This document summarizes common plant disease symptoms. It describes two types of symptoms: signs which denote the pathogen itself, and hypo-/hyperplasia symptoms relating to under- or overgrowth. Specific hypo-/hyperplasia symptoms discussed include dwarfing, mosaic patterns, blisters, galls, and leaf curls. Necrosis symptoms result in tissue death, such as anthracnose lesions, cankers, and blights affecting leaves and stems. The document also briefly mentions three types of mildew fungi that appear white, gray, or powdery on plant surfaces.
2. Symptoms Signs
Denotes the presence of
either the pathogen itself or
any of its structures and is
more reliable in accurate
diagnosis.
It is the expression of the
external and internal
reactions or alterations of a
plant as a result of a disease.
3. 1) HYPOPLASIA
• Albinism: Complete absence of
chlorophyll pigment
Reduction in growth, resulting in stunting or dwarfing
4. • Dwarfing: The subnormal development resulting in reduced plant
height and other plant parts
Barley yellow dwarf
5. • Little leaf: Severe reduction in leaf size and stunting of
internodes
Little leaf of brinjal
6. • Mosaic: Uneven development of chlorophyll resulting in light green
patches intermixed with green areas
Bean yellow mosaic
7. 2) HYPERPLASIA ND HYPERTROPHY
• Hyperplasia: Plant over growth due to increased cell division.
• Hypertrophy: Plant over growth due to abnormal cell enlargement.
Blisters: Localised protrusions
Blister blight of tea
8. • Bunchy top: Numerous, upright, leathery leaves in clusters at the tip
Banana bunchy top
9. • Galls : Localized enlargement of plant parts
Crown gall in rose by Agrobacterium tumefaciens
10. • Green ear : Proliferation of floral organs into greenish leaf-like
structures
Green ear of Bajra
11. • Leaf curls : Thickening, curling and distortion of leaves
Leaf curl of chilli
12. 3) NECROSIS
• Disorganization and destruction that results in death of tissues.
• Anthracnose : Ulcer-like necrotic and sunken lesions
13. • Blast : Spindle shaped areas with grayish center surrounded by
brownish margin which after coalescence gives a burnt appearance
14. • Cankers : Deep seated localized corky necrotic areas.
15. • Blight: General and extremely rapid browning and death of leaves,
branches, twigs, and floral organs.
Late blight of Potato caused by Phytophthora infestans
Early blight of Tomato caused by Alternaria solani
16. • Damping-off : Water soaked sunken areas at the collar region leads to
sudden collapse of seedlings.
17. 17
• Die – Back : Characteristic death of plant parts from tip to down wards
Citrus die back Mango die back
19. Mildews consist of white, grey, brownish or purplish pathogen growth on
the host surface.
Downy mildew is characterized by a tangled cottony or downy growth
mostly on the lower surface of the leaves or other plant parts.
20. • Powdery mildew consists enormous number of spores are formed on
superficial growth of the fungus giving a dusty or powdery appearance on
the host surface. Black minute fruiting bodies may also develop in the
powdery mass.
