Agriculture Reference
In-Depth Information
Fig. 8.1.
Mr Andrew Houser with the Colorado Potato Certification Service in the USA, conducting a
second field inspection for certified seed.
During final inspection, each lot's informa-
tion for the growing season is examined, and the
agency makes certain there are no problems
leading to de-certification prior to harvest. Add-
itionally, it may be necessary or required to kill
or remove the haulms (vines) chemically to con-
trol the potential for late-season virus spread by
vectors that often peak late season (NAK, 2013).
During the inspections, a set of disease tol-
erances are followed that dictate where the seed
lot fits regarding classification, and whether or
not the seed is eligible for certified status. If a lot
is deemed too high for any given tolerance, it
may be downgraded to the next appropriate clas-
sification or rejected from certification. Any lot
rejected from certification is still eligible to be
moved into the commercial potato channels for
consumption as table-stock (fresh market) or
processing potatoes.
problems (Clark and Adams, 1977; Knutson,
1998). However, variations and technologies such
as the use of polymerase chain reaction (PCR)
techniques have made detecting difficult patho-
gens and verifying strain variations in viruses
much easier. For example, Singh
et al
. (2013)
have recently shown that a real-time, reverse
transcription (RT)-PCR assay is quite effective in
detecting
Potato virus Y
(PVY) in dormant tubers.
Testing via PCR allows programs to test stocks
almost any time during the year. Many areas of
the world require soil testing prior to planting for
verifying that nematodes are not present in the
field or that powdery scab is within a reasonable
level for seed production.
It is fairly common to have foliage tested
during the growing season for various viruses
like
Potato virus X
(PVX), PVS, and PVY, as well
as other potential problems. This is true both in
the field during the growing season and in post-
harvest test plots (Sather
et al
., 2013). With the
explosion of different strains and their impact on
crops, PVY has become a worldwide concern
(Crosslin, 2013). In response, programs have
been devoting more resources to testing for the
pathogen, and have made changes in the man-
ner in which seed potatoes are produced. It is
also standard to have the progeny tubers or their
Disease testing
Disease and pathogen testing has improved dra-
matically in the past few years. The ELISA test
(enzyme-linked immunosorbent assay) is the
primary workhorse for the seed potato industry
and is used to detect viruses and bacterial
