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Final lecture exam
New terms for Final
168
Pathology
Undergraduate 4
12/06/2009

Additional Pathology Flashcards

 


 

Cards

Term
Damping-off
Definition

Destruction of seedlings near the soil line, resulting in the seedlings falling over on the ground

Term
Hyphae
Definition

Individual strands of a mass of mycelium

Term
Acervulus
Definition

A conidium-bearing fruiting structure associated with many anthracnose diseases

Term
Enzyme
Definition

A protein produced by living cells that can catalyze a specific organic reaction

Term
Monocyclic Disease
Definition

Having one cycle per season

Term
Polycyclic
Definition

Completes many (life or disease) cycles in one year

Term

Rust spore stages

 

 

Teliospore

Definition

The sexual, thick-walled resting spore and smut fungi

Term

Rust spore stages

 

 

Basidiospore

Definition

A sexually produced spore borne on a basidium

Term

Rust spore stages

 

 

Spermatia

Definition

The male gamete or gametangium of rust fungi

Term

Rust spore stages

 

 

Aeciospores

Definition
Which on infection produce more dikaryotic mycelium that this time forms uredia
Term

Rust spore stages

 

 

Urediospores

Definition

Which also infect and produce either more uredia and uredospores or, near host maturity, telia and teliospores

Term
Smut
Definition

A disease caused by a smut fungi (Ustilaginales) characterized by masses of dark, powdery and sometimes odorous spores.

Term
Nematodes
Definition

Generally microscopic, worm-like animals that live saprophytically in water or soil, or as parasites of plants and animals

Term
Nematode Orders Common In Soil
Definition
  1. Rhabditida (buccal cavity)
  2. Dorylaimida (odontostylets)
  3. Tylenchida (stomatostylets)
Term
Nematodes that have a buccal cavity for a mouthpart are usually                 while nematodes with a stylet for a mouthpart are                    
Definition
  1. Saprophyte
  2. Parasite
Term
Stomatostylet
Definition

Are hollow spears associated with tylenchoids

Term
Odontostylets
Definition

Are solid, tooth-like structure associated with dorylaims

Term
Meloidogyne spp.
Definition
Root Knot Nematode
Term
Heterodera spp.
Definition
Cyst Nematode "Ground Pearls"
Term
Aphenlenchoides
Definition
Foliar Nematode
Term
Trichodorus
Definition
Stubby Root Nematode
Term
Meloidogyne spp.
Definition
  • Stomatostylet
  • Endoparasite
  • Prefers high temps
  • Mature female is pear-shaped
  • lays eggs externally
  • Galls due to growth regulators/"giant" cells
Term
Heterodera spp.
Definition
  • Stomatostylet
  • Endoparasite
  • Relatively narrow host range
  • Mature females are lemon-shaped
  • lays eggs within bodies
  • readily recognized on roots (pear-like females)
Term
Aphenlenchoides
Definition
  • Stomatostylet
  • Endoparasite
  • Causes langular lesions on leaves
Term
Trichodorus
Definition
  • Odontostylet
  • Ectoparasite
  • wide host range
  • transmits certain viruses, including (corky ringspot)
  • impedes root tip development
  • Dorylaims in the genus Trichodorus transmit the tobravirus, tobacco rattle, which commonly infects potatoes, causing "corky ringspot" in Hastings, Florida
Term
Gregor Mendel
Definition

He is known as the "father of modern genetics", was inspired by both his professors at University and his collegues at the monestary to study variation in plants

 

Between 1856 and 1863, he cultivated and tested some 29,000 pea plants

 

This study showed that one in four pea plants had purebred recessive alleles, two out of four were hybrid and one out of four were purebred dominant.

 

His experiments brought forth two generalizations

  • The Law of Segregation
  • The Law of Independent Assortment

These late became know as                   laws of inheritance

Term
Methyl Bromide
Definition
is a gas, still used in certain places to control soil-borne pathogens and is being phased out because it erodes away the earth's ozone layer
Term
Mercury
Definition
in 1913, organic mercury compounds were introduced as seed treatments, and such treatments were routine until the 1960's when all mercury-containing pesticides were banned because of their toxicity
Term
Mildews (Downy and Powdery)
Definition

A fungal disease of plants in which the mycelium and spores of the fungus are seen as a whitish growth on the host surface

Term
Mites
Definition
  1. Eriophyids
  2. Tetranychids
  3. Tarsonemids
Term
Eriophyids
Definition
a type of mite capable of transmitting certain viruss and, in many cases, causes virus like symptoms in plants by producing toxic saliva
Term
Tetranychidae
Definition
spider mites (very high populations)
Term
Tarsonemidae
Definition
broad mites (lower populations)
Term
Mollicutes
Definition

Wall-less mycoplasma-like bodies in the phloem of plants exhibiting yellows and witchs' broom symptoms.

 

Diseases caused by mollicutes appear as stunting of plants, yellowing or reddening of leaves, proliferation of shoots and roots, production of abnormal flowers, and eventual decline and death of plant

 

Term
Mycelium
Definition

The hypha or mass of hyphae that make up the body of a fungus

Term
Ozone Damage
Definition
  • Source: Automobile exhausts and other internal combustion engines (released NO2 combines with O2 in sunlight to from O3). From stratosphere. From lightning, from forests
  • Susceptible plants: expanding leaves of all plants, especially tobacco, bean, cereals, alfalfa, petunia, pine, citrus, and corn
  • Symptoms: Stippling, mottling, and chlorosis of leaves, primarily on upper surface. Spots are small to large, bleached white to tan, brown, or black
  • Remarks: Enters through stomata. It is the most destructive air pollutant to plants. A major component of smog
Term
Plant tissue culture
Definition
  • (high cash value prohibitive for all but the most expensive crops, usually ornamentals; however use is limited because of expense.
  • Tissue culture of disease-resistant plants is particularly useful with clonally propagated plants such as strawberries, apples, bananas, sugar cane, cassava, and potatoes
Term
Primary cycle
Definition
  • (infects only once)

 

  • The overwintering or oversummering pathogen, or its spores that cause primary infection
Term
Plasmogamy
Definition
  • Is a stage in the sexual reproduction of fungi.
  • In this stage, the cytoplasm of two parent mycelia fuse together without the fusion of nuclei, as occurs in higher terrestrial fungi
  • After plasmogamy occurs, the secondary mycelium forms. The secondary mycelium consists of dikaryotic cells, one nuclues from each of the parent mycelia
Term
Quarantine
Definition

Control of import and export of plants to prevent spread of diseases and pests

Term
Robigus
Definition
"god of rust"
Term
Secondary cycle
Definition

(infects more than once) inoculum produced by infections that take place during the same growing season

Term
Sori
Definition

a compact mass of spores or fruiting structure found especially in rusts and smuts

Term
Soybean Rust
Definition
  • Is caused by the Basidiomycete fungus Phakopsora pachyrhiza

 

  • Leaves with tan and reddish brown lesions as they appear macroscopically in the field
Term
Sooty Molds
Definition
a sooty coating on foliage and fruit formed by dark hyphae of fungi that live in the honeydew secreted by insects such as aphids, mealybugs, scales, whiteflies
Term
Sporodochium
Definition
a fruiting structure consisting of one or more cells; in function, it is analogous to the seed of green plants
Term
St. Anthony's Fire
Definition

is known today as ergotism and is the result of people and animals consuming grain coming from cultivated cereals and wild grasses infected with one or several ergot producing fungi.

 

Ergot (from the French "argot," which means a spur)

 

is the fruting structure produced by Claviceps purpurea and related fungi in place of the plant and contaminates the grain after harvest

Term
Teliospores
Definition

the sexual, thick walled resting spore of rust and smut fungi

Term
Ti plasmid
Definition
  • Is a circular plasmid that often, but not always, is a part of the genetic equipment that Agrobacterium tumefaciens and Agrobacterium rhizogenes use to transduce its genetic material to plants.

 

  • The                  is lost when Agrobacterium is grown above 28C
Term
T. Toxin
Definition
is produced by race T of C. heterostrophus (Bipolaris maydis), the cause of southern corn leaf blight. Race T, indistinguishable from all other C. heterostrophus races except for its ability to produce the T toxin, appeared in the US in 1968
Term
Viricides
Definition
Chemical agent that kills viruses
Term

Nuclear Conditions

 

Basidiomycete

Definition

All rusts are basidiomycetes

 

Dikaryotic mycelium 1N+1N i.e. plasmogamy not karyogamy

Term

Nuclear Conditions

 

 

Ascomycete (and most Deuteromycete)

Definition
Haploid Mycelium (1N)
Term

Nuclear Conditions

 

 

Zygomycetes

Definition
Haploid mycelium (1N)
Term

Nuclear Conditions

 

Oomycetes

Definition
Diploid mycelium (2N)
Term
Aluminum mulches (thwarting virus spread) (solarization)
Definition
  • Many plant viruses, such as cucumber mosaic virus, are brought into crops, such as peppers, by airborne aphid vectors. If reflectant aluminum or black, whitish-gray, or colored polyethylene sheets are used as mulches between the plant rows in the field, incoming aphids, thrips, and possibly other insect vectors are repelled and misled away from the field.
  • As a result, fewer virus-carrying vectors land on the plants and fewer plants become infected with the virus
Term
Bengal Famine (in relation to Monsoon season)
Definition
  • Normally, monsoons begin the 3rd week in June, becomes incessant July-August, and tails off towards the end of September.
  • November through December are rainless, humidity is low, and there are many "bright sunshine hours"

The bengal famine of 1942,

  • Unusually heavy rainfall in Sept.
  • Unusual and prolonged cloudy weather in Nov. with very low "Sunshine hours" and occasional rains
  • Higher minimum temps
Term
Downy Mildew
Definition

A plant disease in which the sporangiophores and spores of a fungus appear as a downy growth on the lower surface of leaves and stems, fruit, etc., caused by fungi in the family Peronosporaceae

  • Mostly cool or warm, but not hot conditions
  • Mostly Oomycetes
Term

Food Origins

 

Rice

Definition
Southeast Asia
Term

Food Origins

 

 

Wheat

Definition
(and barberry) in the Fertile Crescent (Israel, western Syria, Afghanistan)
Term

Food Origins

 

 

Corn

Definition
Central America
Term

Food Origins

 

 

Potatoes

Definition
In the Andes
Term
LSD
Definition

The best known of the Ergot alkaloids is lysergic acid diethylamide, the infamous LSD that was widely used as a hallucinogen by the hippie culture of the 1960's.

 

Depending on weather, the host plant (wheat, rye, barley, etc.) and the species of the ergot-forming fungus, the amount of ergot in the field and in the harvested grain may vary, as does the frequency and severity of the symptoms of ergotism

Term
Monoculture
Definition
Used in agriculture are usually strains that have been bred to be high yield and resistant to certain common diseases
Term
Powdery Mildew
Definition
  • Ascomycete
  • Prefer dry weather (worst out west) spores do not germinate in free water
Term
Rouging
Definition
(host eradication) (e.g. CMV in gladiolus) relates to pulling up a diseased plant and allowing it to die
Term

Rust

 

Autoecious

Definition
macrocyclic rusts, e.g. asparagus rust, complete their life cycles on a single host
Term

Rusts

 

Monoecious

Definition
  • (rusts only having one home) that is plants have separate male and female flowers on the same plant.
  • A plant population where the male and female organs are found in different flowers on the same plant
Term

Rusts

 

 

Macrocyclic

Definition
  • (long-cycled) means it has all the stages.
  • In addition to teliospores and basidiospores, spermatia (formerly known as pycniospores), aeciospores, and uredospores (also known as urediospores or urediniospores in that order)
Term

Rusts

 

 

Microcyclic

Definition
(short-cycled) rusts caused by fungi that produce only teliospores and basidiospores
Term
Avirulence gene (Avr)
Definition
  • The inability of a pathogen to infect a certain plant variety that carries genetic resistance
  • The avr genes make a pathogen avirulent, that is unable to induce disease on a specific variety of the host plant because their protein product warns the plant of impending attack by the pathogen and the host plant then mobilizes its defenses and blocks infection by the pathogen.
  • Avr protein: the protein coded for an avr gene, acting as an elicitor of defense reactions
Term
Abiotic disease
Definition

Nonliving, or caused by a nonliving agent

 

Examples: excess light, air pollution (ozone and acid rain), herbicide injury, Nutritional problems, physical damage (invertebrates- certain suctorial insects causing "hopper burn, galls. Also, damage caused vy Eriophyid and broad mites.

Term
Acervulus
Definition
  • A subdermal, saucer shaped, asexual fruiting body producing conidia on short conidiophores
  • A flat, open pad of short conidiophores growing side-by-side
  • The conidiophores develop from the underlying mass of somatic hyphae
Term
Agrobacterium tumefacians
Definition
  • These bacteria are rhizosphere and soil inhabitants
  • involves introducing T-DNA from its plasmid that induces a tumor (Ti-Tumor inducing gene) into the plant cell, and is hence termed "genetic recombination."
  • Discovered in 1890 by Erwin Smith
Term
Alternaria
Definition
  • Deuteromycete
  • Induces zonate lesions
  • Early blight, wide host ranges
  • can be controlled with UV absorbing film, in greenhouses (preventing sporolation)
Term
Alternaria
Definition
Early blight
Term
Anthracnose
Definition
  • Colletotrichum, Gloeosporium (Deuteromycetes) result in open basin-like sores
  • The above two genera are Anamorphs (asexual), and most commonly encountered among the anthracnose fungi
  • Teliomorphs (sexual) are less common (Glomerella, perithecium)
  • Primary cycle involves conidia and plant debris
Term
Angiosperms
Definition

Kingdom Planta

 

Any flowering plant; plants that produce seeds enclosed within a carpel (a carpel is the ovuliferous organ of the flower; a simple pistil or one of the segments of a compound pistil. (ovary, style, stigma)

Term
Aphanomyces
Definition

Oomycete (Chromistic algae)

 

  • Seedling disease (Root Rot)
  • In new seedlings, symptoms often appear in the form of stunted, yellow plants with overall poor root development and few lateral roots
  • Most severe in wet conditions
Term
Apical Meristem
Definition

A meristem (growing region) at the tip of a plant shoot or root that produces auxin and causes the shoot or root to increase in length.

 

Growth that originates in the apical meristem is called primary growth. (this area is free of viruses (not present), allowing for tissue propagation, but very expensive.)

Term
Arithmetic Progression
Definition
Will result in a linear line on a graph
Term
Sigmoid Progression
Definition
  •                curve will result in three important points on a graph
  1. Lag Phase
  2. Exponential Phase or logarithmic phase
  3. Deceleration phase

 

Term
Lag phase
Definition
The initial growth phase, during which cell number remains relatively constant prior to rapid growth
Term
Exponential or logarithmetic phase
Definition
The steepest slope of the growth curve-- the phase of vigorous growth during which cell number doubles every 20-30 minutes for E. coli
Term
Deceleration Phase
Definition
This is when the growth rate is negative, resulting in a decline
Term
Aspergillus flavus
Definition

Produces aflatoxin, a deadly carcinogen. Favors dry conditions

 

In peanuts, dry conditions result in peanuts cracking (outer shell), and provides a pathway for the pathogen to enter.

 

Similar to Penicillium spp. but Penicillium are blue-green, deuteromycetes, this prevails (mold and blue cheese)

Term
Aspergillus flavus
Definition
Aflatoxin
Term
Beijerinck (Martinus)
Definition
  • Researcher isolated and identified new types of bacteria from soil, particularly autotrophic bacteria, that use inorganic chemicals as nutrients and as a source of energy.
  • The earliest indications of the biological nature of viruses came from studies in 1898 by this Dutch scientist                  .
  • Considered founder of virology
  • Termed viruses as a "contagious living fluid"
Term
Bengal Famine
Definition

Caused by Helminthiosporium oryzae (brown spot of rice), 1942 and 1943. Cool, wet conditions were present during disease outbreak.

 

The crop was ruined and the result was widespread famine.

 

Longer rain period with less sunshine

 

Over 2 million people died because of this.

Term
Bipolaris-C. heterostrophus
Definition

Sexual stage with filamentous ascospores

 

  • Bipolaris (formerly Helminthosporium) maidis (Deuteromycete name) - "Southern corn leaf blight" Anamophic, affected kernels are covered with black, felty mold, and cobs may rot or, if the shank is infected early, the ear may be killed prematurely and drop
  • Cochliobolus heterostrophus (ascomycete name) (teliomorph)
Term
Botrytis
Definition

Gray mold

Deuteromycete

Term
Botrytis
Definition
  • Most common disease of greenhouse crops and elsewhere
  • Favors cool, humid conditions, gains ingress thru injury thru decaying flower petals or damaged leaves and then advances towards healthy tissues.
  • Produces gray mycelium, conidia, and FLAT sclerotia
Term
Buccal Cavity
Definition
Invagination of the mouth of certain nematodes (Rhabdita)-- now pathogenic, NO stylet
Term
Chestnut Blight
Definition
Endothia parasitica  Cryphonectria parasitica
Term
Chestnut blight
Definition
  • Not a true vascular wilt, rather it girdles the bark of its host instead
  • Overwinters in the host tissue, during growing season, suckers are produced, but they subsequently become infected and die back
  • Fungus eats vascular tissues
Term
Cleistothecium
Definition

"closed like a vase," "Tomb-like" circular structure=black ball. Some have hook-like structures around the "ball," while others have "myceloid appendages."

 

Produced by the sexual stage of powdery mildews (Oidium-asexual), Phyllactinia- is the teleomorph

 

The structure houses ascospores

Term
Cercospora
Definition
  • Deuteromycete
  • Many species, many hosts, both dicots and monocots
  • Lesions often have dark borders and tan centers
  • Unique conidia shape
Term
Cercospora
Definition
Leaf spots
Term
Claviceps purpurea
Definition
  • Ergot- cannot be eaten, derivative is LSD, this is thought to be a symbiotic relationship, bacause it prevents herbivory
  • Ascospores are filamentous (more surface area), spores are shot out, copper supplements reduce the incidence of the pathogen
  • Copper deficient soils allow for flowers to remain open longer (greater pathogen window)
Term
Choanephora
Definition
  • Unique sporangium (modified), with spores solitary on structure. Do not confuse with Oomycota, it is actually Zygomycota.
  • Coenocytic mycelia (male and female reproductive structures), virtually indistinguishable from each other (verses Oomycota male: antheridium, and female oogonium).
  • The mycelia produce a zygospore, when male and female mycelia come together. (Undergoes plasmogamy and karyogamy) (do not confuse this with zoosporangium (Oomycota) which contains zygospores (flagellate spores))
Term
Coconut Lethal Yellowing Phytoplasma
Definition
  • Phytoplasmas are pleomorphic, meaning "malformed looking."
  • Lack cell walls and are susceptible to tetracycline

 

Term
Coffee Rust
Definition
Helmileia vastatrix
Term
Coffee Rust
Definition
  • Coffee is Ethiopian in origin, with its worst occurrence of disease in Sri Lanka.
  • Probably classified as microcyclic (not all cycles of rust life cycle are present) vs. macrocyclic (wheat rust- they have all the stages)
  • presumed heteroecious (two homes)
  • caused the english to become tea drinkers
Term
Colletotrichum
Definition
  • Deuteromycete
  • An anthracnose disease
  • Can be determined by the presence of hairs around the acervulus. Open basin-like sores=symptoms.
  • Signs= acervuli with spores
  • Anamorphs are the most common (Colletotrichum/Gloesporium)
  • An asexual form of perithecium (sexual fruiting structure), is a pycnidium which contains conidia versus the perithecium which contains ascospores (both are "flask-shaped")
Term
Ustilago maidis
Definition

Corn Smut

 

Basidiomycetes (restricted to the poaceae-affecting the grains)

Term
Ustilago maidis
Definition
  • Basidiomycetes
  • Very unique (smuts in general)
  • Teliospores, 2n (nuclear condition), germinate to for basidia)
  • Basidia form basidiaspores, which are 1n
  • The basidiospores that infect the host are 1n
  • Hyphal anastomoses results in a union of 1n+1n
  • Galls form, mycelium occupies hyperplastic cells
Term
Cronartium quercuum
Definition
Fusiform rust of pines and oaks
Term
Cronartium quercuum
Definition
  • attacks particularly slash and loblolly pine; however, disease does not spread from pine to pine
  • Oaks are equivalent of wheat (wheat rust life cycle)
  • Pines are equivalent to barberry
  • One cycle a year due to the presence or non-presence of juvenile tissues (needed to infect). Causes malformed protuberances (galls) on the pines
Term

Disease control principles

 

Exclusion

Definition
  • relates to the pathogen-keep it away (Quarantine-citrus canker story, coconut lethal yellowing, Dutch elm disease- realize the points of the examples
  • Separate growing areas (seedling/adult), grow where pathogen cannot survive.
  • Use certified seed
Term

Disease Control Principles

 

Eradication

Definition

relates to the pathogen-- eliminate the pathogen if it enters the area.

 

Methods:

  1. Rouging (pulling up infected plants, and allow them to die)
  2. Eliminate alternative hosts (rusts)
  3. Crop rotation
  4. sanitation
  • Biological Control (trap crops, parasitism)
  • Physical control (heating the soil, cooling your product (cut flowers)
  • Chemical control for pathogens

 

Term

Disease Control Principles

 

 

Protection

 

Definition
Relates to the host--barricade the suspect, comes down to prevention measures. Chemical prevention measures=mercury for instance in terms of seed protection
Term

Disease control principles

 

 

Genetic Resistance

Definition
relates to the host-- render your crop insusceptible. Using vertical or horizontal resistance methods, selecting for resistant varieties
Term
Doubling time
Definition
T2=70/Percent
Term
Dutch elm Disease
Definition
Ophiostoma ulmi
Term
Dutch Elm Disease
Definition
  • This pathogen managed to get to America (despite quarantine) on Bark-covered wood used as lumber
  • The fungus overwinters in the beetle galleries, and when the beetles emerge, they spread the pathogen throughout their galleries
  • True vascular wilt
  • Vascular wilt pathogens primarily infect the XYLEM
  • Scolytis multistriatus- the introduced beetle vector
  • Cut off the wood, deprive the fungus. the beetle attack dead wood
Term
Ergotism
Definition
Claviceps purpurea
Term
Ergotism
Definition
  • Is an example of a mycotoxicosis caused by food and feed made extremely unhealthy by mycotoxins.
  • Several mycotoxins are proven carcinogens, may disrupt the immune system, and may retard the growth of humans or animals that consume them
  • Causes vasoconstriction, and can result in limbs being removed/dying
Term
Erwinia amylovora
Definition
Fire blight of apple and pears
Term
Erwinia amylovora
Definition
  • It is a rod-shaped bacterium, has peritrichous flagella, and requires nicotinic acid as a growth factor. Serological tests help identify it
  • Ants help the initial dissemination (ants are present all around the tree) (ooze is sweet and sticky) where it is subsequently taken up by bees,who pass it to uninfected trees/plants by flower-to-flower movement.
  • Focus on ooze, remove dead branches. Bees spread it exponentially. Sanitation
Term
Erwinia trecheiphila
Definition
Cucumber wilt
Term
Erwinia tracheiphila
Definition
  • vascular disease
  • Sign is ooze
  • Survives only a few weeks in infected plant debris. However, it survives over winter in the intestines of striped cucumber beetles, and spotted cucumber beetles, in which it hibernates
Term
European Barberry
Definition
The "true alternate host" of wheat rust
Term
Exobasidium
Definition

Bahavior is similar to Taphrina deformans (Peach Leaf Curl), and is virtually indistinguishable in accordance to symptoms and signs

 

  • It is a basidiomycete VERSUS T. deformans an ascomycete
  • Both require juvenile tissues, more prevalent in northern climates, because juvenile tissue is present much longer
  • Both are monocyclic
  • Leaves show bright red/green "curls"
Term
Fusarium oxysporum
Definition
  • Ascomycetes (when sexual)
  • Anamorph
  • fusarium wilts (vascular wilts)
  • species specific as noted by "forma specialis."
  • narrow host range
Term
Fusarium solani
Definition
  • Ascomycetes (when sexual)
  • wide host range
  • "damping-off"
  • (asexual stages=macroconidia, microconidia, chlamydospores)
  • macroconidia contain chlamydospores (single-celled conidia with thick covering)
  • Microconidia are solitary conidia
  • Purplish mycelium
Term
Gene (elicitor/pathogen, response/host)
Definition
Pathogen carries the elicitor gene (may not be present, therefore no response is given by the host), Host has a corresponding gene that recognizes the pathogen (again, not always) and responds (akin to antibody/antigen recognition). "Lock and key"
Term
Geometric progression
Definition

In mathematics it is also known as a geometric sequence, is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed non-zero number called the common ratio.

 

For example, the sequence 2,6,18,54... is a geometric progression with a common ratio of 3. Similarly 10, 5, 2.5, 1.25,... is a geometric sequence with common ratio of 1/2. The sum of the terms of a geometric progression is known as a geometric series.

Term
Gloeosporium
Definition
  • Compare with Colletotrichum.
  • BOTH are anthracnose diseases, Gloeosporium lacks the hairs present around the acervulis, which is an indicator of Colletotrichum (hairs)
  • Both are anamorphs
Term
Guignardia bidwellii
Definition
Black rot of grape
Term
Guignardia bidwellii
Definition
  • Sexual stage is termed "saprophyte"
  • While anamorphic stage (parasite-like) is much less effective in its spread (an ooze ermerges from the pycnidium to disperse conidia)
  • The sexual stage disperses ascospores (perithecium) by "shooting them out"
  • Much more effective
Term
Haustorium
Definition
(dodder and powdery mildew)
Term
Haustorium
Definition
A simple or branched projection of hyphae into host cells that acts as an absorbing organ (anchor)
Term
Karyogamy
Definition

The fusion of 2 (usually haploid) nuclei during sexual reproduction, resulting in the formation of a diploid zygote.

 

This occurs immediately after plasmogamy  (the fusion of cytoplasm between two cells, usually gametes or protoplasts. Plasmogamy occurs shortly before karyogamy.)

Term
Kudzu Vine (related to soybean rust topic)
Definition
  • Not a true alternate host, but it enables Soybean rust (Asian soybean rust, Phakopsora pachrhizi) to persist throughout the winter in the southern United States.
  •               cannot survive cold winters, but it is good at hiding.
  •               was originally imported as a high protein forage food, but since it has become a very noxious weed.
  • Some              show immunity, resistance, and no-resistance.
  • Immunity and resistance may not always be present in                  , because of changes in the pathogen may negate immunity/resistance.
Term
Logarithmic Phase
Definition
(related to Sigmoid curve, the "growth phase")
Term
Mediterranean East Wind
Definition
Relates to the spread of Wheat rust, in the middle east. Ancient Greece/Rome
Term
Monilinia fructicola
Definition
Brown rot of stone fruits
Term
Monilinia fructicola
Definition
  • Symptoms- moist soft rots, decay
  • Signs- Sporodochia with conidiam apothecia, mummies
  • Life Cycles- Primary (one): perithecia with asci

Secondary (many): sporodochia with conidia (especially fruits)

  • Transition: Fruits mummify into a sclerotium-like structure
Term
Oidium
Definition
  • Anamorphs
  • Powdery mildews (Ascomycetes)
  • Hyphae superficial, send haustoria into epidermis, but do not penetrate host further.
  • Conidia are secondary inocula
Term
Penicillium
Definition

Blue and Green molds

Deuteromycete

Signs: usually blue or green colored mycelium

Term
Plasmodiophora brassicae
Definition

Myxomycete, a protozoan plant pathogen

 

Causes clubroot; the causal agent is an obligate parasite

Term
Plamodiophora brassicae
Definition
  • Symptoms: are conspicuous root gall, no necrosis
  • Very restricted host range
  • Produces intracellular plasmodium
  • Plasmodium breaks up into zoospores
  • Require acidic soils; can be controlled by raising pH to about 7.2 or higher
Term
Plasmopara viticola
Definition
  • Downy mildew of grape
  • Oomycete
Term
Puccinia graminis
Definition
  • causing severe and often catastrophic diseases on numerous hosts such as the (stem rust of wheat and all other small grains)
  • Also causes rust diseases on field crops such as cotton
Term
Pythium spp.
Definition

Oomycete (Chromistic algae)

 

Symptoms: Below ground (root rot, stem cankers)

Above ground (stem cankers, foliar blights)

 

Signs: hyphae/mycelium (coenocytic)

 

Zoospores/sporangia

 

Sexual stage common: Oospores, Oogonia, Antheridia

Term
Ralstonia (Pseudomonas) solanacearum
Definition
  • Southern bacterial wilt
  • Vascular wilt caused by bacteria
  • Mosty tropical
  • Survives in plant debris, tubers, wild hosts
Term
Rhizoctonia solani
Definition

Basidiomycetes

 

Wide host range

 

Symptoms: below ground (root rot, stem cankers)

Above ground (stem cankers, foliar blights)

 

Signs: Hyphae/Mycelium (no spores, septate)

 

No asexual spores

 

sclerotia

 

Sexual stage not common

Term
Rhizopus, Mucor
Definition
  • Zygomycete molds or bread molds 
  • Zygomycete
  • Signs: rank, translucent mycelium with black sporangia
Term
Sclerotinia sclerotiorum
Definition

Cotton rot

 

Ascomycete

 

Associated with St. Andrew's Fire

 

Signs: white colored mycelium with "rat-turd" sclerotia

 

Most aggressive under cool, moist conditions

Term

Sclerotinia sclerotiorum

Compare and Contrast

Definition
  1. Rhizoctonia solani and Sclerotium rolfsii (sclerotia are formed, but no conidia)
  2. Monilinia fructicola (apothecia are produced)
  3. Opposite of Sclerotium rolfsii in that it thrives in cold weather
Term
Sclerotium rolfsii
Definition
  • (like Rhizoctonia)
  • Deuteromycete
  • Very wide host range
  • Mycelium white (no 90 degree branching)
  • Truly a hot weather pathogen
  • Asexual stage without spores
  • Sexual stage (Basidiomycete)
Term
South American Rubber Tree Blight
Definition
Microcyclus ulei
Term
South American Rubber Tree Blight
Definition
  • A fungal leaf spot and very devastating
  • Precludes consolidation plantings of rubber trees in Amazonia
  • Consolidated planting of rubber trees is successful in Southeast Asia due to effective quarantine practices
Term
Taphrina deformans
Definition

Causes peach leaf curl

 

  • Ascomycete
  • Brightly colored, rubbery galls; no necrosis
  • No ascocarp
  • Requires juvenile tissues, abetted by cool weather
Term
Tobravirus
Definition

Tobacco rattle virus

  • ssRNA, bi-partite, rigid rod
  • Nematode-transmitted (the dorylaim, trichodorus)
  • Very wide host range
Term
Tropical soda apple
Definition
This is the weed that is susceptible to virus infection, Tobacco Mosaic Virus, and the result is death for the Tropical Soda Apple (VERY unique for viruses)
Term
Ustilago maydi
Definition

Corn Smut

 

Mexican tacos

 

Teliospores (2N) germinate to form basidia

 

Basidia from basidiospores (1N)

 

Basidiospores infect hosts (1N)

 

Hyphal anastomoses results in (1N+N)

Term
Venturia inaequalis
Definition

Apple scab

 

Symptoms: dry lesions

Signs: acervuli with spores

Life cycles: primary (one) Perithecia with asci (2-celled ascospores/disease forecasting)

Secondary (many): Acervuli with conidia

Transition: parasite become saprophyte

Term
Verticillium albo-atrum
Definition

causes wilt in cotton

 

  • Attack hundreds of kinds of plants, causing wilts and losses of varying severity
  • All vascular wilts have certain characteristics in common
  • The leaves of infected plants or of parts of infected plants lost turgidity, become flaccid and lighter green to greenish yellow, droop, and finally wilt, turn yellow then, brown, and die
Term
Xanthomonas axonopodis pv. citri
Definition
Citrus canker
Term
Xanthomonas axonopodis pv. citri
Definition
  • is one of the most feared of citrus diseases affecting all types of important citrus crops.
  • It causes necrotic lesions on fruit, leaves, and twigs.
  • Losses are caused by reduced fruit quality and quantity and premature fruit drop.
  • The disease is endemic in Japan and Southeast Asia, from where it has spread to all other citrus producing continents except Europe.
Term
Xanthomonas campestris pv. citrumelo
Definition
  • Citrus spot
  • results in raised lesions, and was not particulary damaging
Term
Juvenile (versus mature tissue) in relation to susceptibility to disease
Definition
would be more succulent, resulting in softer tissue, which could make it more susceptible to attack by insects, etc.
Term
Oxalates
Definition
  • This was produced by Sclerotium sclerotinium (oxalate acid)
  • Oxalates deficient fungi were slower to infect, but still caused infection, showing that multiple chemical routes of infection may be present when dealing with this pathogen.
  • A suite of enzymes with the ability to degrade the cell wall of its host
Term

Resistance

 

Vertical Transmission

Definition
breeding for naturally occuring varieties that show resistance to a pathogen, and then isolating that variety and using that variety for future crop production (or ornamental production, etc)
Term

Resistance

 

Horizontal Transmission

Definition

This involves taking the current crop and finding a different species that shows no vulnerability to the pathogen and cross breeding them.

 

The resultant progeny would be isolated and evaluated for the gene that allows for resistance. This progeny (F1) would be bred back into the original susceptible line, and they would evaluate for gene transfer to their progeny (original strain + F1 cross).

Term
Southern Corn Leaf Blight
Definition

Bipolaris (formerly Helminthosporium) maidis (Deuteromycete name)

 

Cochliobolus heterostrophus (Ascomycete name)

  • Sexual stage a perithecium with filamentous ascospores
  • Genetic recombination led to 1970's blight epidemic
Term
Texas Male Sterile cytoplasm
Definition
A widespread epidemic caused by a new race (Race T) of the southern corn leaf blight (Bipolaris) fungus occurred suddenly in 1970 on all corn hybrids containing the Texas cytoplasmic male sterility gene (used for efficient crossing and production of corn hybrids) and destroyed 15 percent of all corn produced in the US that year.
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