of a poppyseed. Actually, the fungus might not be in the soil at all. It could’ve come in on the garlic cloves that I planted, because I don’t think I used only my garlic. I planted a new variety, just to try something different. That might be my downfall this year, and I won’t be able to plant onions or garlic in this bed again.

I’m going to pull any garlic with yellowing leaves, and hope for the best for the rest of the season. As for next year, I’ll probably start with new seed from a reliable source, and I might even heat treat them. If you dip the garlic cloves in 115-degree water, it will kill the bulk of the fungus (if present). Hot water also helps minimize nematode issues, as well. But be careful because if you have the water too hot, it’ll harm your garlic, too!

Besides white and basal rot, there are a number of fungi that may attack garlic. Botrytis rot (gray mold) and downy mildew are other fungi that might be problematic, although thankfully there is something you can do about them after the infection.

How to Treat Garlic Rot

A product that is effective on many of these issues is Serenade, with the main ingredient of Bacillus subtillis. It’s a foliar spray you can start before you have a problem (if you’re prone to fungal diseases), or as soon as the first symptoms appear. Spray every week (or more frequently if the disease is very severe) up to the day you’re going to harvest. I don’t believe it’s very effective with white rot or basal rot, but it does work with the Botrytis rot and downy mildew. Plus, it’ll knock out a lot of fungal diseases on other plants.

I sure hope everyone else is having a good year with their garlic. It’s one of my absolutely favorite crops, and while it’s typically easy to grow, once and a while there are a few bumps along the way.