Impact
Potato leafroll is caused by the potato leafroll virus. The severity of symptoms depends on the strain of virus, susceptibility of the cultivar, time of infection and environment. Yield may be substantially reduced in plants grown from infected tubers. Potato leafroll severity has been reduced in the San Luis Valley as a result of a comprehensive aphid suppression and monitorin program.

Potato leafroll virus symptoms.

Descriptions and Symptoms
	Leafroll is introduced by platning infected seed or by aphids carrying the virus to the field from an outside source.
	Leafroll is transmitted by several species of aphids. The green peach aphid is the primary vector in the San Luis Valley. Aphids acquire the virus after several hours of feeding adn require an incubation period befroe being able to transmit the virus to non-infected plants. Once infected, the aphid usually retains the virus for life.
	Lower leaves of plants grown from leafroll-infected seed tubers become rolled and leathery and may turn light pink or yellow.
	Infected plants usually are stunted and mor upright than healthy plants.
	Young leaves may become yellow or slightly pinkish and rolled and may stand upright in early current-season infections.
	Current-season infections that develop late in the season may cause no visible symptoms, but tubers usually become infected.
	Early season infection may reduce yield.
Integrated Management
	Plant high quality, certified seed.
	Check the weekly San Luis Valley green peach aphid monitoring reports at Agro.com.
	Control aphid populations in the field, and on other hosts.
	Rogue infected plants early in the season to control disease sources in the field.
	Consider early vine-kill when high aphid populations are present.

This material is based on work supported by the San Luis Valley Water Quality Demonstration Project Best Management Practices Advisory Committee, Colorado State University Cooperative Extension, Farm Service Agency, Natural Resources Conservation Service, and the U.S. Department of Agriculture under authorization as 1991 U.S. Department of Agriculture Water Quality Demonstration Project.