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USDA-NIFA Research Project

Project Title: Biological and Economic Impacts of Emerging Tuber Necrotic Viruses and the Development of Comprehensive and Sustainable Management Practices

This project is funded by the USDA NIFA Specialty Crop Research Initiative (SCRI) award 2014-51181-22373 in collaboration with the Tri-State Potato Commission, the Oregon Potato Commission, Simplot and seed certification agencies in CO, ID, ME, MI, MN, ND and WA. This project is a continuation of efforts on a previous award 2009-51181-05894 which focused on issues relevant to PVY. View information on the multi-disciplinary project team.

Project Overview, Objectives and Expected Outcomes

Over the past decade, Potato virus Y (PVY), Potato mop-top virus (PMTV) and Tobacco rattle virus (TRV) have emerged as serious disease problems in seed potato production areas in the USA.

Current practices in potato seed certification depend on visual assessment of virus symptoms in the growing crop. Seed certification inspectors visit seed production and post-harvest testing fields at key periods during the growing season and identify infected plants based on observation of characteristic foliar symptoms.

If there are no foliar symptoms inspections fail to identify infected plants. In the past, PVY was effectively managed by seed potato inspection programs because the virus caused readily identifiable foliar symptoms. Today, popular potato varieties support PVY infection without showing symptoms. And PVY ‘strains’ or types have emerged that cause tuber disease. Many of these new strains cause mild symptoms above-ground, yet they are more damaging to tubers below-ground. PMTV and TRV rarely cause foliar symptoms. The damage from infection is primarily restricted to the tubers.

Inaccurate field inspections and improper diagnosis can also contribute to unnecessary trade restrictions. PVY, PMTV and TRV pose a significant threat to the potato industry. Necrotic strains of PVY and PMTV are regulated by some international trading partners and do impact interstate and international seed and ware potato trade.

Research Objectives

A new approach is needed if we are going to stop the spread of PVY, PMTV and TRV. The objectives of this project are as follows:

Assist seed certification agencies to improve their ability to detect, monitor and regulate seed stocks.

  • Development of serological and/or PCR-based diagnostics to determine the virus species and strain from foliar and tuber tissue as well as populations of nematode and protozoan vectors of TRV and PMTV, respectively, from soil.
  • Scientific and economic feasibility of alternatives to the current post-harvest field grow-out to determine virus levels in seed potatoes.
  • Inspector training for field detection of tuber necrotic viruses and GPS based applications for recording and archiving data on crop quality and disease incidence

Assist breeding programs to develop improved methods to identify and characterize useful virus resistance.

  • Expression of tuber necrosis induced by PVY, PMTV and TRV under different environmental conditions in popular potato varieties representing all production classes.
  • Resistance gene markers using potato populations segregating for various types of resistance to virus infection/replication and tuber symptom development.

Assist growers with cost effective risk management tools to manage virus impacts on the farm.

  • Risk and economic analyses of virus incidence in the seed and to tolerance limits imposed by the State National Harmonization Standards.
  • Elements of risk in the landscape that contribute to vector abundance, timing and distribution of vector movement, and PVY disease development and spread in susceptible potato.
  • Virus strain and potato variety interact to impact the quality of tubers.

A large, multidisciplinary team has been assembled to address the problem from all sides. Thirty university and USDA scientists including plant pathologists, plant breeders, molecular biologists, entomologists, ecologists, horticulturalists, economists and extension specialists are working in close collaboration with seed certifiers and growers in 11 seed producing states to meet this challenge by developing a comprehensive and sustainable management plan.

An evolving national management plan, sanctioned by the industry, provides guidelines aimed at reducing overall incidence of PVY and limit the introduction of necrotic strains. Several project scientists have served as advisors for the US-Canada Management Plan for Viruses That Cause Tuber Necrosis in Potato Tubers , signed into effect in April 2006. The plan has facilitated the trade of potatoes within and between the US and Canada, but has little to manage the spread of virus. Continued research has led to proposed changes that are being discussed by the regulatory agencies. Similar efforts are being pursued with Mexico through the North American Plant Protection Organization (NAPPO).

To ensure our work addresses relevant issues and meets industry needs, we meet annually with growers, industry representatives, seed certification officials, and federal regulatory officials. There we share research findings and potential recommendations to modify the current management plan and receive input from the industry on their research needs.

A cost-benefit analysis will be conducted for each of the scientific recommendations to assist the industry and regulatory agencies in deciding acceptance of any proposed changes to the national plans. Cost-benefit analyses also can assist state certification and regulatory agencies and individual growers in determining whether to adopt individual practices.

Expected Outcomes:

Short term:

  • Determine genetic variability and geographic distribution of viruses and vectors
  • Develop and maintain virus and vector collections
  • Develop and maintain a centralized website/blog to disseminate information to and receive feedback from stakeholders and the public
  • Develop tools allowing easier access to a more comprehensive GIS-associated database of seed potato certification inspection data
  • Develop potato populations segregating for various types of virus resistance

Medium term:

  • Improve pathogen diagnostics
  • Identify useful types of host resistance that reduce virus incidence and impact
  • Develop genetic markers for virus resistance and symptom expression traits
  • Improve detection and quantification of soil-borne vector populations
  • Economic analyses of PVY tolerance limits in seed
  • Improve seed inspector training aids and applications for collecting data
  • Determine virus and vector susceptibility of widely planted potato cultivars

Long term:

  • Development of improved seed certification programs and better methods to produce disease-free seed
  • Increase national and international market opportunities by meeting trade requirements
  • Produce a safer, more consistent, and sustainable potato supply
  • Publish a Risk index forecasting model based on factors such as cultivar selection, environmental conditions, and crop management practices.
  • Evaluate project impact on the potato industry
  • Graduate students and postdocs trained in agriculture and interdisciplinary studies

 

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