Plant Pathogenic bacteria

3. BACTERIA: Single celled microorganism
whose genetic material is not bound by a
membrane. So it has no well defined nucleus.

4.  About 1,600 bacterial species are
known .Most are strictly
saprophytic and such as are
beneficial to humans because help
in decompostion ,Severall species
cause diseases in humans and
animals.

5.  About 10,000 species cause diseases in
plants , Most plant pathogenic bacteria are
rod shaped the only exception being
Streptomyces, which is filamentous, cell
walls of bacteria of most species are
enveloped by a viscous, gummy material
which, if thin and diffuse, is called a slime
layer but if thick, forming a definitive mass
around the cell is called a capsule.

8. Causal organism:
Agrobacterium tumefaciens
Host: Severall plant species are susceptible
especially rose, grape, pome,stone fruits, shade
and nut trees, many shrubs and vines, and
perennial garden plants
Symptoms :
Galls forms on the roots or crowns of trees, and
rarely on aerial parts of the tree. Galls vary in
size from several mm to 15 cm in diameter,
tumor-like swellings that become brown, woody
knots with age and may be soft or hard. Small
galls may be confused with callus tissue at
wound sites, such as graft unions.

11.  Bacterial Ring Rot of Potato
 C.O:Clavibacter michiganensis
 Symptoms: The disease is called "bacterial ring
rot" because the rot appears in the vascular ring
of the potato tuber. In severely affected tubers,
the vascular ring is brown to black in colour,
often with a cheesy or creamy ooze and many
hollow spaces. Dry cracks can usually be found
on the surface of the tubers. In milder cases, the
vascular ring may show only broken, black lines
or a yellowish discolouration. Leaves of infected
plants may show interveinal yellowing, wilting,
or no symptoms.

13.  vascular Diseases :fire blight on apples, pears, and
other rosaceae crops; the bacterial wilt of cucurbits,soft
rots
FIRE BLIGHT OF PEAR AND APPLE
causal agent: Erwinia amylovora.
Symptoms:Infected flowers become water soaked, then
shrivel,turn brownish black, and fall or remain hanging in
the tree .black blotches along the midrib and main veins or
along the margins appeared as the blackening progresses,
the leaves curl and shrivel, hang downward. Infected
small, immature fruit become water soaked then turn
brown, shrivel, turn black, and may cling to the tree for
several months after infection. Under humid conditions,
droplets of a milky colored,sticky ooze may appear on the
surface of any recently infected part. The ooze usually
turns brown soon after exposure to the air.

15.  Disease causing: soft rots of numerous fleshy
fruits, vegetables, ornamentals and blackleg
of potato
BACTERIAL SOFT ROTS OF VEGETABLES
cauasal agent : Erwinia carotovora pv.
carotovora, E.chrysanthemi,
 Symptoms: Soft-rot symptoms begin as a small
water-soaked lesion, which enlarges rapidly in
diameter and in depth.The affected area
becomes soft while its surface becomes
discolored. Tissues within the affected region
become cream colored and slimy, disintegrating
into a mass of disorganized plant cells.

17. C.O: Erwinia carotovora/
Pectobacterium carotovorum

18.  Upper part:
Stunted, yellowish
 Lower part:
Stem dark brown
 Young plants:
Fail to develop further
and typically die

19.  Pungent smell
 Loose mass
Pectobacterium
carotovorum

20.  Disease causing: bacterial stripe of sorghum
and corn leaf blight of all cereals red stripe
and top rot of sugarcane ,wildfire of
tobacco, halo blight of oats and other cereals
WILDFIRE OF TOBACCO
causal agent: Pseudomonas syringae pv. Tabaci
Symptoms: Wildfire causes losses in both the
seedbed and field. Affected seedlings may be
killed. In tobacco plants already in the field,
wildfire causes large irregular, dead areas on the
leaves.

22.  Causal agent: Pseudomonas syringae pv. lachrymans.
Symptoms: It affects the leaves, stems, and
fruits of cucumber. At first, small circular spots
appear on the leaves and soon become large,
angular to irregular, water-soaked areas. In wet
weather, droplets of bacterial ooze exude from
the spots on the lower leaf surfaces. In dry
weather the exudate becomes a whitish crust.
Affected tissues die, turn white, and cracks
appeared.

24.  Disease causing: common blight of beans ,angular
leaf spot of cotton bacterial leaf blight of rice
bacterial blight or stripe of cereal ,bacterial spots of
stone fruits ,tomatoes and peppers
 ANGULAR LEAF SPOT OR BACTERIAL BLIGHT OF COTTON
 causal agent : Xanthomonas campestris pv.
malvacearum.
 Symptoms: Small, round, water-soaked spots appear
on the undersides of cotyledons and young leaves and
on stems of seedlings soon after emergence. In later
stages,the spots on leaves appear as angular, brown
to black lesions of varying sizes which has given the
name “black arm” to the disease, symptoms also
produce on stems and young cotton bolls.

25.  Angular brown spots on
leaves (Angular leaf spot)
 Spread along veins, hence
black vein
 Watery spots on cotyledons

26.  Death & shedding of leaves
 Stems blackened, easily broken (black
arm)
 Young bolls fall

27.  CITRUS CANKER
Causal agent : Xanthomonas axonopodis pv. Citri
symptoms: Lesions are produced on young
leaves,twigs, and fruits. The lesions at first
appear as small, slightly raised, round, light
green spots. Later,they become grayish white,
and appear corky with brown, sunken centers.
The margins of the lesions are often surrounded
by a yellow colour.

28.  Watery spots on leaves
 Later on spots become
thickened, brown and
corky.

29.  In severe attack
symptoms produced on
petioles, midrib and on
fruits
 Causes premature
defoliation

30. Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gamma Proteobacteria
Order: Xanthomonadales
Family: Xanthomonadaceae
Genus: Xanthomonas
C.O Xanthomonas
oryzae pv. oryzae

31.  Temperature (25-30°C)
 High humidity
 soil pH 4 - 8.8
 Optimum pH being 6-6.50
 Rain fall
 Deep water

32.  This disease appeared
1884 in Japan
1970 in Africa
1977 in Pakistan
 Most important in all rice growing areas
 50% yield reduction in world’s
Production

33.  Yellowish stripes on
leaves
 Lesions on leaves
turn yellow to white
 Later become
grayish

34.  Infected leaves dry quickly
 Bacterial ooze on young lesions
 Panicles sterile and unfilled but not
stunted
Infected field

35.  Disease causing: Bacterial scabs include
common scab of potato.
Common scab of potato
causal agent : Streptomyces scabies
Symptoms: Common scab of potato affects
mostly the tubers. Infected tubers at first
develop small, brownish. Later, the spots usually
enlarge and become corky.

37.  ROOT NODULES OF LEGUMES
causal agents: Rhizobium, Bradyrhizobium,
Azorhizobium, and Frankia.
Symptoms: Root nodules are well-organized
structures produced on the roots of most legume
plants. Within the root hair cell, bacteria
become embedded.