Plant diseases

Some micro organisms cause diseases in plants.

The study of disease condition is known as Pathology

The Organisms that cause disease are called Pathogens

Pathogens are present among bacteria, viruses, fungi and protozoa.

Spread of disease from one individual to another is called transmission.

In some cases pathogen may be transferred by agents called Vectors.

Study of diseases in plants is called Plant Pathology

The changes in the functioning of the bodies shown in disease conditions are called Symptoms.

We will study few diseases affecting plants like Rice, Wheat, Sugarcane and Ground nut.

Leaf Blight in Rice Is caused by a bacteria. The disease occurs during the months of July to October It is characterized by the presence of a long yellow or straw

coloured lines with wavy margins on leaf. The diseased leaf dries up from the tip to base. In severe infection, entire paddy crop gives a burnt appearance. Bacteria spread from affected leaves to healthy leaves through

droplets of water or by direct contact of healthy leaf with an affected leaf.

Even seeds are affected by this disease. Sowing of infected seeds lead to the reappearance of the

disease in the next crop. Infected seeds should be treated with chemicals or hot water

before sowing

Leaf Blight in Rice :

In severe infection, entire paddy crop gives a burnt appearance

Blast of Rice Is produced by a fungus. Symptoms are prominent on leaves. Infection also occurs on leaf sheaths and stem parts

including the grain. Steam and leaf are covered with fluffy white hyphae of

the fungus. Plant cells in the infected area are killed by the fungus

and the part with dead cells changes its colour to brown.

Central part of the spot appear pale yellow with a dark brown border. If the leaves are infected early, they drop off. Grain falls off if the infection occurs below the grain.

There will be a loss in total yield of the grain.

Blast of Rice :

Silk fabrics are -bright strong

and light in weight

Wheat Rust The most common fungal disease in wheat.

Brown or rust coloured pustules appear on leaves and stem.

Infection causes premature falling of leaves and reduces yield.

variety of wheat resistant to rust diseases have been developed.

Wheat Rust :

A common disease in sugar-cane is red rot. Leaves are affected by disease. The inner part of cane become red in colour. Diseased cane should not be allowed to grow in

the field. It should not be used for sowing in the next

season. Sugar-cane plants with this disease should be

taken out and burnt far away from the field. Disease resistant varieties should be used to

prevent the attack of this fungal disease.

Red rot in sugarcane:

Tikka Disease is a common disease in ground nut .

In the diseased condition, many circulars spots appear on the surface of the leaf .

The conidia of the fungus present in soil or those present in the fruit shell is the source of infection.

Use of fungicides controls the disease.

Tikka Disease :

Presentation by:

CVVMMK DhavejiSchool Assistant ScienceTaylor High School Narsapur- 534275Andhra Pradeshmuralidhaveji@yahoo.com