The SCRI Project

This website and the research and educational activities described herein are funded by a Federal Grant (#2009-51181-20176) from the USDA-NIFA-Specialty Crops Research Initiative.  The projects funded by this grant consist of a multi-state, multi-disciplinary team of scientists, economists and extension specialists, and a 12 member Advisory Board of producers, processors and industry representatives that have been assembled to address all aspects of ZC using an integrated, whole systems approach.


Primary Focus Areas

  1. Pathogen Detection, Vector/Pathogen Diversity and Disease Etiology
  2. Epidemiological Investigations and Sampling Strategies
  3. Management Strategies
  4. Breeding
  5. Economics
  6. Risk Assessment / Disease Forecasting
  7. Technology Transfer, Education & Training

Zebra Chip (ZC) is a new disease of potato that was first identified in the US in Texas in 2000, but now has spread to NE, CO, KS, NM, CA, WA, ID, ND, and Or.  ZC-infected potato plants exhibit a range of foliar symptoms, and infected tubers display necrotic flecking or streaking, which renders the tuber unmarketable.  The most significant outcome of the infection is uneven frying and subsequent burning of chips, resulting in the rejection of potatoes and leading to significant economic losses for growers.

The putative pathogen causing ZC is Candidatus Liberibacter Solanacearum, a type of bacterium which is vectored by small insect called the potato psyllid (Bactericera cockerelli).  No commercial cultivars are resistant to ZC, pesticides for psyllid control are often ineffective, and factors which impact disease epidemiology are largely unknown.  ZC has cost Texas producers millions of dollars annually, and its recent spread to other states now threatens to dramatically increase losses throughout the US.


Our goal is to develop a comprehensive, environmentally responsible disease management program that will significantly reduce ZC as an economic threat to the US potato industry.

Primary Focus Areas

To accomplish this, the Advisory Board and participating scientists identified seven Primary Focus Areas (PFAs, see more detailed descriptions below), supported by a number of sub-priorities and focused research topics, which together constitute an integrated systems approach to resolving the ZC problem.  Our team will use these seven Primary Focus Areas to address the SCRI mandated Focus Areas of Breeding, Identifying Threats from Pests and Disease, and Improving Productivity and Profitability.

  • Pathogen Detection, Vector/Pathogen Diversity and Disease Etiology
    The biology of the pathogen and vector are still poorly understood, in part because the nature of the pathogen makes it very difficult to manipulate in the laboratory.  As part of this project, we will study pathogen strain diversity, the population structure of the bacterium, and the pathogen/vector relationship.  We believe that these gaps in our knowledge hinder efforts at early detection in diseased plants, breeding for resistance in potatoes, and our ability to predict epidemic development of the disease.
  • Epidemiological Investigations and Sampling Strategies
    Certain factors, such as the population biology of the insect vector, are critical to understanding disease increase and the eventual development of effective control measures.  To gain a better understanding of disease development, we will study the following aspects of the insect vector (potato psyllid).

    • Proper sampling of the psyllid,
    • Acquisition of the pathogen by the vector,
    • A relationship between psyllid abundance and disease incidence,
    • spatial and temporal patterns of disease incidence in affected potato fields.

    The results of these studies will contribute to the goal of modeling the disease.

  • Management Strategies
    For the foreseeable future, control of ZC will rely heavily on the use of insecticides to reduce populations of the potato psyllid.  Knowledge of insecticide efficacy and the best application methods for control of potato psyllids is quite limited.  The application methods affect numerous aspects of insect mortality, repellency, and residual effects – all of which will be addressed in the project.  There are also other approaches to vector control, such as biological control and cultural practices, what will also be studied.
  • Breeding
    Genetic resistance is universally accepted as the best means of controlling any plant disease.  Developing resistance varieties of potatoes is a long term undertaking, but is essential for the sustainability of the potato industry.  Breeding for ZC resistance will be particularly challenging since all cultivars used in potato production are susceptible to the pathogen.  We will examine existing lines for variability in psyllid and ZC is needed and will be done.  In addition, exotic Solanum spp. for potential ZC and psyllid resistance may provide novel forms of resistance in potato, Solanum tuberosum.  These conventional breeding and screening methods will be combined with more progressive genetic analyses, such as microarray analysis of genes, to improve the search for ZC resistance in potato.
  • Economics
    The emphasis under this focus area is to estimate current looses to ZC and evaluate the economic feasibility of promising control measures.
  • Risk Assessment / Disease Forecasting
    We would like to develop a disease forecasting model for ZC based on sound risk assessment principles and on scientifically derived information.  A model can only be constructed through long-term sustained research on such factors as pathogen and vector biology, disease development in infected plants, and repeated control trials, as described in the sections above.
  • Technology Transfer, Education & Training
    As was mentioned in previous sections, engagement with our stakeholders is a critical part of the SCRI program.  In the case of ZC, this includes producers, processors.  Extension personnel, scientists engaged in related disease research, and policy makers.  In addition, the disease is anticipated to have an impact over a wide geographic area Therefore, it wil be important to develop and sustained outreach plan throughout the duration of the project.  This plan must include all of the traditional forms of information transfer such as fliers, fact sheets, and disease notes.  Workshops, field days, and disease symposia will also be conducted.  A Web site will be designed and implemented.  Going beyond these current forms of outreach, we are also planning on constructing a Community of Practice (CoP) on the national extension Web site (  This Web site supports a wide variety of services and resources through the CoP which are intended to maximize interaction among scientists with common purpose and engaging them with interested clientele and stakeholders.


The outcome of this united effort will be at least six identifiable deliverables:

  1. Best management practices
  2. ZC risk assessment/disease forecasting model
  3. Germplasm with demonstrated tolerance to ZC
  4. Economic models with cost/benefit analyses and best-case/worst-case scenarios
  5. Publications and educational programs dealing with all aspects of ZC
  6. Scientific data that will be useful to regulatory agencies in development of a National Pest Risk Assessment for ZC

Success in delivering these tangible products will require a high degree of communication among scientists, data sharing and integration of activities, something which the entire team has agreed to and is committed to doing.