Plant Pathology Introduction-Plant Care From Biotic & Abiotic

PLANT PATHOLOGY INTRODUCTION:
Plant pathology is a science which covers all the aspects related to diseased plants such as causal organisms, their life cycle, diagnosis, physiology, population dynamics and management. Any abnormal functioning in the physiology of plants is designated as “disease”. This may be caused by biotic factors or “disorder” due to Abiotic factors. Generally these two words can be used alternatively. Biotic and Abiotic factors have been classified as follows:

BIOTIC

• Prokaryotes
• Fungi
• Nematode
• Virus Viriods Mycoplasma

ABIOTIC

• Temperature Light
• Nutritional deficiency
• pH extreme
• Mineral imbalance Wind
• Pollutants

DISEASE OR DISORDER:

All the biotic factors include microscopic and submicroscopic organisms. Followings are some terms related to study of microorganisms:
PARASITES (BIOTROPHS):
These are the microorganisms which take their nutrition from living organisms.
PATHOGENS:
These are the parasites which cause diseases in humans, animals and plants. Higher Plants

OBLIGATE PARASITES:

These are parasites which strictly live only on living organism for their nutrition and multiplication.

SAPROPHYTES:
These are microorganisms which get their nutrition from dead organic matter. These are also known as saprotrophs.
OBLIGATE SAPROPHYTES:
These are microorganisms which live only on dead organic matter to obtain their nutrition.
FACULTATIVE SAPROPHYTES:
The organisms which are originally parasites but can live saprophytically i.e. on dead organic matter in the absence of living host.
FACULTATIVE PARASITE:
The organisms which are originally saprophyte but can get nutrition from living host in the absence of dead organic matter.
SYMBIOSIS:
Mutual beneficial relation of host and parasite.
ANTAGONISM:
Counter action of two microorganisms against each other e.g. fungus Trichoderma harzianum is antagonist to many fungi. 
SYNERGISM:
It is the combined effect of two microorganisms on host plant.
PATHOGENESIS:
All the disease events in host plant starting from infection to development of symptoms.
INFESTATION:
It is just the presence of microorganism on the surface of the host.
INFECTION:
When pathogens get entry, start getting nutrition and disturb the normal
physiology of the plant.
SYMPTOM:
Physiological expression of the host as result of infection is called symptom.

BRIEF DESCRIPTION OF PLANT PATHOGENS:

PATHOGEN	MORPHOLOGY	SIZE	SYMPTOMS
Fungi	Microscopic to Macroscopic, Branched, Filamentous, Somatic structure	Few micrometers to several meters in length. 0.5 μm-10 μm in diameters	Leaf spots, Gummosis, Powdery Mildew, Downy mildew, Rust, Smut, Blight, root rot of different crops.
Bacteria	Microscopic, Rod shaped (Bacillus), Spherical (Coccus), Comma shaped (Vibrio), Spiral (Spirillum)	0.6-3.5 μm in length 0.5-1.0 μm in diameter	Leaf spots, Blight, Canker, soft rot, Scab and Gall formation in vegetable and fruit crops.
Virus	Sub-microscopic, rod shaped, Spherical or polyhederal, flexous	480-2000 nm in length 10-13 nm wide Polyhedral viruses 17-60 nm in diameter	Yellowing, Mosaic, Mottling, Ring spot, Necrotic lesion, Curling, Rolling and Enation of leaves. Dwarfing, Stunting of Plants
Nematode	Microscopic, eel shaped	300-1000 μm 4 mm in length 15-35 in width	Nutritional deficiency like symptoms, Gall Formation, Stunting, Rottening of roots, Bushy appearance of roots.

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Here You Can Find Plant Disease and Pathogens (Fungi, Bacteria, Molllicutes, Parasitic higher plants, Parasitic Green Algae, Nematodes, Protozoa, Viruses, Viroids,Prions) Diagnosis and Treatment, Control Against Plant Disease. Laboratory Experiments & Work. Plant Pathology Lab Manual. House Plant-Trees Care Guide, Snake Plant Care, Pothos Plant Care, Plant Care for dummies, Plant Care  Printable, Products, Plant Care Tips, Symbols, Tags, Database, Careers, Websites, Apps & Card.

Written By:

Dr.Qaiser Shakeel

Tahir Mahmood

Department of Plant Pathology-Agriculture

The Islamia University of Bahwalpur-Pakistan.