Types of Bacteria Infecting Plants

By producing large amounts of polysaccharides that block the xylem vessels.

Proteobacteria

Helicobacter pylori

By insects such as aphids that suck plant sap.

Nitrogen compounds

Xanthan gum

Seed treatment, treatment of vegetative propagation material, foliar sprays, therapy, immunisation, disease forecasting

0.02% streptocycline treatment of seed tubers of potato against brown rot disease

Selection, breeding, and other methods are used to evolve resistant varieties

Pencillin and vancomycin are used for disintegration of the crow gall

It helps in timely and economic management based on observations and prediction models

Screening for resistance sources under artificial conditions and evolving resistant varieties

A sign of plant disease is physical evidence of the pathogen, such as a bacterial exudate or fungal growth. A symptom of plant disease is a visible effect of the disease on the plant, such as a change in color, shape, or function.

Symptoms of bacterial canker on tomato, capsicum, and chilli plants include seedlings dying, older plants wilting and dying, leaves turning yellow and wilting on one side, and the development of cankers on the stems and fruit. The tissue inside the stems also becomes discolored.

The symptoms of bacterial soft rot include a wet, slimy, and soft rot that affects any part of the vegetable crop, including heads, curds, edible roots, stems, and leaves. The affected areas may also have a disagreeable odor.

On lettuce, the symptoms include large brown to black circular areas that start as small translucent spots, usually on the outer leaves. On tomatoes and capsicums, the symptoms are greasy spots on leaves and stems that go from tan to black, and the fruit may have circular spots with a central scab. On cucurbits, the symptoms begin as small water-soaked/greasy spots on the underside of leaves with corresponding yellowing on the upper side, and the fruit may produce a light-brown ooze from water-soaked markings.

The symptoms of bacterial wilt include wilting, yellowing, and stunting of the plants, but they may also wilt rapidly and die without any spotting or yellowing. The vascular tissue appears brown and water-soaked, and a white ooze appears when pressure is applied to affected tubers or stems.

On beet, the symptoms are irregular, round leaf spots with a grey center surrounded by a purple margin. On spring onions/shallots, the symptoms are pale yellow to light-brown lesions with a water-soaked appearance around the margins, and the outer leaves wither and die while the youngest leaf turns lemon to light-green. On leeks, the symptoms are brown streaking on the shank.

Exclusion, eradication, plant sanitation

Citrus canker in Florida, USA during 1914-1927

Reduces the intensity of the disease

Sterilization of the cutting knife by flame or by 0.1% KMNO4 solution

Delinting of cotton seed with concentrated sulphuric acid

Removing dead plant parts and protecting cut surfaces with bactericides

Aphids use needle-like mouth parts to puncture plant stems and tap directly into the phloem vessels, which transport sugars.

The Mycoplasma bacteria grow inside aphids and are introduced into plants when the aphids feed, acting as an efficient means of transmission.

Common symptoms include leaf discoloration, absence or abnormal coloration of flowers, and general weakening of the plant.

Bacteria can survive in plant debris, seeds, soil, water, on inanimate objects, inside insects, and in association with perennial host plants.

Some bacterial diseases require specific temperature conditions to progress, e.g. Pseudomonas syringae below 22°C and Xanthomonas campestris above 22°C on dry bean plants.

Bacteria can enter through natural plant openings like stomata, wounds or abrasions, by being sucked in, or by being introduced by insect vectors during feeding.

Vibrio cholerae

Xanthan gum

It causes black rot by blocking xylem vessels

By insects that suck plant sap, such as aphids

Proteobacteria

Stunted growth and leaf curling

To protect against leaf spots and blights

Developing resistance sources for pathogens

Using bacteriophage population as an index

Breeding for desirable traits

Protecting against bacterial diseases

Streptomycin sulphate

Practicing crop rotation with cereals

Delinting cotton seed with concentrated sulphuric acid

Exclusion of disease entry from diseased to healthy tracts

Protecting injured plant parts during cultural operations

Soaking rice seeds in 0.025% streptocyclic solution

Immediately growing tobacco after maize

To transport sugars from the leaves to other parts of the plant

Aphids use needle-like mouth parts to puncture the plant stems and tap directly into the sugar-rich phloem.

By wind-blown soil and sand particles that cause plant wounding

All of the above

Both (b) and (c)

Mycoplasma bacteria grow inside aphids and other sap-sucking insects and are then introduced into plants.

A sign is physical evidence of the pathogen, while a symptom is a visible effect on the plant caused by the pathogen.

Seedlings may die, and older plants may wilt and die eventually.

Pseudomonas spp., Erwinia spp.

Begin as small water-soaked/greasy spots on underside of leaves with corresponding yellowing on upper side; fruit may produce light-brown ooze from water-soaked markings.

Wilting and rapid death of plants without any spotting or yellowing.

Small dark spots on leaves.