Ex. No. 14.                                                            Study of Bacterial diseases

Bacteria: Bacteria are prokaryotic, microscopic, unicellular, rigid cell wall organisms which are achlorophyllous. They are reproduced by binary fission (asexually).

Gram negative bacterium: Xanthomonas, Pseudomonas, Erwinia, Agrobacterium

Gram positive bacterium: Streptomyces, Clavibacter

Disease name	Causal Organism				Symptoms
Bacterial Leaf Blight of rice	Xanthomonas oryzae pv. oryzae				Straw colour necrotic patches with yellow wavy margin are appear
Bacterial leaf streak		Xanthomonas oryzae pv. oryzicola
Black arm of cotton/ Angular leaf spot	Xanthomonas axonopodis  pv. malvacearum (Both internally and externally seed borne)				Black lesions are formed on the leaves and breaking the stem, hang typically a dry black twig to give a characteristic ‘black arm’ symptom
Citrus canker	Xanthomonas citri				Corky outgrowth on the surface of leaves, twigs and fruits with surrounded by yellow halo (except fruits)
Soft rot of carrot	Pectobacterium carotovorum				Softening and disintegration of tissues
Potato Scab	Streptomyces scabies				Bulged lesions  (Soil borne bacterium)
Black rot of cabbage	Xanthomonas campestris pv. campestris (1st seed borne bacterium)				‘V’ Shaped chlorotic regions
Tundu disease of wheat	Corynebacterium tritici				The disease is an example of nematode bacterial complex disease.
Fire blight of apple and pear			Erwinia amylovora( 1878, T.J.Buriill) 1st Bacterial disease in World
Bacterial wilt of cucurbits			Erwinia tracheiphila (E.F.Smith)
Crown gall of apple and pear			Agrobacterium tumefaciens New name is Rhizobium radiobacter (This bacterium is an example plant pathogenic bacterium used for transfer of genetic material from one plant to another plant, Scientist’s best friend)
Moko wilt of Banana			Ralstonia solanacearum (Strain no: 2)
Brown rot of potato			Ralstonia solanacearum (Strain no: 3)
Bacterial wilt of Solanaceous vegetables				Ralstonia solanacearum (Strain no: 1)

Bacterial leaf blight of rice Other name: Bacterial Blight, White withering disease 

Causal organism: Xanthomonas oryzae pv. oryzae Ishiyama

Symptoms: Kresek stage (Nursery stage): At the seedling transplanting stage, the infected plants are wilting

1.       On mature plants, small water soaked lesions are appear

2.       Wavy margin are appear on inner portion of the leaves

3.       Complete death of entire plant is called hama lodoh

4.       Pale yellow discolouration and bacterial ooze out occur

5.       It’s a gram negative bacterium with rod shaped, Single polar flagellum

6.       Mode of spread : Anemochory and Hydrochory

7.       Spray Agrimycin- 50 for manage this disease

Black arm of cotton Other name: Angular leaf spot, Boll rot, Black vein

Causal organism: Xanthomonas axonopodis pv.  malvacearum E.F. Smith

Symptoms: Small dark green water soaked areas develop on the lower surface and turn into reddish brown colour

1.       Blackening of veins and veinlets (necrosis)

2.       On stem there appear elongate grayish to black lesions

3.       Gummosis and Bacterial ooze out also appear

4.       On the bolls, small water soaked lesions are appear and turn brown later

5.       It’s a gram negative bacterium with rod shaped, Single polar flagellum

6.       Rain fallowed by bright sunshine favours the disease

7.       Spray streptomycin for manage this disease