Pathology introduction

PLANT PATHOLOGYPLANT PATHOLOGY
INTRODUCTIONINTRODUCTION

Plants make up the majority of earthsPlants make up the majority of earths
living environmentliving environment
Plants are the only organisms that convertPlants are the only organisms that convert
the suns energy to foodthe suns energy to food
All animals including humans depend onAll animals including humans depend on
plants for foodplants for food
Plants as do people get “sick”Plants as do people get “sick”
The causal agents are similar to humanThe causal agents are similar to human

Disease causing organisms include;Disease causing organisms include;
VirusesViruses
BacteriaBacteria
FungiFungi
ProtozoaProtozoa
NematodesNematodes
Or unfavorable environmental conditionsOr unfavorable environmental conditions

Plant pathology is the study ofPlant pathology is the study of
microorganisms and environmental factorsmicroorganisms and environmental factors
that cause plant diseasethat cause plant disease
The way they workThe way they work
The way they are avoided or controlledThe way they are avoided or controlled
The cost of control must be less than theThe cost of control must be less than the
profitprofit
Environment friendly materials must beEnvironment friendly materials must be
usedused

A plant is considered healthy if it functionsA plant is considered healthy if it functions
to the best of its genetic abilityto the best of its genetic ability
When a plant function is interfered with byWhen a plant function is interfered with by
a microorganism or environmental factora microorganism or environmental factor
the plant is diseasedthe plant is diseased
The visible changes are the symptomsThe visible changes are the symptoms
Some pathogens affect only one variety ofSome pathogens affect only one variety of
plant while others affect many speciesplant while others affect many species

History of Plant DiseaseHistory of Plant Disease
The Romans were so aware of famineThe Romans were so aware of famine
they created a special rust god, Robigothey created a special rust god, Robigo
who was responsible to protect peoplewho was responsible to protect people
from faminefrom famine
These beliefs lasted about 2000 yearsThese beliefs lasted about 2000 years
The compound microscope was inventedThe compound microscope was invented
in the 1600’sin the 1600’s

CLASSIFICATION OFCLASSIFICATION OF
DISEASESDISEASES
Infectious diseaseInfectious disease

Diseases caused by fungiDiseases caused by fungi

Diseases caused by prokaryotes (bacteria &Diseases caused by prokaryotes (bacteria &
mollicutesmollicutes

Diseases caused by parasitic plantsDiseases caused by parasitic plants

Diseases caused by viruses and viroidsDiseases caused by viruses and viroids

Diseases caused by nematodesDiseases caused by nematodes

Diseases caused by protozoaDiseases caused by protozoa

Non Infectious diseasesNon Infectious diseases
Diseases caused by low or highDiseases caused by low or high
temperaturetemperature
Diseases caused by lack or excess soilDiseases caused by lack or excess soil
HH22OO
Diseases caused by lack or excess lightDiseases caused by lack or excess light
Diseases caused by lack of oxygenDiseases caused by lack of oxygen
Diseases caused by air pollutionDiseases caused by air pollution
Diseases caused by nutrient deficienciesDiseases caused by nutrient deficiencies
Diseases caused by mineral toxicitiesDiseases caused by mineral toxicities

Non infectious plant diseasesNon infectious plant diseases
Diseases caused by soil acidity orDiseases caused by soil acidity or
alkalinityalkalinity
Diseases caused by toxicity of pesticidesDiseases caused by toxicity of pesticides
Diseases caused by improper culturalDiseases caused by improper cultural
practicespractices

The Birth of Plant PathologyThe Birth of Plant Pathology
The fungus found on potatoes was firstThe fungus found on potatoes was first
described by Dr. C Montagne, a Frenchdescribed by Dr. C Montagne, a French
doctor with Napoleon’s armydoctor with Napoleon’s army
He shared his observation with Rev. M. J.He shared his observation with Rev. M. J.
Berkely who thought it might be connectedBerkely who thought it might be connected
with the diseasewith the disease
Dr. John Lindley, a rival did not believeDr. John Lindley, a rival did not believe
there was a connectionthere was a connection

Was the fungi the cause or the effect?Was the fungi the cause or the effect?
Grain was used as an export to raise $Grain was used as an export to raise $
Sir Robert Peel used the blight as anSir Robert Peel used the blight as an
excuse to repeal the protectionist tradeexcuse to repeal the protectionist trade
laws to import corn from America to feedlaws to import corn from America to feed
the starving Irish. It was called Peel’sthe starving Irish. It was called Peel’s
Brimestone” because the recipients wereBrimestone” because the recipients were
considered ungratefulconsidered ungrateful

During a 15 year period 1 million Irish died ofDuring a 15 year period 1 million Irish died of
disease and starvation and another 1.5 milliondisease and starvation and another 1.5 million
left to go to the U.S. or Canadaleft to go to the U.S. or Canada
The scientist of the time were unable to save theThe scientist of the time were unable to save the
crops but there came an understanding of plantcrops but there came an understanding of plant
diseasedisease
Anton deBary, a German Botanist performedAnton deBary, a German Botanist performed
experiments that proved the role of fungus in theexperiments that proved the role of fungus in the
blightblight

For 200 years people thought the diseaseFor 200 years people thought the disease
causing organisms were the result , not thecausing organisms were the result , not the
causecause
The theory of spontaneous generation wasThe theory of spontaneous generation was
abandoned for the germ theory in 1863abandoned for the germ theory in 1863
It was originally namedIt was originally named Botrytis infestansBotrytis infestans byby
Montagne but was changed toMontagne but was changed to PhytophthoraPhytophthora
infestansinfestans by deBary because he realized theyby deBary because he realized they
were not relatedwere not related

Phyto= plantPhyto= plant
Phthora =destroyerPhthora =destroyer
Phytophthora= plant destroyerPhytophthora= plant destroyer
Infestans=devastating infestationInfestans=devastating infestation
Usual microorganisms do not haveUsual microorganisms do not have
common names since only scientist talkcommon names since only scientist talk
about themabout them

Proof of pathogenicityProof of pathogenicity
Koch’s postulatesKoch’s postulates
The symptoms and any evidence of theThe symptoms and any evidence of the
pathogen in the diseases host are carefullypathogen in the diseases host are carefully
describeddescribed
The suspected pathogen is isolated from theThe suspected pathogen is isolated from the
host, a description is made.host, a description is made.
A healthy host is inoculated, describedA healthy host is inoculated, described
The pathogen is isolated and must be the sameThe pathogen is isolated and must be the same
as originalas original
When all four steps are complete= proofWhen all four steps are complete= proof

Even though the cause was discovered,Even though the cause was discovered,
they did not know how to treat itthey did not know how to treat it
The last major famine was 1916The last major famine was 1916
Copper was then known to protect cropsCopper was then known to protect crops
but it was needed to make bullets for thebut it was needed to make bullets for the
warwar
700,000 Germans died from starvation700,000 Germans died from starvation

Arrival of the potato in EuropeArrival of the potato in Europe
The potato was from the highlands ofThe potato was from the highlands of
South America’s, Lake TiticacaSouth America’s, Lake Titicaca
It was discovered by the SpanishIt was discovered by the Spanish
Conquistadors while looking for goldConquistadors while looking for gold
The crop dates back to 400 B.C.The crop dates back to 400 B.C.
The first potatoes reached Europe aboutThe first potatoes reached Europe about
15701570

New cultivars were developedNew cultivars were developed
The potato was resistant for a few yearsThe potato was resistant for a few years
Then the blight returnedThen the blight returned
The blight develops a new race to attackThe blight develops a new race to attack
each new cultivareach new cultivar
The boom and bust cycle is the resultThe boom and bust cycle is the result

Lessons from the potato famineLessons from the potato famine
The disease triangle, plant, pathogen,The disease triangle, plant, pathogen,
environmentenvironment
Disease
Susceptible Host
Favorableenvironment
Virulent
Pathogen

HISTORY OF PLANTHISTORY OF PLANT
PATHOLOGYPATHOLOGY
Tribes settled and began farmingTribes settled and began farming
In wet or dry years, small crops led toIn wet or dry years, small crops led to
faminefamine
Plant diseases are mentioned in the BiblePlant diseases are mentioned in the Bible
(c750B.C.)(c750B.C.)

Sin was blamed for plant diseasesSin was blamed for plant diseases
The Greek philosopher Theophrastus (cThe Greek philosopher Theophrastus (c
300B.C.)was the first to study and write300B.C.)was the first to study and write
about plant diseaseabout plant disease

History of Plant PathologyHistory of Plant Pathology
Nomadic tribes had to find enoughNomadic tribes had to find enough
healthy foodhealthy food
Homer (c.1000 B.C.) mentioned theHomer (c.1000 B.C.) mentioned the
therapeutic properties of sulfur on planttherapeutic properties of sulfur on plant
diseasedisease
Democritus (c. 470 B.C.) mentioned theDemocritus (c. 470 B.C.) mentioned the
control of blight by sprinkling olive groundscontrol of blight by sprinkling olive grounds
on plantson plants
Most control was festivals and sacrificesMost control was festivals and sacrifices

Magnus A.D. 1200, Germany, proposedMagnus A.D. 1200, Germany, proposed
that mistletoe was a parasitic plant but nothat mistletoe was a parasitic plant but no
one followed up on this.one followed up on this.
French farmers (1600’s) and ConnecticutFrench farmers (1600’s) and Connecticut
farmers (1700’s) noticed that wheat rustfarmers (1700’s) noticed that wheat rust
was worse near barberry bushes.was worse near barberry bushes.
(Alternate hosts)(Alternate hosts)
Around 1667, Hooke (England) observedAround 1667, Hooke (England) observed
the spores with a microscope.the spores with a microscope.

In Italy, Micheli (1729) described theIn Italy, Micheli (1729) described the
structures of fungi and noted that when hestructures of fungi and noted that when he
put the structure on fresh cut melon, theyput the structure on fresh cut melon, they
reproduced the same. He proposed thatreproduced the same. He proposed that
fungi arose from their own spores but nofungi arose from their own spores but no
one believed him.one believed him.

In 1775 Tillet, in France showed that;In 1775 Tillet, in France showed that;
Wheat smut increased with the addition ofWheat smut increased with the addition of
spores to the seedsspores to the seeds
The smut was reduced in seeds treatedThe smut was reduced in seeds treated
with copper sulfatewith copper sulfate
He thought it was a poison rather than aHe thought it was a poison rather than a
microorganismmicroorganism

Provost, 1807 repeated Tillet’s work andProvost, 1807 repeated Tillet’s work and
determined it was the spores that causeddetermined it was the spores that caused
the fungus but the Science Academythe fungus but the Science Academy
would not believe himwould not believe him
The thought they were the result ratherThe thought they were the result rather
than the causethan the cause

Nematodes were first associated withNematodes were first associated with
disease by Needham in 1743disease by Needham in 1743
In 1855 the second nematode wasIn 1855 the second nematode was
observed in cucumber root gallsobserved in cucumber root galls
Several more were discovered in the nextSeveral more were discovered in the next
4 years4 years

In 1876 Pasteur and Koch in France showedIn 1876 Pasteur and Koch in France showed
that anthrax was caused by a bacteriumthat anthrax was caused by a bacterium
In 1878 Burill showed that fire blight was causedIn 1878 Burill showed that fire blight was caused
by bacteriumby bacterium
Acceptance was slowAcceptance was slow
In 1890’s Smith showed crown gall to be causedIn 1890’s Smith showed crown gall to be caused
by bacteriumby bacterium
In 1980 the process of crown gall was finallyIn 1980 the process of crown gall was finally
explained, excessive hormone produce growthexplained, excessive hormone produce growth

VirusesViruses
In1886 Mayer reproduced tobacco mosaicIn1886 Mayer reproduced tobacco mosaic
by injecting juice from a diseased plantby injecting juice from a diseased plant
into a healthy one, he thought it was ainto a healthy one, he thought it was a
bacteriabacteria
In 1892 Ivanowski showed that it was notIn 1892 Ivanowski showed that it was not
a bacteria because it could go through aa bacteria because it could go through a
bacteria sievebacteria sieve

In 1898 Beijerinck concluded that theIn 1898 Beijerinck concluded that the
mosaic was caused by a living fluid whichmosaic was caused by a living fluid which
he called a virushe called a virus
In 1935 Stanley separated the virus asIn 1935 Stanley separated the virus as
sediment in a flasksediment in a flask
The first virus was seen with an electronThe first virus was seen with an electron
microscope in 1939 by Kauschemicroscope in 1939 by Kausche
In 1956, Gierrer and schramm removedIn 1956, Gierrer and schramm removed
protein from the virus and showed RNAprotein from the virus and showed RNA

In 1971 Diener discovered that potatoIn 1971 Diener discovered that potato
spindle tuber disease was a naked singlespindle tuber disease was a naked single
strand circular molecule of infectious RNAstrand circular molecule of infectious RNA
which he called a viroidwhich he called a viroid
An even smaller infectious agent wasAn even smaller infectious agent was
discovered by Prusiner in 1982 which hediscovered by Prusiner in 1982 which he
called a prioncalled a prion
Three human diseases are caused byThree human diseases are caused by
prions, non so far discovered in plantsprions, non so far discovered in plants

Protozoa were observed in EuphorbiaceaeProtozoa were observed in Euphorbiaceae
by Lafont in 1909by Lafont in 1909
1931 Stahel found flagellates in coffee1931 Stahel found flagellates in coffee
treestrees
1963 Vermeulen found evidence of1963 Vermeulen found evidence of
pathogenicity of flagellates in coffee treespathogenicity of flagellates in coffee trees
and coconutand coconut

Mollicutes were discovered in 1967Mollicutes were discovered in 1967
Doi and assoc observed wall-lessDoi and assoc observed wall-less
mycoplasmic bodies infecting plantmycoplasmic bodies infecting plant
exhibiting witches broomexhibiting witches broom

There are many severe diseases for whichThere are many severe diseases for which
no cause has been foundno cause has been found
Forest declineForest decline
Citrus blightCitrus blight
Spear rot of oil palmSpear rot of oil palm
Mango malformationMango malformation
All have unknown causesAll have unknown causes

the experimental phasethe experimental phase
The importance of plant pathology wasThe importance of plant pathology was
realized and added to the USDA offices inrealized and added to the USDA offices in
the late 1800’sthe late 1800’s
As knowledge accumulated,As knowledge accumulated,
experimentation grew rapidly on ways toexperimentation grew rapidly on ways to
control or avoid plant diseasecontrol or avoid plant disease

the etiological phasethe etiological phase
Involved observation and experiments toInvolved observation and experiments to
prove the causes of plant diseaseprove the causes of plant disease
This developed techniques for pureThis developed techniques for pure
cultures to satisfy Koch’s postulatescultures to satisfy Koch’s postulates
This phases depended on theThis phases depended on the
development of instrumentation anddevelopment of instrumentation and
methodologymethodology

The search for disease controlThe search for disease control
Even though the early people madeEven though the early people made
sacrifices to the gods , they did choosesacrifices to the gods , they did choose
plants that were more resistant to diseaseplants that were more resistant to disease
Recommendations for disease controlRecommendations for disease control
have been found as early as 1000B.C.have been found as early as 1000B.C.
Homer, Democritus 470 B.C., andHomer, Democritus 470 B.C., and
Theophrastus 300 B.C.Theophrastus 300 B.C.
The 1600’s show the first reports ofThe 1600’s show the first reports of
resistant varietiesresistant varieties

There were a lot of worthless curesThere were a lot of worthless cures
recommended but a few actually workedrecommended but a few actually worked
such as sulfursuch as sulfur
Seed saved from a ship wreckSeed saved from a ship wreck
(1600’s)had less smut disease than other(1600’s)had less smut disease than other
plants so they started a seed pre-treat withplants so they started a seed pre-treat with
brinebrine
Later this was changed to copper sulfateLater this was changed to copper sulfate
This is still used todayThis is still used today

In the 1800’s lime sulfur was discovered.In the 1800’s lime sulfur was discovered.
The story is a grape farmer made theThe story is a grape farmer made the
mixture to look like bird drops which hemixture to look like bird drops which he
sprayed on his grapes so people walkingsprayed on his grapes so people walking
by the edge of the field would not eatby the edge of the field would not eat
them.them.
He soon noticed the plants that wereHe soon noticed the plants that were
sprayed would not get diseased so hesprayed would not get diseased so he
sprayed everythingsprayed everything

In 1913 organic mercury compounds wereIn 1913 organic mercury compounds were
developed as seed treatments untildeveloped as seed treatments until
mercury was banned in the 1960’smercury was banned in the 1960’s
1934 a series of fungicides were1934 a series of fungicides were
developed; ferbam, zineb, manebdeveloped; ferbam, zineb, maneb
1965 the first systemic, carboxin was1965 the first systemic, carboxin was
discovereddiscovered
Antibiotics were discovered in 1950 & ‘67Antibiotics were discovered in 1950 & ‘67

In 1954 resistant bacteria strains wereIn 1954 resistant bacteria strains were
discovereddiscovered
1963 resistant fungi were discovered1963 resistant fungi were discovered
1970’s new races of fungal pathogens1970’s new races of fungal pathogens
appearedappeared

Public concern developed in the 1950’sPublic concern developed in the 1950’s
Some pesticides such as DDT were foundSome pesticides such as DDT were found
to be harmful to animals, especially birdsto be harmful to animals, especially birds
It did not break down into harmlessIt did not break down into harmless
materials as did most other pesticidesmaterials as did most other pesticides
It and many others have since beenIt and many others have since been
bannedbanned
A book, The Silent Spring by RachelA book, The Silent Spring by Rachel
Carson raised public awarenessCarson raised public awareness

By the 1960’s all mercury was bannedBy the 1960’s all mercury was banned
DDT and chlorinated hydrocarbonsDDT and chlorinated hydrocarbons
Since 1980’s 80% of previous materialsSince 1980’s 80% of previous materials
have been bannedhave been banned
Damages, research, supply have raisedDamages, research, supply have raised
costscosts

Alternative controlsAlternative controls
Cultural practicesCultural practices

Clean up debrisClean up debris

Use certified seedUse certified seed

Remove infected plant partsRemove infected plant parts

Rotate cropsRotate crops

Destroy weedsDestroy weeds

Irrigate, etcIrrigate, etc

I.P.M.I.P.M.

Alternative controlsAlternative controls
1928 Fleming reported that certain soil1928 Fleming reported that certain soil
borne fungi (Penicillium) inhibited theborne fungi (Penicillium) inhibited the
growth of other fungi and bacteriagrowth of other fungi and bacteria
1930’s it was found if you inoculated a1930’s it was found if you inoculated a
plant with a mild form of virus, it wouldplant with a mild form of virus, it would
protect the plant from the severe strainprotect the plant from the severe strain

1972 inoculation with non pathogenic1972 inoculation with non pathogenic
forms of bacteria and fungi prevent theforms of bacteria and fungi prevent the
infection by pathogenic formsinfection by pathogenic forms
1980’s genetic engineering replaced the1980’s genetic engineering replaced the
former methodformer method
A new method is the use ofA new method is the use of
microorganisms or chemicals to formmicroorganisms or chemicals to form
lesions which stimulate natural defenselesions which stimulate natural defense

Interest in the Mechanisms byInterest in the Mechanisms by
Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
Once it was realized the fungi etc causedOnce it was realized the fungi etc caused
the disease instead of the result, thethe disease instead of the result, the
mechanisms were studiedmechanisms were studied
1886 deBary noticed that host cells of1886 deBary noticed that host cells of
SclerotiniaSclerotinia died in advance of thedied in advance of the
pathogenpathogen
This was the discovery of toxins andThis was the discovery of toxins and
enzymes produced by the pathogenenzymes produced by the pathogen

1905 cytolytic enzymes were reported by1905 cytolytic enzymes were reported by
L.R. JonesL.R. Jones
1925 it was suggested that Pseudomonas1925 it was suggested that Pseudomonas
tabaci produced a toxin which causedtabaci produced a toxin which caused
wildfire disease of tobaccowildfire disease of tobacco
1934 it was confirmed1934 it was confirmed
It was the first toxin to be isolated 1950’sIt was the first toxin to be isolated 1950’s

Many toxins and enzymes have sinceMany toxins and enzymes have since
been foundbeen found
There have been many studies about theThere have been many studies about the
mechanisms by which the toxins ormechanisms by which the toxins or
enzymes affect plants and,enzymes affect plants and,
Many studies about the defenseMany studies about the defense
mechanismsmechanisms

1939 IAA was discovered, a growth1939 IAA was discovered, a growth
regulator produced by a fungusregulator produced by a fungus GibberellaGibberella
It is now used in plant propagationIt is now used in plant propagation
1970’s-80’s Agrobacterium tumefaciens1970’s-80’s Agrobacterium tumefaciens
induces crown gall which does a naturalinduces crown gall which does a natural
DNA transplantDNA transplant
It is now used in research and theIt is now used in research and the
production of pharmaceuticalsproduction of pharmaceuticals

Genetic inheritance of ResistanceGenetic inheritance of Resistance
and Pathologyand Pathology
1894 Eriksson discovered different1894 Eriksson discovered different
biological races of Puccinia graminisbiological races of Puccinia graminis
They cannot be differentiated by sight butThey cannot be differentiated by sight but
by their hostsby their hosts
1905 Biffen reported inherited resistance1905 Biffen reported inherited resistance
1909 Orton distinguished between1909 Orton distinguished between
disease escape, endurance, anddisease escape, endurance, and
resistanceresistance

1911 Barrus showed genetic variability1911 Barrus showed genetic variability
within a pathogen specieswithin a pathogen species
1914 Stakmen et al explain resistance and1914 Stakmen et al explain resistance and
susceptibility of the same species insusceptibility of the same species in
different geographical areasdifferent geographical areas
1946 Flor showed that for each gene in1946 Flor showed that for each gene in
the host for resistance there was a gene inthe host for resistance there was a gene in
the pathogen for virulence (gene-for-gene)the pathogen for virulence (gene-for-gene)

1963 Vanderplank described vertical1963 Vanderplank described vertical
resistanceresistance

Few genes, strong but only effect against aFew genes, strong but only effect against a
few racesfew races
Horizontal resistance, weaker but effectiveHorizontal resistance, weaker but effective
against all racesagainst all races

1946 Gaumann proposed hypersensitivity1946 Gaumann proposed hypersensitivity
whereas and area around the site dieswhereas and area around the site dies
and protects the rest of the plantand protects the rest of the plant
1960’s anti microbial substances was1960’s anti microbial substances was
proposed to existproposed to exist

Epidemiology of Plant DiseaseEpidemiology of Plant Disease
Comes of AgeComes of Age
1944 Mills developed a table showing rain1944 Mills developed a table showing rain
and temperature and hoe it affected theand temperature and hoe it affected the
development of apple scabdevelopment of apple scab
1963 Vanderplank wrote Plant Diseases:1963 Vanderplank wrote Plant Diseases:
Epidemics and Control, establishing andEpidemics and Control, establishing and
important field of studyimportant field of study
It is now possible to predict epidemics byIt is now possible to predict epidemics by
keeping recordskeeping records

Epidemiology of Plant DiseaseEpidemiology of Plant Disease
Comes of AgeComes of Age
1969 first computer simulation for early1969 first computer simulation for early
blight of tomato and potatoblight of tomato and potato
Since 1970’s many disease modeling andSince 1970’s many disease modeling and
computer simulations have beencomputer simulations have been
developed for many diseasesdeveloped for many diseases

Molecular Plant PathologyMolecular Plant Pathology
Since 1980’s most functions of genesSince 1980’s most functions of genes
have been mapped and gene transfershave been mapped and gene transfers
have been made to provide resistancehave been made to provide resistance
Early beginnings from 1956 when RNA ofEarly beginnings from 1956 when RNA of
tobacco mosaic virus was shown to betobacco mosaic virus was shown to be
responsible for plant cell infectionresponsible for plant cell infection
1960’s study showed full genetic code for1960’s study showed full genetic code for
a certain amino acida certain amino acid

It was shown that two genes could beIt was shown that two genes could be
removed and replaced and expressed byremoved and replaced and expressed by
the plant cellsthe plant cells
Whole plants could be produced from aWhole plants could be produced from a
single cellsingle cell
This is called tissue culture or propagationThis is called tissue culture or propagation

Foreign DNA can be moved to anotherForeign DNA can be moved to another
plant by using a virus or bacteria as aplant by using a virus or bacteria as a
vectorvector
Since 1980’s segments of DNA have beenSince 1980’s segments of DNA have been
marked with radioactive isotopes andmarked with radioactive isotopes and
trackedtracked
We now have many geneticallyWe now have many genetically
engineered plants such as corn andengineered plants such as corn and
soybeanssoybeans

Development of Plant PathologyDevelopment of Plant Pathology
WorldwideWorldwide
Origins in late 1800’sOrigins in late 1800’s
1891Netherlands Society of Plant1891Netherlands Society of Plant
PathologyPathology
1895 Netherlands Journal of Plant1895 Netherlands Journal of Plant
PathologyPathology
1911 International journal named1911 International journal named
PhytopathologyPhytopathology

WorldwideWorldwide
1916 Phytological Society of Japan1916 Phytological Society of Japan
Began publishing 1918Began publishing 1918
Canada 1930Canada 1930
India 1947India 1947

WorldwideWorldwide
1968 International Society of Plant1968 International Society of Plant
Pathology was foundedPathology was founded
Most parts of the world have plantMost parts of the world have plant
pathologists but a few parts have nonepathologists but a few parts have none
and do not practice controls so losses areand do not practice controls so losses are
greatgreat
1940’s Rockefeller foundation started to1940’s Rockefeller foundation started to
help Mexican governmenthelp Mexican government

WorldwideWorldwide
With great success in the program manyWith great success in the program many
were soon to followwere soon to follow
It was impossible to have suchIt was impossible to have such
foundations in every country sofoundations in every country so
international centers were formedinternational centers were formed

WorldwideWorldwide
International Rice Institute, 1960International Rice Institute, 1960
PhilippinesPhilippines
International Maize and WheatInternational Maize and Wheat
Improvement Center, 1966 MexicoImprovement Center, 1966 Mexico
International Institute of TropicalInternational Institute of Tropical
Agriculture, 1968 NigeriaAgriculture, 1968 Nigeria
International Center of TropicalInternational Center of Tropical
Agriculture, 1969 ColumbiaAgriculture, 1969 Columbia

WorldwideWorldwide
More foundations were needed so aMore foundations were needed so a
consortium of donors was set up with theconsortium of donors was set up with the
World Bank…Consultative Group onWorld Bank…Consultative Group on
International Agriculture ResearchInternational Agriculture Research
Numerous centers were established inNumerous centers were established in
many countriesmany countries
Tropical countries are in special needTropical countries are in special need
because the weather promotes pathogensbecause the weather promotes pathogens

Trends in Teaching and Training inTrends in Teaching and Training in
Plant PathologyPlant Pathology
First course in Plant Pathology was offered atFirst course in Plant Pathology was offered at
Harvard by M.A. Farlow in 1875Harvard by M.A. Farlow in 1875
Textbooks became commonTextbooks became common
Duggar 1906Duggar 1906
Stevans and Hall 1921Stevans and Hall 1921
Heald 1926 & ‘43Heald 1926 & ‘43
Walker 1950Walker 1950
Many specialized books appearedMany specialized books appeared
B.S., M.S., and Ph.D. are available in Plant PathB.S., M.S., and Ph.D. are available in Plant Path

Education and InformationEducation and Information
Technology in Plant PathologyTechnology in Plant Pathology
Many advances have been made inMany advances have been made in
developing, collecting, organizing anddeveloping, collecting, organizing and
transmitting information by researchers,transmitting information by researchers,
teachers etc.teachers etc.
Many data bases have been establishedMany data bases have been established

Plant Disease ClinicsPlant Disease Clinics
Most states have plant disease clinicsMost states have plant disease clinics
operated by plant pathology departmentsoperated by plant pathology departments
and county extension agentsand county extension agents
Since 1970 every state has at least oneSince 1970 every state has at least one
plant disease clinicplant disease clinic
Most are run by M.S. or Ph.D.’sMost are run by M.S. or Ph.D.’s
Most are run by the state department ofMost are run by the state department of
agricultureagriculture

Plant Pathology: The PracticePlant Pathology: The Practice
Most discoveries were and are made byMost discoveries were and are made by
graduate students working on advancegraduate students working on advance
degreesdegrees
The actual practice of plant pathology isThe actual practice of plant pathology is
carried out at a lower level by technicianscarried out at a lower level by technicians
etc. who use the knowledge andetc. who use the knowledge and
techniques of the researcherstechniques of the researchers
The knowledge etc. is transferred throughThe knowledge etc. is transferred through
the county extension agentsthe county extension agents

Most growers receive limited informationMost growers receive limited information
In the last 20 years, pesticide licensingIn the last 20 years, pesticide licensing
has increased the professional level ofhas increased the professional level of
the landscaperthe landscaper
The author of your textbook predicts thereThe author of your textbook predicts there
will be plant doctors on the same level aswill be plant doctors on the same level as
medical doctors.medical doctors.
We have plant doctors now but areWe have plant doctors now but are
basically Ph.D’sbasically Ph.D’s

In the 1960’s-70’s licensing beganIn the 1960’s-70’s licensing began
Many horticulture/landscape associationsMany horticulture/landscape associations
have established certification programshave established certification programs
There is an American Registry of PlantThere is an American Registry of Plant
Pathologists governed by a board ofPathologists governed by a board of
directorsdirectors

To be a certified plant pathologist youTo be a certified plant pathologist you
must have:must have:
B.S. + 5 years professional experienceB.S. + 5 years professional experience
M.S. + 3 years of professional experienceM.S. + 3 years of professional experience
Ph.D. + 1 year of professional experiencePh.D. + 1 year of professional experience
Or complete a recommended course ofOr complete a recommended course of
studystudy

Kinds and amounts of lossesKinds and amounts of losses
Plant disease is important because of thePlant disease is important because of the
losses of food, fiber and other productslosses of food, fiber and other products
Plant loss affects the economyPlant loss affects the economy
People may starve to deathPeople may starve to death
Damage parks, recreational areas andDamage parks, recreational areas and
buildingbuilding
Billions of pounds of pesticides areBillions of pounds of pesticides are
produced and appliedproduced and applied

Plant diseases may limit the kinds ofPlant diseases may limit the kinds of
plants and industry in an areaplants and industry in an area
Chestnut eliminated by blightChestnut eliminated by blight
Elm eliminated by Dutch elm diseaseElm eliminated by Dutch elm disease
White birch only does well in the northWhite birch only does well in the north
European grape cannot be grown inEuropean grape cannot be grown in
southern U.Ssouthern U.S
Plant disease has created whole newPlant disease has created whole new
industry of pesticides and other businessindustry of pesticides and other business

Some plant disease makes the plantSome plant disease makes the plant
poisonous to humans and animals suchpoisonous to humans and animals such
as ergot of rye and wheatas ergot of rye and wheat
Several fungi will make hay poisonousSeveral fungi will make hay poisonous
May contain nematodes which carry virusMay contain nematodes which carry virus
Plant disease causes great financial lossPlant disease causes great financial loss
from a few % to total cropfrom a few % to total crop
The cost of disease control must be lessThe cost of disease control must be less
than cost of crop lossthan cost of crop loss

Pathology introduction

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Pathology introduction