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Archives
April 1-30, 2003
What's ailing our sweet
potatoes?
by Junelyn S. de
la Rosa
 Recently,
sweet potatoes (Ipomoea batatas) are gaining popularity
as health food in many countries. They are rich in beta-carotene,
Vitamin C, and antioxidants that can eliminate harmful
radicals in the body. They are also anti-inflammatory
and "antidiabetic" which means it can control
sugar levels and lower insulin resistance. In the Philippines
and other tropical countries, sweet potatoes have been
a lifesaver for centuries not only as food on the table
but as an important source of income to many farmers
and their families.
In 1989 and 1990, sweet potato viruses
wiped out the most popular variety "Bureau"
in Central Luzon. Bureau was replaced with VSP 6 or
"Super Bureau", a new variety which is high-yielding,
early maturing, with red skin and is more tolerant to
virus diseases.
Unfortunately, the same virus that attacked
the "Bureau" variety years ago is making "Super
Bureau" sick. Farmers worry that another attack
could damage the quality of sweet potatoes and significantly
lower their yields. In 1999, yield losses of more than
50% was reported due to the use of infected planting
materials.
Locally known as "camote-kulot",
infected plants become yellowish, stunted with curled
leaves. These are the same symptoms of a plant infected
with the sweet potato feathery mottle virus (SPFMV).
The International Potato Center (CIP)
reported that SFPMV alone does not lower yields severely
rather a mixed infection of SPFMV and other viruses
cause crop degeneration and yield reduction.
Scientists from Leyte State University
(LSU) theorized that there might be more than one virus
simultaneously attacking the infected plants. Research
reports from West and East Africa showed that a condition
similar to "camote-kulot" is caused by a simultaneous
infection of aphid-borne SPFMV and whitefly-borne sweet
potato chlorotic stunt virus (SPCSV).
To test their hypothesis, the scientists
identified the different viruses infecting sweet potato
in Tarlac and Bataan, the provinces that produce the
highest tonnage of sweet potato for commercial uses.
The study was conducted in May and June 2002, the dry
season planting.
Using the nitrocellulose membrane-enzyme
linked immunoabsorbent assay (NCM-ELISA) kit, the scientists
found eight kinds of viruses attacking sweet potatoes
in these areas, namely: sweet potato feathery mottle
virus (SPFMV), sweet potato mild mottle virus (SPMMV),
sweet potato latent virus (SPLV), sweet potato chlorotic
fleck virus (SPCFV), C-6 virus, sweet potato mild speckling
virus (SPMSV), sweet potato caulimo-like virus (SPCalV)
and sweet potato chlorotic stunt virus (SPCSV).
The scientists said their theory is correct-
"camote-kulot" disease of sweet potato is
due to a mixture of two or more viruses infecting the
sweet potato simultaneously such as SPFMV with other
viruses like SPMMV, C-6, SPMSV, SPCalV and SPCSV. Other
mixtures among C-6, SPMSV, SPCalV and SPCSV were also
observed.
They reported that virus infection of
sweet potatoes in Tarlac is relatively high and that
it is not safe to use planting materials from healthy-looking
plants since some viruses do not produce visible symptoms.
They recommended that farmers get their planting materials
from Bataan where sweet potato is not heavily infected
with the viruses.
Finally, the scientists recommend that
farmers should control aphids (Aphis gossypii and Myzus
persicae) and whitefly (Bemesia tabaci) especially during
the preparation of planting materials as these are vectors
of the diseases. Also, sweet potato and weeds exhibiting
similar symptoms should be eradicated from the field
or the screenhouse to prevent the spread of the disease.
Source: Sweet Potato Viruses in Central Luzon by Erlinda
A. Vasquez, Manuel K. Palomar. Edgardo E. Tulin and
Edgardo B. Barsalote of PhilRootcrops, Leyte State University,
Baybay, Leyte at Tel. No. 053-335-2626 
April 1-30 2003 Articles:
::
DA
creates open academy for Philippine agriculture
::
PCA
collaborates with international institutions to unravel
coconut genome
::
EU
tariff preferences benefit RP
::
Making
his mark
::
GIS
application in irrigation emphasized
::
BAR
joins Asia IT and C workshop
::
Philippine
agri’l engineering standards launched
::
El
Niño and coping with it
:: What’s
ailing our sweet potatoes?
::
The
world’s first GM peanut
::: More April 2003 articles :::
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