Species complex
i) Golden cyst nematode- Globodera rostochiensis (Wollenweber) Behrens
ii) White potato cyst nematode- G. pallida (Stone)
Behrens
Distribution:
PCNs are native to Andes mountain of South America and presently prevalent
in about 60 countries. The yellow cyst nematode, G. rostochiensis is
relatively wide spread (being reported from 58 countries) while G. pallida
is less prevalent (present only in about 27 countries). In India, PCNs are found
in Ootacamund, Nillgiris hills and Kodaikanal hills. There is domestic
quarantine against potato cyst nematode and therefore PCNs are restricted to
Nillgiris and Kodaikanal hills in India.
Host range:
Potato is the most important host for both G. pallida and G.
rostochiensis. However, potato cyst nematodes (PCN) also attack other
solanaceous plants, e.g. tomato, eggplant and, occasionally, some solanaceous
weeds such as bittersweet (Solanum dulcamara). Each species of PCN has
several pathotypes; these differ in their ability to multiply on different
potato cultivars.
Nature of
damage and symptoms:
PCN
infestation initially appears in patches and then spreads in the entire fields
within 4-5 years through irrigation water, wind, agricultural implements,
humus and movement of seed material grown from the infested fields. 
The
infested plants lose vigour, become sickly in appearance with stunted growth,
dull appearance and unhealthy foliage. 
Infested
plants wilt during the sunny and bright days and require more water per unit
weight compared to the healthy ones. -
Besides, they accumulate more calcium but efficiently use Nitrogen, Potassium
and phosphorus.
-
The total photosynthesis per plant is significantly reduced because of reduced
leaf area. This leads to drastic reduction in yield by 65 to 71% from summer
and autumn crops.
Identification:
-
The juveniles and adult males
of both the species are worm-like, less than 1 mm long and transparent.
- Females
are almost spherical (called cysts) and are mainly identified on the basis of
colour. The cycts of G. rostochiensis are golden in colour however
G. pallid cysts are white.
Life cycle:
-
The juveniles feed within the
roots and are not easily seen.
-
As each female matures it swells and becomes almost spherical,
bursting through the root wall. Only the head of the female remains embedded
in the root (Fig )
-
The swollen female is shiny, spherical, less than 1 mm in diameter and
initially white or cream- coloured.
The
female of G. rostochiensis passes through a prolonged golden-yellow
phase as it matures. When the female of either species dies, its body forms a
dark, reddish-brown cyst with a hard skin.-
Each cyst (cysts are the females body) usually contains 200–600 eggs. With
severe infestations, cysts may occasionally be seen on the surface of tubers.
-
At harvest, most cysts become detached from the roots and remain in the soil
(viable upto 7-10 years) as a source of infestation for future potato crops.
-
Only one life cycle occurs on each growing crop and takes from 38-48 days to
complete.
Management
-
Use of certified seed
-
Soil testing for PCN
-
Hygiene protocols for potatoes, equipment, farm workers, soil and water
-
Crop rotations: Growing non-host crops and following effective crop rotations
at least for a year with any non-solanceous vegetable such as beetroots etc.
during autumn brings down the cysts population to a great extent.
-
Variety Kufri Swarna and advanced hybrid-OS/01-516 carries resistance against
potato cyst nematodes and it also performs well even under drought conditions
in Nilgiri hills.
-
Control of non resistant self sown potatoes
- Use of Nematicides like
neemcake etc. and soil solarization.
- Furadan 3G @75 kg/ha in split
doses at the time of planting and earthing- up.
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