This presentation provides you the necessary basic details on potato wart caused by Synchytrium endobioticum

1. POTATO WART
(Synchytrium endobioticum)
Course teacher: Submitted by:
Dr. S. Parthasarathy, Ph.D. Mr. Rohith A K
Asst. Professor (Plant Pathology) 2015021109
College of Agricultural Technology
Theni

2. Occurrence and Distribution
• Synchytrium endobioticum originated in the Andean zone of South
America. It was introduced from there into the UK and from there to
continental Europe in the 1880s, and into North America (New found
land) in the 1900s. It spread widely throughout the UK and the
European continent in the early decades. The introduction of statutory
measures limited its distribution, and it has spread to a limited extent
only in other parts of the world .
• Synchytrium endobioticum occurs locally in almost all countries in
the EPPO region.
• In India it is restricted distribution.

3. Losses
• In the 1950s and 1960s numerous EPPO publications were devoted
to the disease. Once the pathogen has been introduced to a field of
potato cultivation the whole crop may be devastated and
unmarketable.
• Moreover, introduction into the soil not only renders the crop
unusable but the soil itself cannot be used for further crop
production due to the longevity of the fungus. Crops other than
potato grown in this soil cannot be used for export.
• Indirect losses arising from restrictions on the export of plants from
infested areas present a problem to European countries.

4. Hosts / Species affected
• The only cultivated host is potato, but wild species of Solanum are
also infected in Mexico. Tomato and a number of other solanaceous
plants, including Schizanthus sp., Capsicastrum nanum, Physalis
franchetii, Datura sp. and Solanum dulcamara are hosts by artificial
inoculation.
• Post-harvest, vegetative growing stage are mostly affecting period

5. Symptoms
Aerial symptoms
 Aerial symptoms are not usually apparent.
 Reduction in vigor.
 Warts can be found in severe attacks on the upper stem, leaf and
flower.
 Leaf stalks may develop hypertrophic 'wings'. Above-ground galls
are green to brown, turning black at maturity, and later decaying.

6. Subterranean symptoms
 Galls vary in shape but are mostly spherical, with corrugated
surfaces, and range from pea-size to fist-size <1 cm to >8 cm
diam.).
 Ground galls are white to brown, turning black as they decay. These
galls appear at stem bases, stolon tips and tuber eyes. At harvest,
galls may desiccate or decay.
 Tubers may be disfigured or completely replaced by galls. Tuber
galls may develop after harvest, in storage.

7. Stages of Potato wart on tuber

8. Wart attack on tubers and stolons

9. Symptoms on stem base

10. Leaf symptoms

11. Pathogen - Synchytrium endobioticum
• Synchytrium endobioticum is an obligate, holocarpic
• Endobiotic parasite.
• It is long-cycled chytrid which does not produce hyphae but a thallus
comprised of sporangia.
• Two forms of sporangia exist, so-called summer and winter sporangia
(resting spores), which contain 200-300 motile zoospores.
• Synchytrium endobioticum develops no mycelium.
• Sporangia are clustered into thin-walled soruses. The motile life
stage, zoospore is about 0.5 µm in diameter and has one
posterior flagellum.

13. Taxonomy
Kingdom: Fungi
Division: Chytridiomycota
Class: Chytridiomycetes
Order: Synchytriales
Family: Synchytriaceae
Genus: Synchytrium
Species: S. endobioticum
Binomial name
Synchytrium endobioticum (Schilb.) Percival 1909

14. Life Cycle

15. Disease Cycle
• In the spring, resting sporangia in decaying warts and soil germinate to
release haploid (uninucleate) zoospores .
• These zoospores migrate in soil water for a limited distance (50 mm or
less) to arrive at epidermal cells of meristematic tissues of growing points,
buds, stolon tips, or young leaf primordia.
• Zoospores are short-lived and must encyst and infect susceptible host tissue
within 1-2 hr after their formation.
• After infection by zoospores, potato host cells enlarge and haploid sori
form inside the host cells while neighboring host cells begin to proliferate,
resulting in the characteristic warty galls and the increased presence of the
meristematic tissue that provides new infection courts for the fungus.

16. • Each sorus contains one to nine summer sporangia, which in turn
germinate to produce new haploid zoospores which reinfect
susceptible tissue (i.e., a secondary disease cycle).
• These rapidly repeating secondary disease cycles ultimately result in
an extensive invasion of host cells and rapid onset of gall formation.
• Young galls are a nutrient sink and expand rapidly at the expense of
other plant tissue. For example, gall volume has been observed to
increase more than 1,800-fold in 16 days

17. Spread and Survival
• Spread in soil by zoospores is limited (50 mm or less) to the infection zones of
the plant.
• Soil water can carry zoospores downstream, although the lifespan of a
released zoospore is 1-2 hours.
• Earthworms can move resting spores short distances. Wind is an active
dispersal agent in regions of strong dry summer winds.
• Local dispersal has been shown in resting spores in soil attached to vehicles
and contaminated manure.
• Long-range dispersal by tuber-movement, especially in international trade,
attached soil and plants presents problems of control. The disease is essentially
social, dependent on commercial crop and soil movement.

18. Favorable conditions
• The most favorable conditions for its development are warm
temperatures (but not over 20 °C) with enough humidity.
• Winter sporangia can remain viable for up to 20–30 years. It can
survive at depths of 50 cm in the soil. Three different fungi have
been observed to parasitize the resting sporangia.

19. Integrated Disease Management (IDM)
• According to OEPP/EPPO (1990) specific quarantine requirement,
potatoes should derive from a stock free of S.endobioticum.
• Use a continuous "cover crop" to reduce movement of inoculum via
wind-blown soil.
• Amendment of infested soil with crushed crab shell (23% chitin) has
been found to suppress the disease in some situations.
• Scheduling.
• Steam sterilization of soil.
• Soil treatment – mercuric chloride and formalin
• New tolerant or resistant varieties (eg: Kufri Kanchar, Kufri sherpa,
Kufri jyothi

20. References
• http://www.apsnet.org/publications/apsnetfeatures/pages/potat
owart.aspx
• https://www.plantwise.org/KnowledgeBank/Datasheet.aspx?ds
id=52315
• R.S Singh, Plant disease, 9th Edition, oxford IBH Publication
Co-Pvt. Ltd Newdelhi, page no: 463
• Ashok Aggarwal, R. S Mehrotra, Plant Pathology 3rd edition,
MC Graw Hill edu, Pvt. Ltd Chennai Page no: 541