Plant Pathology Lecture Notes Flashcards

Comprehensive vocabulary flashcards covering the definitions, history, signs, symptoms, and various pathogens (bacteria, fungi, viruses, viroids, nematodes, and parasitic plants) associated with plant pathology.

Plant Pathology

The study of organisms and environmental factors that cause disease in plants, the mechanisms of disease induction, and methods for prevention, control, and damage reduction.

Pathos

A Greek term meaning 'suffering,' forming the root of 'pathology' to describe the study of plant suffering.

Etiology

The study of the nature and cause of plant disease as part of Plant Pathology as a science.

Plant Pathology as an Art

The application of science to diagnose diseases, assess and forecast outbreaks, and recommend control measures.

Heinrich Anton de Bary

A German botanist and mycologist known as the Father of Plant Pathology and Mycology; he studied the life history of fungi and identified Phythopthora infestans as the cause of potato late blight.

Phythopthora infestans

A water mold that causes potato late blight, thriving in temperatures between $4$ and $29\,^\circ\text{C}$.

Physiogenic disease

A disease caused by non-living or inanimate agents, such as environmental factors.

Plant Disease (Agrios, 1998)

Any malfunctioning of host cells and tissues resulting from continuous irritation by a pathogen or an environmental factor leading to symptoms.

Disease Triangle

The conceptual model showing that disease results from the interaction of a Susceptible Host, a Virulent Pathogen, and a Favorable Environment.

Disease Pyramid

A conceptual model documenting the interaction between a Susceptible Host, Virulent Pathogen, Favorable Environment, and a Vector.

Inoculum

The pathogen or any part of the pathogen that lands on and can create infection in the host.

Incubation Period

The time interval between inoculation and the appearance of disease symptoms.

Latent Infection

A state in which a host is infected by a pathogen but does not exhibit any symptoms.

Saprophyte

An organism that lives on dead organic or inorganic matter, such as Pleurotus ostreatus (oyster mushroom).

Facultative saprophyte

An organism that is ordinarily a parasite but has the ability to live as a saprophyte, such as Taphrina deformans.

Virulence

The quantitative amount of disease that a specific pathogen isolate can cause in a group of plants.

Disease resistance

The inherent ability of an organism to overcome the effects of a pathogen to any degree.

Tolerance

The ability of a plant to withstand severe pathogen effects without experiencing a significant reduction in yield.

Symptom

A manifestation or expression of a plant as a result of a disease, such as mosaic, root-knot, or blight.

Sign

The actual pathogen or a part of the pathogen found on a host plant, such as spores, bacterial ooze, or sclerotia.

Systemic Symptoms

Disease reactions expressed by a greater part of or all of the plant, such as dwarfing, wilting, or yellowing.

Secondary Symptoms

Physiological effects of a disease appearing on distant and uninvaded organs, such as those caused by root knot of tomato (Meloidogyne incognita).

Histological symptoms

Internal abnormalities in cell content or size that require dissection and microscopic examination to identify.

Hypertrophy

Overdevelopment of plant organs due to an abnormal increase in the size of cells.

Hyperplasia

An abnormal increase in the number of cells, leading to overdevelopment or gall formation.

Haustorium

An absorbing organ of a fungus that penetrates a host cell without penetrating the plasma membrane.

Sclerotium

A hard, compact resting body composed of fungal hyphae.

Apothecium

An open, cup-like fruiting body containing asci.

Koch’s Postulates

A four-step criteria (Association, Isolation, Inoculation, Re-isolation) used to confirm the identity of a causal agent of a disease.

Ozone ($O_3$)

The most destructive air pollutant; produced by automobile exhausts and lightning, it enters through stomata to cause stippling and chlorosis.

Peroxyacyl nitrates (PANs)

Air pollutants from gasoline vapors and ozone that cause bronzing and silvering in the lower leaves of succulent plants.

Hemileia vastatrix

The causal agent of coffee rust, which devastated coffee production in Ceylon (Sri Lanka) and Batangas, Philippines.

Cadang-cadang

A slowly progressive disease of coconut palms caused by a viroid, resulting in small nuts and the eventual death of the growing bud.

Rice tungro

A viral disease caused by RTSV and RTBV, transmitted by the leafhopper Nephotettix virescens.

Mycotoxins

Toxic substances produced by storage molds, such as aflatoxin produced by Aspergillus flavus, which can cause liver cancer.

Plasmids

Extracellular, closed, circular genetic components in bacteria that are self-replicating and may enable new characteristics.

Transduction

The transfer of genetic material from one bacterium to another by means of a bacteriophage.

Hydathodes

Pores at the leaf margin continuous with the xylem through which bacteria like Xanthomonas campestris can enter a plant.

Plasmodiophoromycota

A phylum of endoparasitic slime molds, including Plasmodiophora brassicae, which causes clubroot of crucifers.

Oomycetes

Fungal-like protists with cell walls made of cellulose and glucans, including the orders Saprolegniales and Peronosporales.

Chytridiomycota

The only members of Kingdom Fungi that form motile cells (zoospores) with a single posterior flagellum.

Ascomycota

Sac fungi that produce sexual spores (ascospores) within an ascus; the sexual stage is called the teleomorph.

Basidiomycota

Club and mushroom fungi that produce sexual basidiospores externally on a basidium.

Capsid

The protein coat of a virus that protects its nucleic acid and facilitates cell-to-cell movement.

Persistent viruses

Viruses that require a latent period within an insect vector before the vector becomes capable of transmission for several days.

Viroids

Stable, free, 'naked' RNA molecules (250-375 base pairs) without a protein coat that infect plant cells.

Stylet

A retractable, protrusible structure in the mouth of a nematode used for puncturing plant cells and withdrawing contents.

Stomatostylet

A hollow nematode stylet with a distinct cone, shaft, and knobs, found in the Order Tylenchida.

Amphimixis

A mode of nematode reproduction that requires males for fertilization.

Parthenogenesis

A mode of reproduction where only females are produced from unfertilized eggs, and offspring are clones of the female.

Hemiparasites

Parasitic higher plants that contain chlorophyll but lack roots, depending on the host for water and minerals (e.g., witchweed, mistletoe).

True parasite

Parasitic higher plants with little or no chlorophyll and no roots, entirely dependent on the host for sustenance (e.g., dodder, broomrapes).