A breif description of the diseases of plum

1. Diseases of Plums
COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562
COURSE TEACHER
Dr. PARTHASARATHY S
Asst. Professor (Plant Pathology)
STUDENT
Mr. S. MAHI YASWANTH
ID. No. 2015021074

2. DISEASES OF PLUM
1. Brown rot : Monilinia fructicola
2. Black knot : Apiosporina morbosa (Syn. Dibotryon
morbosum, Plowrightia morbosum)
3. Bacterial canker : Pseudomonas syringae
4. Bacterial spot : Xanthomonas campestris pv. pruni
5. Plum pox : Plum pox virus

3. Brown rot
• Distribution – world wide
History
• The first published description of a brown rot fungus on decaying fruit was
in 1796.
Pathogen
• Monilinia fructicola
• M. laxa
• M. fructigena

4. Symptoms
• The brown rot fungi cause a blight of blossoms and twigs and a
soft decay of fruits.
• Infected blossoms are brown and water-soaked.
• The fungus grows down the pedicel into the stem which may
cause twig dieback.
• Diseased blossoms and fruit generally become covered with
"tufts" of brown fungal material.
• Fruit infection usually occurs near maturity.

5. Fruit rotSoft decay
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6. Systematic position
• Kingdom : Fungi
• Phylum : Ascomycota
• Class : Leotiomycetes
• Order : Helotiales
• Family : Sclerotiniaceae
• Genus : Monilinia
• Species : Monilinia fructicola, M. laxa, M. fructigena

7. Lifecycle
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8. Pathogen
• Conidia are produced on tufts of conidiophores called
sporodochia. The conidia are hyaline (colorless), lemon-
shaped, and produced in a moniloid manner.
• Ascospores produced in tubular asci produced on apothecium.
Conidia produced in moniloid
manner
Lemon shaped conidia
©bugwoodcloud.org ©media.padil.gov.au

9. • Favourable condition
Blossom infection occur at 10°C.
Wet, warm conditions also increase overwintering inoculum
available for blossom infections the following spring.
Mode of spread & survival
Sources of blossom blight inoculum are mummies, infected
peduncles, and cankers.
Conidia from these sources are disseminated by splashing or
wind-blown rain.

10. IDM
• Control is by repeated fungicide applications and sanitation.

11. Black knot
Distribution
North America, Asia, Africa, South America, European union, Canada, the
United States and Mexico
History
• Black knot disease is mainly a problem in North America where it is
indigenous.
• A record from 1979 indicated the presence of the fungus on pear.
• It was first reported as a destructive disease in Massachusetts in 1811.
• It was first described in 1821 by L. D. Schweinitz from specimens
collected in Pennsylvania.

12. Pathogen :
• Apiosporina morbosa
• Syn. Dibotryon morbosum, Plowrightia morbosum
• Anamorph: Fusicladium,
Authors:
Karen L. Snover, Cornell University
Phil A. Arneson, Cornell University

13. Symptoms
• The first symptoms appear as
small, light brown swellings of
the current or previous season's
growth.
• By the next season the swellings
turn olive-green in color with a
velvety texture.
• Over this growing season the
knots darken and appear to have a
hard, brittle texture.
• The hard, black knots are the
typical symptoms associated with
the disease.
©aps.net

14. Knots of varying size on
the twigs
Infected twigs often appear bent
at the tips because of extra
cellular growth on one side
©aps.net
©aps.net

15. Systematic position
• Kingdom : Fungi
• Phylum : Ascomycota
• Subdivision: Pezizomycotina
• Class : Dothideomycetes
• Order : Pleosporales
• Family : Venturiaceae
• Genus : Apiosporina
• Species : Apiosporina morbosa

16. Pathogen
• The fungus produces pseudothecia, fruiting structures that are
embedded in the black stroma on the surface of the gall.
• The mass of pseudothecia is often referred to as the
ascostroma.
Ascostroma
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17. Lifecycle
©ohioline.osu.edu

18. • Favourable condition
• Temperatures between 16°C and 27°C (60-80°F) are
ideal for the dissemination, germination, and
infection of new plant tissue.
• Mode of survival and spread
– Infected plant debris.
– By ascospores.

19. IDM
• A possible biological control agent for black
knot may be the fungal parasite, Trichothecium
roseum.

20. Bacterial Canker
• Distribution – world wide
Pathogen
• Pseudomonas syringae

21. Symptoms
• Cankers develop at the base of
infected buds on trunk and
scaffold limbs. Cankers spread
more rapidly above the point of
infection than below and only
slightly to the sides.
• This results in a long, narrow
canker. Cankers develop during
the fall and winter but are not
visible until late winter and early
spring.
©omafra.gov.on.ca

22. • Damaged areas are slightly sunken and
somewhat darker in color than
surrounding bark. As the trees break
dormancy in the spring, gum is formed
and flows down the outside of the tree.
• Cankers have a soured smell. The
bacterium is a weak pathogen and
causes serious damage only when a tree
is in a near dormant condition or
weakened due to unfavorable growing
conditions.
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23. Systematic position
• Kingdom : Bacteria
• Phylum : Proteobacteria
• Class : Gammaproteobacteria
• Order : Pseudomonadales
• Family : Pseudomonadaceae
• Genus : Pseudomonas
• Species : Pseudomonas syringae

24. • Pathogen
– Rod shaped, gram negative bacterium with polar flagella.
• IDM
– Avoid using high fertilizer rates in late summer.
– Succulent, late fall growth is more easily infected.
– Prune when trees are fully dormant (January and February).
– Trees showing signs of bacterial canker should be left and
pruned after all other trees have been completed.

25. Bacterial spot
Distribution
North America, Asia, Africa, South America, European union
History
First described in North America
Pathogen
• Xanthomonas campestris pv. pruni (Smith) Dye
Synonyms
• Xanthomonas arboricola pv. pruni (Smith) Vauterin et al.
• Xanthomonas pruni (Smith) Dowson

26. Symptoms
On Leaf:
• First small, pale green colour
irregular lesions are formed.
• Angular lesions surrounded by
yellow halo are formed.
• Inner portion of the lesion turn
black and drops out giving a
“shot hole” or “ragged”
appearance and the leaf falls off
prematurely. ©intermountainfruit.org

27. On Fruit:
• Large, sunken black
lesions are common on
some cultivars, while,
on others, only small pit
like lesions appear.
©omafra.gov.on.ca

28. On Twigs:
• Cankers are perennial and continue to develop in
twigs of 2 to 3 year old
• Inner bark is penetrated, resulting in deep seated
cankers which deforms and kills the twig.

29. Systematic position
• Kingdom : Bacteria
• Phylum : Proteobacteria
• Class : Gammaproteobacteria
• Order : Xanthomonadales
• Family : Xanthomonadaceae
• Genus : Xanthomonas
• Species : Xanthomonas campestris pv. pruni

30. • Pathogen
– Motile, aerobic, gram negative rod, 0.2 – 0.8 X 0.8-1.7µm with
single polar flagellum.
• Favourable condition
– Warm, moderate season with temperature of 19-28°c with light,
frequent rain accompanied by heavy winds & dews.
• Mode of survival and spread
– Has limited capacity for local dispersal by rainsplash.
– Pruning and insect damage by Cicada spp. transmit the disease.

31. IDM
• Planting resistant cultivars.
• No direct control methods are suggested, but
bactericides have been evaluated.
• Bud wood should be obtained from disease free trees,
preferably grown in arid region.

32. Plum Pox
Distribution – worldwide
History
• Plum pox symptoms were first observed in plums by plum growers in Bulgaria between 1915
and 1918 although some reports indicate symptoms were seen in Macedonia as early as 1910.
• However the first paper describing the viral nature of the disease did not appear until 1932
when Atanosoff named it "Sarka po slivite" meaning "Pox of Plum“.
Classification
• Group : Group IV(+ssRNA)
• Family : Potyviridae
• Genus : Potyvirus
• Species: Plum pox virus
Mode of transmission – Aphids (20 species)

33. Symptoms
• Plum pox virus symptoms
appear on leaves, fruits,
flowers, and seeds.
• Leaves and fruit show
chlorotic (yellowing) and
necrotic (browning) ring
patterns, and chlorotic bands
or blotches.
©gwoodcloud.org
©gardeningknowhow.com

34. • The fruit of plum can be misshapen and deformed.
• In eastern and central Europe, sensitive plum varieties
can exhibit premature fruit drop and bark splitting.
©ucanr.edu

35. IDM
• Use of resistant varieties.
• No direct control methods are suggested.
• Spraying insecticide could control the insect
vector.