Following the lead of their medical colleagues, plant pathologists are developing vaccines that could save the beleaguered Dutch elm from a lethal fungus, and someday assist soybeans and other valuable crops as well.
The fungus invades the elms and produces spores that clog their internal water-transportation system, causing them to die of thirst. Elms actually have a natural defense: Infected trees build walls around the spores to immobilize them. Unfortunately, that response is usually too slow to save the tree. The new vaccines kick-start elms' natural immune defense system so the trees can react in time.
One vaccine--developed by ARCADIS, a Dutch engineering company--consists of spores from a benign elm fungus that evoke a preemptive reaction from the tree. Martin Hubbes, a forest pathologist at the University of Toronto, has created a competing treatment using a protein from the elm fungus. In early trials, the protein injection substantially reduced disease symptoms. "This is, in my view, the new way to go in the control of plant diseases," Hubbes says.