With few available treatments, a process called biofumigation is being used by some growers to manage PED. The process involves tilling mustard plants into the soil at a specific stage of growth with enough heat and moisture in the ground to induce a chemical breakdown of the plant material.
“As the mustard decomposes, it releases a chemical that reduces Verticillium wilt pathogens without adverse effects on the environment,” explains Dahu Chen, AAFC plant pathologist at the Fredericton Research and Development Centre.
As a side-effect, mustard biofumigation also delivers green compost into the soil, improving soil health. There is some evidence that the severity of PED symptoms is reduced in healthy soils.
“The disease has been around for a long time, but it is now identified to be a major factor limiting tuber yield in New Brunswick,” says Chen, who is studying the problem with colleague, AAFC researcher Bernie Zebarth.
“The pathogen can survive in the soil for a long time, even through the harshest winter conditions of eastern Canada,” explains Chen.
Chen and Zebarth are now working with industry partners, including Potatoes NB and McCain Foods Canada, to determine the effectiveness of mustard biofumigation through trials in commercial fields.
Dahu Chen, AAFC plant pathologist, examines the leaves of a potato plant for signs of disease. (Photo courtesy of AAFC)