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Plant diseases

Winter 2016

Saving citrus from a sour end

An invader is sweeping like fire through the citrus groves of Florida. The Candidatus Liberibacter asiaticus bacterium causes citrus greening, a disease that block trees’ nutrient and water channels and prevents fruit from ripening.

“It’s like choking the tree from the inside out,” says David Gang, a Washington State University molecular biologist and biochemist who is collaborating with a large, multi-institution, interdisciplinary team to combat the disease. If left unaddressed, the entire U.S. citrus industry could be wiped out and, as Florida Senator Bill Nelson said a few years ago, “We’ll end up paying $5 for an orange—and it’ll have to be one imported from … » More …

Staff photoillustration/Wikimedia
Summer 2013

Why aren’t plants more sick than they are?

Why are plants immune to most of the diseases surrounding them in the environment? Lee Hadwiger, Washington State University professor of plant pathology, has been wrestling with this question most of his career.

Were it not for a commonplace but mysterious trait called non-host resistance (NHR), plants would be constantly attacked by fungi, bacteria, and other pathogens swarming in the air, soil, and bodies. For the most part, plants are immune to those challenges because NHR gives them their robust and durable immunity to the myriad pathogens challenging them.

In the January issue of Phytopathology, Hadwiger and his colleague, USDA Agricultural Research Service plant pathologist … » More …

Lindsay du Toit with spinach
Spring 2013

Spinach is suspect: A pathological mystery

The case started a few years ago when a farmer approached seed pathologist Lindsey du Toit at WSU Mount Vernon wondering what was damaging his spinach seed crop out in the field. He had planted on clean ground that hadn’t had spinach before. He wondered if maybe the stock seed had a problem.

“It didn’t make sense,” says du Toit, explaining that what happened to the plants didn’t fit with the known diseases. At the time, du Toit and one of her graduate students were looking at fungal pathogens in the seeds of spinach plants. About 75 percent of the spinach seed grown in … » More …