This is the photo I ran a couple of months ago of the wonderful garlic crop developing in the City College garden. I was looking forward to teaching about garlic next fall from the harvested bulbs. But alas, we had a late rain and the whole planting collapsed.
The cause., as far as I can tell, is garlic white rot. I realized I have been putting off reporting this sad
news, but I did take the photos, so better get it over with.
This is how the plants looked last week. Just about dead. It isn't the normal drying off that the healthy plants begin about now and finish by the end of June. The plants just collapsed in a couple of days. Generally, the infection arrives on the sets, the little bulbs you plant. I got these at the nursery, which is about all you can do to try to avoid the disease. The rain caused the fungus to grow, but it had to have been there already.
So what does the UC IPM site suggest? ( www.ipm.ucdavis.edu and follow the links to garlic and white rot). They say the fungus can live in the soil for 20 years. Great!
To prevent it, one can try dipping the cloves in water that is 115 degrees, but you have to be careful, since 120 degrees can kill them. This would be one of those operations you carry out witha little bowl, an immersable thermometer, maybe a meat thermometer, and pitchers of hot and cold water.
The other suggestion for organic gardeners, is to purchase a garlic extract product that you can apply before you plant garlic again. The fungus doesn't make spores, but tiny bits of itself harden into black dots the size of poppy seeds. If you wait a year after the infection, then treat the soil with the garlic extract, it can trick the black dots into growing, then, because there is no garlic to live on, the fungus will die.
That's a bit of a wait, but I don't see another solution on the horizon. Here is a pulled bulb of sick garlic. Not clear and clean as it should be, but covered with clinging soil, even though the soil wasn't overly wet, and you can see some of the white fungal growth.
I guess the only good news is that the disease is only of the garlic. The lettuce and arugula can't get it, or can the trial tomatoes (that are being tested for late blight resistance). And I can't catch garlic white rot.