ARS Uses Chemistry to Help Control Potato Cyst Nematode


When left unchecked, the pale cyst nematode digs into the roots of potato plants to feed, obstructing nutrients and causing stunted growth, wilted leaves and other symptoms that can eventually kill the plant. Severe infestations can cause yield losses of up to 80 percent.

Currently, scientists at the Agricultural Research Service (ARS) and their colleagues are evaluating new ways of controlling Globodera pallida with the use of certain natural chemicals called "egg deposition factors."

According to Roy Navarre, a plant geneticist with the ARS, these factors for egg deposition are actually chemicals released by the roots of the potato plants and other solanaceous plants. In soil, these substances stimulate the eggs of G. pallida.

Typically, the presence of these chemicals helps ensure the survival of young nematodes. But Navarre's approach uses the chemicals to trick the eggs into hatching too early, when there are no potato plants to provide food for the nematodes or a host in which the nematodes can reproduce.

Navarre's investigations are part of a broader control effort that involves researchers from state universities, ARS laboratories, and other federal and state departments of agriculture.

G. pallida, which is native to Europe, was first detected in the eastern part of the state of Idaho in April 2006. To date, this worm has been found and confined in 17 fields, including 1,916 acres in the counties of Bingham and Bonneville in Idaho. Despite the limited geographical distribution of the worm, its presence on U.S. soil has already had an impact: the limitation or loss of access to markets in other countries to U.S. potatoes, a reduction in the value of agricultural land, regulatory restrictions, and other economic problems.

Fumigation is a key defense. However, the eggs are protected within cysts that can withstand spraying, according to Navarre, who works at the ARS Vegetable and Forage Crops Research Laboratory in Prosser, Wash.

Navarre is exploring two approaches to force the eggs to hatch without having a host: amending the soil with purified forms of the factors that hatch the eggs, and planting sticky nightshade (Solanum sisymbriifolium) as a trap since its roots produce the same chemicals that stimulate the eggs to hatch but do not provide an appropriate environment for the worm to reproduce.

Source: ARS