Plant diseases caused by Bacteria 1. Spots and Blights Wild fireSpotSpeck 4. Vascular wilts wiltFire...
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Transcript of Plant diseases caused by Bacteria 1. Spots and Blights Wild fireSpotSpeck 4. Vascular wilts wiltFire...
Plant diseases caused byBacteria
1 .Spots and Blights
4 .Vascular wilts2 .Soft rots
3 .Galls 6 .Canker and Gummosis5 .Scabs
Wild fire Spot Speck
wilt Fire blightBlack rot
Canker and GummosisCanker
1.Bacterial spots and blights
a- Wildfire of tobaccoDisease name: Wildfire Plant: Tobacco (Nicotiana tabacum L.)Pathogen: Pseudomonas syringae
Symptoms:
Round spots: brown in centers and whitish yellow halos
Adjacent spots coalesce → large dead area on the leaf
b- Bacterial spot of tomato and pepper
Disease name: Bacterial spotPlant: Tomato, PepperPathogen: Xanthomonas campestris
Symptoms:
Tomato
On unripe fruits: small water soaked, slightly raised spots.
spots sometimes have greenish-white halos → dark brown with scabby surface.
Pepper
On unripe fruits: small water soaked, slightly raised spots.
spots sometimes have greenish-white halos → dark brown with scabby surface.
c- Bacterial speck of tomato
Disease name: Bacterial SpeckPlant: TomatoPathogen: Pseudomonas syringae
2.Bacterial vascular wilts
a- Bacterial wilt of cucurbitsDisease name: Bacterial wilt Plant: Cucurbitaceae Pathogen: Erwinia tracheiphila
Symptoms:
Drooping and wilting of infected leaves, which shrivel and dry up.
Infected stems become soft and pale then shrivel (ذبول), hard and dry.
b- Fire blight of Pear and Apple
Disease name: Fire blightPlant: Pear, ApplePathogen: Erwinia amylovora
Symptoms:Apple
Bark turns brownish black and soft → shrinks and hardens
Brown, black blotches along midrib and between veins then curl and shrivel.
Bacterial exudates (ooze) from apple fruit and stem.
Pear
Brown, blak blotches along midrib and between veins then curl and shrivel.
Immature fruit become water soaked, then shrivel, turn
black.
V-shaped chlorotic blotches at the margins of the leaves → chlorosis progress toward the midrib → affected area turn brown and dry.
Cabbage and cauliflower heads are discolored.
Symptoms:
3.Bacterial soft rots
Bacterial soft rots of vegetablesDisease name: Bacterial soft rots Plant: Vegetables ( potato, carrot,..), annual
ornamentals (iris), succulent stems, stalk or leaves (cabbage, lettuce,..).
Pathogen: Erwinia carotovora
Symptoms:
Affected area becomes soft and mushy, the surface becomes discolored and depressed.
Cracks develops the slimy mass exudates to the surface and turn brown.
Cruciferous plants and onions give off repulsive odor.
4.Bacterial galls
Disease name: Crown gallPlant: Woody and herbaceous plants (> 60
families), mostly on pome and stone fruit trees, brambles and grapes.
Pathogen: Agrobacterium tumefaciens
Symptoms:Small, round, whitish soft
overgrowth on the stem
and roots (mainly near the
soil line) → the tumor
enlarge and become brown
(death and decay of
peripheral cells). Some
tumors are spongy while
others become woody and
hard.
5.Bacterial canker and gummosis
a- Bacterial canker and gummosis of stone fruit trees
Disease name: Bacterial canker and gummosis
Plant: Stone fruit trees (apricot, pear,olive,…)
Pathogen: Pseudomonas syringae
Bacterial canker:
Formation of cankers girdled the trunk or branches. Within few week, the branch or entire tree above the canker die.
Leaves show curling and turn yellow.
Symptoms:
Symptoms:
Similar lesions are on young leaves, twigs and fruits.
Small round light green spots (lesions) → they rupture and appear corky with brown sunken centers and yellow halo.
Premature fruits drop.
6.Bacterial scabs
Common scab of potatoDisease name: Common scab Plant: Potato, root crops (beets,
radish,..)Pathogen: Streptomyces scabies
Symptoms:
Small brownish raised spots → enlarge, coalesce and become corky.
The lesions extend 3-4 mm deep in tuber
1.DodderCuscuta spp.
Plant: alfalfa, onion, sugar beets, some ornamentals and potato.
Parasite: Cuscuta spp.(dodder)
Symptoms:
Orange or yellow strands around the
stem and the other aboveground parts
of the plant. The parasite enter their
haustoria directly to the phloem of the
host.
During late spring and in summer,
dodder produces clusters of white,
pink or yellowish flowers.
Infected host produce poor yield and
may be killed by parasite.
2.WitchweedStriga spp.
Plant: economic plants (corn, sugarcane, rice, cowpeas, tobacco, small grains,..)
Parasite: Striga spp.