agri 41. Plant path lect

Plant Pathology

Scientific study of plant diseases, what causes them, how and why they occur, and how to manage them.

Study of plant pathogens and diseases they cause in plants

Understanding the components of plant disease, and the mechanisms by which plant pathogens induce disease in plants

Development of methods in preventing, controlling and management of plant diseases to reduce the damage on plants

Mycology, Bacteriology, Nematology, virology

Plant Pathology Composed of

Mycology

the study of fungi & fungal-like oomycetes

Bacteriology

study of typical bacteria, fastidious bacteria, mollicutes (e.g. Phytoplasma and Spiroplasma)

Nematology

the scientific discipline concerned with the study of nematodes, or roundworms

Virology

the study of virus and viroids

1674

when microscope was invented ?

Heinrich Anton de Bary

he showed that potato late blight was caused by a fungus Phytophthora infestans.

Father of Mycology who started the scientific study of plant diseases; proved that the spores caused the disease.

P. infestans

Potato late blight caused by

Hemileia vastatrix,

In the 1870s, a new disease, coffee rust, caused by the fungal pathogen?

Bipolaris maydis

Southern Corn Blight

• Disease outbreak in 1970

• Caused by a T race of the fungus,

1910

first course in Plant Pathology taught as Botany 4 under the Agronomy dept.

Charles Baker

in 1914 He Published “the Lower Fungi of the Philippines Island” - a review of Philippine plant diseases. in

1917

when the Department of Plant pathology was Born and course offered as Plant Pathology

Plant Quarantine Act.,1922

what is enactment of Republic Act 3027??, and it establish when ??

Gerardo Ocfemia

in 1933 he is the first Filipino department head; “Dean of Filipino Plant Pathology”

1950-1960

• Studies on etiology and control of leaf and seedling diseases

• Development program in upgrading staff and physical facilities

1963

Philippine Phytopathological Society was developed

Exconde and co-workers

when 1978, who controlled corn downy mildew by seed treatment

Davide

in 1983 He developed Biological control against nematodes

• Reduction in yield

• Reduction in quality of produce

• Deterioration of produce during storage, marketing and transport

Direct Losses due to Plant Diseases

• Pre-dispose plants to the attack of other plant pathogens/pests

• Increased agricultural inputs

• Limits the kinds of crops to be grown in an area

• Plant pathogens produce toxins detrimental to humans and animals

• aflatoxin by Aspergillus flavus

Indirect losses

• Abnormal physiological process

• Caused by a pathogen

• Resulting to abnormal morphology (symptoms)

• Eventually seen as reduction in economic value or yield loss

Salient Features of Plant Disease

• TRANSLOCATION

• PHOTOSYNTHESIS

• TRANSPIRATION

• RESPIRATION

• PERMEABILITY

• TRANSCRIPTION AND TRANSLATION

• ABSORPTION

Physiological Processes Affected

• Disturb the metabolism of plants through enzymes, toxins, growth regulators

• Directly absorb nutrients

• Grow in plant organs, preventing their function (sooty mold, phytoplasma)

How Do Pathogens Affect The Physiology Of Plants?

• “Any physiological disturbance that prevents the normal development of the plant and reduces its economic value”

• Disturbance is caused by a pathogen that result to. changes in form, function and integrity of the plant, and may lead to partial impairment or death of plant part or the entire plant

• Diseased plants yield less than a healthy one

causes of plant disease

Disease

disturbance caused by a pathogen; communicable; interaction between the host, the pathogen and the environment.

Disorder

disturbance caused by soil and environmental factors; non- communicable; no interaction between host and pathogen

Physiological Disorder Environmental Factors

In Physiological Disorder:

• occur in the absence of pathogens

• cannot be transmitted from diseased to healthy plants

• caused by the lack or excess of something that supports normal functioning of the plant

Temperature, Lack of Oxygen, Air Pollutants, Ozone, Nutrient Deficiency, Toxicity

What are the Environmental factors

Fungi, Bacteria, Nematodes, Virus, Viroids, Phytoplasma, Flagellate Protozoa, Parasitic Flowering Plants

Plant Pathogen: Causal Agent of Plant Disease compose of

Heterophs, Biotrophs, Saprotrophs, Nerotrophs

True Fungi compose of

Heterophs

obtain their carbon and energy from other organisms

True Fungi

• Possess true nuclei and typical cellular organelles

• Cell wall composed of chitin and glucan

• Possess vegetative structure composed of branched, filamentous threads called hypha (plural: hyphae)

• Masses of hypha are called mycelium (plural: mycelia)

• Mycelium may have cross walls or septa (septated) or no cross wall (coenocytic)