Authors
Kenneth E. Frost, Department of Plant Pathology, University of Wisconsin, Madison;
Russell L. Groves, Department of Entomology, University of Wisconsin, Madison; and
Amy O. Charkowski, Department of Plant Pathology, University of Wisconsin, Madison
Abstract
Long-term data sets are rare in agriculture, and the impact of plant diseases
on food production is challenging to measure, which makes it difficult to assess
the impact of policy changes or research-based disease control efforts. Despite
this challenge, it is clear that one of the largest impacts of biological
research on food security over the past century has been in production of
vegetatively propagated fruit and vegetable crops such as potato. The yield and
quality of these crops is higher in countries that have effective plant
propagation and certification systems. Of these systems, seed potato production
and certification is among the most developed. We analyzed a dataset from a
century-old seed potato certification program in Wisconsin to assess the
efficacy for potato disease control and the cost of this program compared to
other disease control and potato production costs. We found that over the past
century, certification has gradually reduced the incidence of mechanically
transmitted vascular potato pathogens that lack insect vectors to undetectable
levels, and much of this reduction occurred prior to the use of tissue culture
and the development of immunoassays. Rejection of seed lots from certification
is now rare, with Potato virus Y (PVY), a virus spread nonpersistently by
numerous, noncolonizing aphid species, and farmer errors being the main causes
of rejection. PVY level increases occurred in 2000, coincident with the first
detection of a new invasive vector, soybean aphid, in the Midwest. The increased
PVY incidence was more pronounced in varieties that exhibit mild foliar
symptoms. Starting in 2004, a decrease in PVY incidence occurred following
comprehensive science-based changes to early generation seed potato production.
The cost of the certification program has not increased in two decades, and the
fees charged are comparable to those in 1913. The cooperative nature of the seed
potato certification program has contributed to its sustainability across
generations. However, looming soilborne disease problems are not easily
addressed by certification and will likely cause significant challenges in the
future.
