leaf blight on garlic

Asked May 20, 2013, 4:24 PM EDT

I have a patch of spanish roja garlic with what appears to be cladosporium leaf blight. The garlic is a hard neck variety and has already put out its blooms. I am concerned about the blight affecting the bulbs. The garlic is close to being ready to be dug. Is it better to dig it now or is it okay to wait a couple more weeks without using a fungus spray. I would rather dig early than loose the crop. Any help you could give would be greatly appreciated.

Yamhill County Oregon

1 Response

There are several diseases that could be affecting garlic. Go to the OSU Plant Disease Handbook http://pnwhandbooks.org/plantdisease/ , click on "hosts ", then click on "G" to get to the garlic sections. There are botrytis diseases that are fairly common now that the rain has returned. There is a garlic rust. In addition, there are other diseases that can weaken the root plate and thus reduce the vigor of the tops, often causing yellowing. Have you dug an affected bulb or two? Does it look fine below ground? If this is a commercial planting, it might be worth taking a sample to the OSU Plant Clinic on campus and getting an thorough diagnosis. Cost is $60. You could send me some pictures of the affected plant material. After you have looked over some of the problems, feel free to give me a call and we can talk about options. Weeding to improve air circulation in the canopy can reduce leaf disease problems.

Bulbing is just starting full bore and bulb will get bigger through the end of June. Remove the garlic floral stems to improve yield at this stage.

Anyway, here is my direct contact information:
Chip Bubl, Agricultural Extension Agent, Oregon State University Extension Service, Columbia County, 505 N. Columbia River Highway St. Helens, OR 97051 Phone: 503-397-3462 chip.bubl@oregonstate.edu