Agriculture Reference
In-Depth Information
• Control storage conditions, bearing in mind the desired
final tuber quantity and quality and the condition of the
tuber on store entry.
• Be vigilant in surveillance for potential problems
• Identify problems quickly and decide on appropriate
solutions
Within the UK almost 100% of potato seed storage is
box storage with traceability being the major issue. This
system also provides the potential to store more than one
variety in the same store. In a recent survey in the UK on
seed storage (BPC 2005) the most common size of seed
store was 1000-1250 tonnes (approximately 25% of stores)
with a typical loading capacity of 100-200 tonnes per day
(approximately 60% of stores) giving a time to fill the store
of eight days or less (again approximately 60% of stores).
After storage nearly 80% of stores were warmed before
grading.
The following websites provide further useful information
on potato pests and diseases and their control:
http://vric.ucdavis.edu/veginfo/commodity/potato/potato_
storage_disease.pdf
http://info.ag.uidaho.edu/pdf/CIS/CIS1131.pdf
http://www.gov.mb.ca/agriculture/crops/potatoes/bda04s
07(3-4).html
http://www.potato.org.uk
Chitting stores
The object of chitting is to provide a pre-sprouted tuber
which has broken dormancy but does not have a sprout
sufficiently developed that will be easily knocked off
during handling. Thus the sprout must be short (5 mm or
less) and strong which means being green rather than white
and thin. Appropriate temperatures can achieve this chitted
seed combined with light levels to give a green sprout.
In the UK, traditionally, chitted seed in trayed boxes was
produced in greenhouses with high light levels partially
compensating for the lack of temperature control (although
frost protection has normally been used). In trials carried
out by Bishop in eastern England the temperature was
found to be in the range of 2.5-7.5°C for around 50%
of the time with the remaining 50% being above 7.5°C
(Bishop & Maunder 1980). The particular danger of green-
house chitting has been that if the ground is unsuitable for
planting at the time the seed is ready there is no way to hold
back the sprouts, which keep growing. Greenhouses are
now rarely used for this purpose in the UK.
An insulated store with lights can give better tempera-
ture control. Artificial strip lights (around 65 W/t) are hung
on the side of the potato trays and rotated on a three day
cycle. If the store is ventilated with ambient air at around
0.05 m
3
/s per tonne of seed there is the potential for
temperature control. As part of the trials mentioned above,
the temperature was maintained in the range of 2.5 −7.5°C
for around 84% of the time, but above 7.5°C for the rest of
the time (Bishop & Maunder 1980). The lights produce
heat which will normally be sufficient for any frost
protection. An alternative is to have a refrigerated store
with lights which can provide the required temperature for
the whole of the time in store.
Although producing chitted seed can be advantageous in
many cases the desired objective is to have the eyes opened
but no more, as this avoids the difficulties of handling and
means that the labour involved in placing seed in trays can
be avoided.
TUBER STORAGE
Storage of tubers for seed
When producing and storing potato seed, the objectives are
ultimately to produce a plant that provides uniform, healthy
tubers of the size required for the client market, or in some
cases the maximum yield of saleable potatoes. Although the
type and quality of seed will not ensure that these objectives
are reached, if they are not correct it will be impossible.
There are some diseases such as silver scurf which if
controlled in the seed can give a good possibility of
producing a silver scurf free crop. If the number of sprouts
are manipulated the size of the eventual tubers can be
altered. If the seed is pre-sprouted or chitted, diseases can,
in some cases, be identified. However, it must be stressed
that pre-sprouting seed does not always have a consistent
effect, for example the dry matter with cv. Maris Piper
increased in one season out of four with pre-sprouted seed
and with cv. Rooster in two out of four seasons and in the
other years there was no difference (Burke
et al
. 2005).
Therefore, the management of potato seed post-harvest and
pre-planting can make or break a seed production business.
In most cases the storage of potatoes for seed is similar
to that for ware or the fresh market but with two distinct
differences; no sprout suppressant will be used and there is
a greater tendency to use a fungicide prior to storage to
reduce the disease loading. At the later stages of storage the
crop may be graded and dressed prior to dispatch to the
client farm where it may be chitted prior to planting or at
least allowed to warm up so that when put on the planter
there is no condensation and the tubers are at a similar tem-
perature to the soil so as to avoid any temperature shock.
