I have tried to use terminology to describe RRD that is both understandable yet not oversimplified. There are words that describe plant abnormalities rather precisely that come from the phytopathological literature.  Phtyo- (from the Greek phuton for plant) + pathology (the branch of medicine concerned with the cause origin, and nature of disease including the changes occurring as a result of disease).  Many RRD symptoms are seen on other plants and associated with other diseases so the words already exist.

The glossaries below may clarifiy words that are incompletely described in this work.
The glossary for the American Phytopathological Society is below


A large glossary from Cornell:


A glossary from Oregon State University Extension Service:


Pest Management Resource Centre in the UK has the following glossary that includes animal diseases:


The following shorter glossary is from L E. Browder at Kansas State:


Below is a glossary of terms used in this website:                                                

asymptomatic (adj.) - a condition inwhich a plant has infection but does not show visible symptoms (see latent infection) .

avoidance - principle of plant disease control in which crops are grown at times or locations where a particular pathogen is inactive or not present .

axil - the angle formed by the leaf petiole and the stem

axillary - pertaining to or placed within an axil

axillary bud - (syn. lateral bud) - bud that develops in the axil of a leaf

brooming - profuse branching of woody stems from single stem position

chlorosis - (adj. chlorotic) - a term which literally means "becoming green" but in plants refers to a
whitish or yellowish or abnormally light green discoloration resulting from a failure of chlorophyll
development, caused by disease or a mineral dificiency .

downy mildew - a plant disease in which the fungus appears as a downy growth on the host surface; caused by a member of the Oomycetes

ELISA - (acronym for Enzyme-Linked ImmunoSorbent Assay)  - a serological test in which the presence of a pathogen is detected by attaching an enzyme that produces a colored product to
one of the reactants to the particular pathogen .

endemic - native to a particular area resulting in a low and steady level of natural occurrence of disease.

epidemic - literally "among people", occurance of contagious disease spreading rapidly and extensively among many individuals in an area. (see epiphytotic) although literally refering to people, it is commonly used in reference to diseases affecting animal and plant populations other than humans.

epiphytotic - a general and serious outbreak of a disease in plants. epidemic is often used in its sted.

epinasty - abnormal, downward curling of a leaf, leaf part, or stem

fasciation  - malformation in stems or floral organs manifested as elongation in cross section and
flattening as if several stems were growing parallel to each other but still longitudinally attached.

graft - a method of plant propagation in which one transfers parts of one plant (budwood or - the scion) into close cambial contact with the root or trunk  of a different plant (the rootstock). In addition to its use for propagation, this is a way to transfer plant pathogens such as a virus from one plant to another.

graft transmission - transmission of a pathogen from one host plant to another through grafting from the diseased host with living tissue onto a healthy host.

immune - a trait of a plant which cannot be infected by a given pathogen (as compared to tolerant).

incubation period - the time after a vector has acquired a pathogen and before it can be transmitted

isolate (n.) - a culture or subpopulation of a microorganism separated from its parent population and
maintained in some sort of controlled circumstance;

isolate (v.) - the removal of a pathogen from a host so it can be grown in pure culture . A critical first
step toward developing an ELISA test.

Koch's postulates - the procedure used to prove the pathogenicity of an organism, i.e. its role as the
causal agent of a disease.  Koch's Postulates are:
       1. The specific organism should be shown to be present in all cases of animals suffering from
        a specific disease but shold not be found in healthy animals.

        2. The specific microorganism should be isolated from the diseased animal and grown in pure
    culture on artificial laboratory media.

        3. This freshly isolated microorganism, when inoculated into a healthy laboratory animal,
        should cause the same disease seen in the original animal.

        4. The microorganism should be reisolated in pure culture from the experimental infection.

  lapse rate - " The data strongly suggests that rose RRD is a "high lapse rate" disease (disease incidence falls off very rapidly with distance from the infection source" (Dr. A. Epstein Pers. Comm. 2001). This is from an e-mail from Dr. Epstein and explains their use of the term with which I had familiarity only in its meterological context.

latent - present but not manifested or visible - to lie hidden or concealed.

latent infection - a condition inwhich a plant has infection but does not show visible symptoms.  

latent period - the time period between infection and the first appearance of symptoms.

mosaic - disease symptom characterized by non-uniform coloration, with intermingled normal, light
green and  yellowish patches, usually caused by a virus; often used interchangeably with mottle

mottle - disease symptom comprising light and dark areas in an irregular pattern, usually caused by a virus; often used interchangeably with mosaic

necrosis - (adj. necrotic) - death of cells or tissue, usually accompanied by black or brown darkening

pathogen - A nonspecific term for any agent that causes disease, especially a microorganism such as a bacterium, fungus, virus or phytoplasm.

phyllody - a condition in which the floral part of the plant forms leaflike structures.

powdery mildew  - a white, powdery, superficial ascomycetous fungus that is an obligate parasite and generally is found only on one or a few closely related species of plants

rogue - the removal (and destruction of) individual plants that are diseased or abnormal, infested by
insects, or otherwise undesirable.

rose mosaic virus disease - a nonlethal, non contagious group of virus infections in roses that result in general failure to thrive and often show symptoms as mosaic of foliage.  They can only be transmitted through grafting, so are spread through poor cultural practices by rose producers.

rosette - disease symptom characterized by short, bunchy growth habit due to shortened internodes and no comparable reduction in leaf size

symptomatic - a condition inwhich a plant expresses specific abnormal traits that are normally associated with a specific disease.

tolerant - the ability of a plant to remain asymptomatic and grow normally after exposure to a particular pathogen. (as compared to immune).

witches' broom - a disease symptom characterized by the development of large numbers of accessory abnormal, massed, brushlike shoots originating at or need the same point.

yellows - any of various plant diseases, usually caused by fungi of the genus Fusarium or viruses of the genus Chlorogenus and characterized by yellow or yellowish discoloration and stunting of the host plant.

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