It is significant that while there are some 25,000 acres of farmland in California, mostly in the San Joaquin Valley, devoted to garlic production, there are also some 14,000 acres in the valley that have been taken out of production due to the presence of a devastating and persistent soil-borne disease called white rot with the expectation that garlic may never be planted in those fields again.

“Once we find white rot, we can’t go back in, ever,” with garlic, said Robert (Bob) EhnRobert (Bob) Ehn, chief executive officer and technical manager of the California Garlic & Onion Research Advisory Board in Clovis, CA.

Every year, more acreage is added to that restrictive list. Fortunately, this year the amount of land added to the list was minimal.

“Last year, I had 19 white rot strikes,” Ehn told The Produce News. “This year, I had three.” Soil temperature conditions were hot enough this year that the disease didn’t spread much, “and we looked hard,” he said. So disease-wise, “it has been a pretty calm year.”

That is a temporary respite. What is exciting, however, is the prospect that some current research in which the board is involved could led to a way of reclaiming the land currently restricted for planting garlic.

Currently, “we are about 123 fields, almost 14,000 acres, in prime Westland ground that we just can’t go back to,” Ehn said. But it now appears possible that “if we could run a biostimulant program, then a conventional fungicide, it is possible we could go back into those fields.”

In theory, the biostimulant will render the white rot organisms susceptible to the fungicide.

Having lost the use of one synthetic product that might have done the job, the board has been working on an alternative solution with a researcher at the University of Wisconsin, who also works with the U.S. Department of Agriculture’s Agricultural Research Service.

“We are looking at the possibility of a sustainable approach for treating white rot” that would involve the use of a compost derived from “the leftovers of processing” as a biostimulant, Ehn said. “We are really in the early stages of that,” but if it works as expected, “we would be using waste from our own product” with the double benefit of adding compost to the fields and using a natural product to help bring under control the disease that has made so many of those fields unsuitable for garlic production.

If the product and the process prove effective, it will enable growers “to keep garlic and onions on the west side of the San Joaquin Valley, which is the best place in the world to grow garlic,” he said.