Symptoms of plant diseases

Symptoms are the external and internal reactions or alterations of a plant as a result of a disease.

Anthracnose

Anthracnose of chilli
Anthracnose of mango Anthracnose of chilli

Anthracnose is recognized by necrotic and sunken ulcer-like lesions on the stems, leaves and fruits.
Anthracnoses are caused by fungal pathogens.

Examples


Blight

Blight disease
Leaf of taro showing Blight

Blight is characterized by extremely rapid browning and death of leaves, branches, twigs and floral organs. Blight affected foliage collapse. In warm climate blight affected plants appear as if these are burned.

Examples

Blotches

plant disease
Red rot affected stem of sugarcane showing blotches

A disease characterized by large, irregularly shaped, unpleasant spots or blots on leaves, shoots and stems.

Examples

  • Red rot of sugarcane caused by Colletotrichum falcatum .

Canker

plant diseases
Citrus fruits showing canker

Cankers are localized, necrotic lesions on stems leaves and fruits.

Examples


Chlorosis

Yellowing of normally green tissue (particularly, leaves) due to chlorophyll destruction or failure of chlorophyll formation. Chlorosis is common symptom in viral diseases of plants.

Curl

Distortion, thickening, shirking and curling (upward and downward) of leaves and or petioles.
Curl is the common symptom of viral diseases.
Leaf curl of papaya
A growing shoot showing symptoms of leaf curl


Examples


Damping off

Rapid death and collapse of very young seedlings. Fungus degrades the cell wall and middle lamella (cementing material between plant cell). Due to which affected root and stem lose the mechanical strength and plants collapse from just above the ground and die.

Downy mildew

Downy mildew of cucurbit
Downy mildew of cucurbit

Downy mildews appear as chlorotic and necrotic angular lesions on the leaves. This gives burned appearance of leaves and sometimes referred as 'wildfire'. The disease is devastating in the cucurbits.

Examples


Galls/Wart

Stem gall of coriander
Stem gall of coriander

Galls are the abnormal growth in roots, stem, leaves, inflorescence and fruits. Galls are produced as a result of hyperplasia and hypertrophy, which are induced by fluids secreted by insects and their eggs. Insect induces the gall for their own benefit to protect the eggs.

Examples


Hypertophy and Hyperplasia

Irregular enlargement in size of cells of any plant organs (stems, leaves, blossoms, roots) is called as hypertrophy. Irregular and abnormally increased cell division in any plant organs (stems, leaves, blossoms, roots) is called as hyperplasia. Hypertrophy and or hyperplasia eventually induce the gall/wart formation. In floral parts these activities result in phyllody.

Examples

  • Phyllody is induced due to 'hypertrophy' and 'hyperplasia' in white rust of crucifers caused by Albugo candida

Little leaf

Reduction in the size of leaf lamina is called as 'little leaf'. These are induced by phytoplasma.

plant pathology
little of brinjal

Examples


Malformation

Mango malformation Mango malformation
Malformation in shoot of mango Malformation in inflorescence of mango

Enlarged portions of plant organ (stems, leaves, blossoms, roots) is called as malformation. Malformation in young apex ceases the apical growth and plants become stunted.

Examples


Necrosis

When a cell or tissue die and degenerate, it is termed as necrosis. The necrotic portion of the plant darken and wilt.

Phyllody

Green ear disease of bajra
Head of bajra showing phyllody

Phyllody is the abnormal development of floral parts into leafy structure. Excessive production of leaves in place of shoots and blossoms is known as phyllody. Phyllody is induced by hypertrophy and hyperplasia. Phyllody is more common in the diseases caused by mycoplasma and viruses. Some of the fungal diseases also induce phyllody in plants.

Examples


Powdery mildew

Powdery mildew
Powdery mildew on akarkarha leaves

Powdery mildews are the superficial growth of fungal mycelia and their reproductive structures on leaves of infected plants. Powdery mildew appear as powdery, cottony mass on one or both the surface of leaves.

Examples


Scab

Localized lesions on host fruit, leaves tubers, etc are called as scab. Scabs are usually raised or sunken and cracked.

Diseases of apple
Scabs on fruits of apple

Examples

  • Scab of potato caused by Streptomyces scabies.
  • Scab of apple caused by Venturia inaequalis.

Spot

leaf spot disease of groundnut
Tikka disease showing spots on leaves

Localized lesions on host leaves and fruits consisting of dead and collapsed cells are called as spots. Spots are most common in the fungal diseases. Spots are often black colored with various shapes and sizes.

Examples


Rust

Stem rust of wheat
Stem rust of wheat

Rusts are the powdery pustules on the leaves, stems and fruit. The color of rust is highly variable among the various diseases. These appear as red, brown, black, yellow, orange. Rust is the powdery mass of fungal spores. Most of the rust diseases are caused by fungi of order Pucciniales. Among which, genus Puccinia is more common.

Examples


Smut

Smut
Infected inflorescense of doobgrass showing typical symptoms of smut disease

Smuts are characterized by black soot or dirt like powder consists of fungal chlamydospores. Smuts are caused by fungi belonging to order Ustilaginales. Smut appears on the grains, which are transformed in to black mass of powder.

Examples

  • Loose smut of wheat caused by Ustilago tritici.
  • Covered smut of wheat caused by Ustilago hordei.
  • False smut of rice caused by Ustilaginoidea virens.
  • Loose smut of barely caused by Ustilago nuda.
  • Smut of doob-grass caused by Ustilago cynodontis.

Wilt

wilt disease
Wilt of chilli caused by Fusarium oxyporum f. sp. capsici. 

Wilt disease is marked by generalized loss of turgidity and drooping of leaves or shoots and rapid death of whole plants. Wilt affects the vascular bundles of the plants and chokes the xylem vessels. Wilt are caused by Fusarium spp.

Examples


Warts

Wart are rounded excrescences or protuberances on tubers and stems of plants.

Examples

  • Wart disease of potato is caused by Synchytrium endobioticum.

Witches' broom

Witch's broom
Witch's broom

Witches' broom is a deformity in the branching and shape of leaves in plants where a dense mass of shoots with small leaves grow from a node resembling a broom. witches' brooms in plants are caused by phytoplasmas.

Examples


Vein clearing and vein banding

Vein clearing and vein banding
Ageratum leaves infected with yellow vein mosaic virus showing vein clearing and vein banding

Vein clearing is the entire disappearance of chlorophyll throughout the networks of veins.

Examples


Vein banding is marked by the white and green areas in between the veins of the leaves.

Examples


Content first created on 20-05-2020
last updated on 17-12-2023