PLANT PATHOLOGYPLANT PATHOLOGYINTRODUCTIONINTRODUCTION
By Muhammad AsifBy Muhammad Asif
INTRODUCTIONINTRODUCTION
Plants make up the majority of earths Plants make up the majority of earths living environmentliving environment
Plants are the only organisms that convert Plants are the only organisms that convert the suns energy to foodthe suns energy to food
All animals including humans depend on All 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
INTRODUCTIONINTRODUCTION
Disease causing organisms include;Disease causing organisms include;
VirusesViruses
BacteriaBacteria
FungiFungi
ProtozoaProtozoa
NematodesNematodes
Or unfavorable environmental conditionsOr unfavorable environmental conditions
INTRODUCTIONINTRODUCTION
Plant pathology is the study of Plant pathology is the study of microorganisms and environmental factors microorganisms and environmental factors that cause plant diseasethat cause plant diseaseThe way they workThe way they workThe way they are avoided or controlledThe way they are avoided or controlledThe cost of control must be less than the The cost of control must be less than the profitprofit
Environment friendly materials must be Environment friendly materials must be usedused
INTRODUCTIONINTRODUCTION
A plant is considered healthy if it functions A 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 by When a plant function is interfered with by a microorganism or environmental factor a 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 of Some 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 famine The Romans were so aware of famine they created a special rust god, Robigo they created a special rust god, Robigo who was responsible to protect people who was responsible to protect people from faminefrom famine
These beliefs lasted about 2000 yearsThese beliefs lasted about 2000 years
The compound microscope was invented The compound microscope was invented in the 1600’sin the 1600’s
CLASSIFICATION OF CLASSIFICATION 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 high temperatureDiseases caused by low or high temperature
Diseases caused by lack or excess soil HDiseases caused by lack or excess soil H22OO
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 or Diseases caused by soil acidity or alkalinityalkalinity
Diseases caused by toxicity of pesticidesDiseases caused by toxicity of pesticides
Diseases caused by improper cultural Diseases caused by improper cultural practicespractices
The Birth of Plant PathologyThe Birth of Plant Pathology
The fungus found on potatoes was first The fungus found on potatoes was first described by Dr. C Montagne, a French described by Dr. C Montagne, a French doctor with Napoleon’s armydoctor with Napoleon’s armyHe shared his observation with Rev. M. J. He shared his observation with Rev. M. J. Berkely who thought it might be connected Berkely who thought it might be connected with the diseasewith the diseaseDr. John Lindley, a rival did not believe Dr. John Lindley, a rival did not believe there was a connectionthere was a connection
The Birth of Plant PathologyThe Birth of Plant Pathology
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 an Sir Robert Peel used the blight as an excuse to repeal the protectionist trade excuse to repeal the protectionist trade laws to import corn from America to feed laws to import corn from America to feed the starving Irish. It was called Peel’s the starving Irish. It was called Peel’s Brimestone” because the recipients were Brimestone” because the recipients were considered ungratefulconsidered ungrateful
The Birth of Plant PathologyThe Birth of Plant Pathology
During a 15 year period 1 million Irish died of During a 15 year period 1 million Irish died of disease and starvation and another 1.5 million disease 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 the The scientist of the time were unable to save the crops but there came an understanding of plant crops but there came an understanding of plant diseasedisease
Anton deBary, a German Botanist performed Anton deBary, a German Botanist performed experiments that proved the role of fungus in the experiments that proved the role of fungus in the blightblight
The Birth of Plant PathologyThe Birth of Plant Pathology
For 200 years people thought the disease For 200 years people thought the disease causing organisms were the result , not the causing organisms were the result , not the causecause
The theory of spontaneous generation was The theory of spontaneous generation was abandoned for the germ theory in 1863abandoned for the germ theory in 1863
It was originally named It was originally named Botrytis infestansBotrytis infestans by by Montagne but was changed to Montagne but was changed to Phytophthora Phytophthora infestansinfestans by deBary because he realized they by deBary because he realized they were not relatedwere not related
The Birth of Plant PathologyThe Birth of Plant Pathology
Phyto= plantPhyto= plant
Phthora =destroyerPhthora =destroyer
Phytophthora= plant destroyerPhytophthora= plant destroyer
Infestans=devastating infestationInfestans=devastating infestation
Usual microorganisms do not have Usual microorganisms do not have common names since only scientist talk common names since only scientist talk about themabout them
Proof of pathogenicityProof of pathogenicityKoch’s postulatesKoch’s postulates
The symptoms and any evidence of the The symptoms and any evidence of the pathogen in the diseases host are carefully pathogen in the diseases host are carefully describeddescribed
The suspected pathogen is isolated from the The 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 same The pathogen is isolated and must be the same as originalas original
When all four steps are complete= proofWhen all four steps are complete= proof
The Birth of Plant PathologyThe Birth of Plant Pathology
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 crops Copper was then known to protect crops but it was needed to make bullets for the but 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 of The potato was from the highlands of South America’s, Lake TiticacaSouth America’s, Lake Titicaca
It was discovered by the Spanish It 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 about The first potatoes reached Europe about 15701570
The Birth of Plant PathologyThe Birth of Plant Pathology
New cultivars were developed New 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 attack The 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
Favo
rabl
e env
ironm
ent
Virulent
Pathogen
HISTORY OF PLANT HISTORY OF PLANT PATHOLOGYPATHOLOGY
Tribes settled and began farmingTribes settled and began farming
In wet or dry years, small crops led to In wet or dry years, small crops led to faminefamine
Plant diseases are mentioned in the Bible Plant 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 (c The Greek philosopher Theophrastus (c 300B.C.)was the first to study and write 300B.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 enough Nomadic tribes had to find enough healthy foodhealthy food
Homer (c.1000 B.C.) mentioned the Homer (c.1000 B.C.) mentioned the therapeutic properties of sulfur on plant therapeutic properties of sulfur on plant diseasediseaseDemocritus (c. 470 B.C.) mentioned the Democritus (c. 470 B.C.) mentioned the control of blight by sprinkling olive grounds control of blight by sprinkling olive grounds on plantson plantsMost control was festivals and sacrificesMost control was festivals and sacrifices
History of Plant PathologyHistory of Plant Pathology
Magnus A.D. 1200, Germany, proposed Magnus A.D. 1200, Germany, proposed that mistletoe was a parasitic plant but no that mistletoe was a parasitic plant but no one followed up on this.one followed up on this.French farmers (1600’s) and Connecticut French farmers (1600’s) and Connecticut farmers (1700’s) noticed that wheat rust farmers (1700’s) noticed that wheat rust was worse near barberry bushes.was worse near barberry bushes.(Alternate hosts)(Alternate hosts)Around 1667, Hooke (England) observed Around 1667, Hooke (England) observed the spores with a microscope.the spores with a microscope.
History of Plant PathologyHistory of Plant Pathology
In Italy, Micheli (1729) described the In Italy, Micheli (1729) described the structures of fungi and noted that when he structures of fungi and noted that when he put the structure on fresh cut melon, they put the structure on fresh cut melon, they reproduced the same. He proposed that reproduced the same. He proposed that fungi arose from their own spores but no fungi arose from their own spores but no one believed him.one believed him.
History of Plant PathologyHistory of Plant Pathology
In 1775 Tillet, in France showed that;In 1775 Tillet, in France showed that;
Wheat smut increased with the addition of Wheat smut increased with the addition of spores to the seeds spores to the seeds
The smut was reduced in seeds treated The smut was reduced in seeds treated with copper sulfatewith copper sulfate
He thought it was a poison rather than a He thought it was a poison rather than a microorganismmicroorganism
History of Plant PathologyHistory of Plant Pathology
Provost, 1807 repeated Tillet’s work and Provost, 1807 repeated Tillet’s work and determined it was the spores that caused determined it was the spores that caused the fungus but the Science Academy the fungus but the Science Academy would not believe himwould not believe him
The thought they were the result rather The thought they were the result rather than the causethan the cause
History of Plant PathologyHistory of Plant Pathology
Nematodes were first associated with Nematodes were first associated with disease by Needham in 1743disease by Needham in 1743
In 1855 the second nematode was In 1855 the second nematode was observed in cucumber root gallsobserved in cucumber root galls
Several more were discovered in the next Several more were discovered in the next 4 years4 years
History of Plant PathologyHistory of Plant Pathology
In 1876 Pasteur and Koch in France showed In 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 caused In 1878 Burill showed that fire blight was caused by bacteriumby bacterium
Acceptance was slow Acceptance was slow
In 1890’s Smith showed crown gall to be caused In 1890’s Smith showed crown gall to be caused by bacteriumby bacterium
In 1980 the process of crown gall was finally In 1980 the process of crown gall was finally explained, excessive hormone produce growthexplained, excessive hormone produce growth
History of Plant PathologyHistory of Plant Pathology
Viruses Viruses
In1886 Mayer reproduced tobacco mosaic In1886 Mayer reproduced tobacco mosaic by injecting juice from a diseased plant by injecting juice from a diseased plant into a healthy one, he thought it was a into a healthy one, he thought it was a bacteriabacteria
In 1892 Ivanowski showed that it was not In 1892 Ivanowski showed that it was not a bacteria because it could go through a a bacteria because it could go through a bacteria sievebacteria sieve
History of Plant PathologyHistory of Plant Pathology
In 1898 Beijerinck concluded that the In 1898 Beijerinck concluded that the mosaic was caused by a living fluid which mosaic was caused by a living fluid which he called a virushe called a virusIn 1935 Stanley separated the virus as In 1935 Stanley separated the virus as sediment in a flasksediment in a flaskThe first virus was seen with an electron The first virus was seen with an electron microscope in 1939 by Kauschemicroscope in 1939 by KauscheIn 1956, Gierrer and schramm removed In 1956, Gierrer and schramm removed protein from the virus and showed RNAprotein from the virus and showed RNA
History of Plant PathologyHistory of Plant Pathology
In 1971 Diener discovered that potato In 1971 Diener discovered that potato spindle tuber disease was a naked single spindle tuber disease was a naked single strand circular molecule of infectious RNA strand circular molecule of infectious RNA which he called a viroidwhich he called a viroidAn even smaller infectious agent was An even smaller infectious agent was discovered by Prusiner in 1982 which he discovered by Prusiner in 1982 which he called a prioncalled a prionThree human diseases are caused by Three human diseases are caused by prions, non so far discovered in plantsprions, non so far discovered in plants
History of Plant PathologyHistory of Plant Pathology
Protozoa were observed in Euphorbiaceae Protozoa were observed in Euphorbiaceae by Lafont in 1909by Lafont in 1909
1931 Stahel found flagellates in coffee 1931 Stahel found flagellates in coffee treestrees
1963 Vermeulen found evidence of 1963 Vermeulen found evidence of pathogenicity of flagellates in coffee trees pathogenicity of flagellates in coffee trees and coconutand coconut
History of Plant PathologyHistory of Plant Pathology
Mollicutes were discovered in 1967Mollicutes were discovered in 1967
Doi and assoc observed wall-less Doi and assoc observed wall-less mycoplasmic bodies infecting plant mycoplasmic bodies infecting plant exhibiting witches broomexhibiting witches broom
History of Plant PathologyHistory of Plant Pathology
There are many severe diseases for which There 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
History of Plant PathologyHistory of Plant Pathologythe experimental phasethe experimental phase
The importance of plant pathology was The importance of plant pathology was realized and added to the USDA offices in realized 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 to experimentation grew rapidly on ways to control or avoid plant diseasecontrol or avoid plant disease
History of Plant PathologyHistory of Plant Pathologythe etiological phasethe etiological phase
Involved observation and experiments to Involved observation and experiments to prove the causes of plant diseaseprove the causes of plant disease
This developed techniques for pure This developed techniques for pure cultures to satisfy Koch’s postulatescultures to satisfy Koch’s postulates
This phases depended on the This phases depended on the development of instrumentation and development of instrumentation and methodologymethodology
History of Plant PathologyHistory of Plant PathologyThe search for disease controlThe search for disease control
Even though the early people made Even though the early people made sacrifices to the gods , they did choose sacrifices to the gods , they did choose plants that were more resistant to diseaseplants that were more resistant to disease Recommendations for disease control Recommendations for disease control have been found as early as 1000B.C. have been found as early as 1000B.C. Homer, Democritus 470 B.C., and Homer, Democritus 470 B.C., and Theophrastus 300 B.C.Theophrastus 300 B.C.The 1600’s show the first reports of The 1600’s show the first reports of resistant varietiesresistant varieties
History of Plant PathologyHistory of Plant Pathology
There were a lot of worthless cures There were a lot of worthless cures recommended but a few actually worked recommended but a few actually worked such as sulfursuch as sulfur
Seed saved from a ship wreck (1600’s)had Seed saved from a ship wreck (1600’s)had less smut disease than other plants so less smut disease than other plants so they started a seed pre-treat with brinethey started a seed pre-treat with brine
Later this was changed to copper sulfateLater this was changed to copper sulfate
This is still used todayThis is still used today
History of Plant PathologyHistory of Plant Pathology
In the 1800’s lime sulfur was discovered.In the 1800’s lime sulfur was discovered.The story is a grape farmer made the The story is a grape farmer made the mixture to look like bird drops which he mixture to look like bird drops which he sprayed on his grapes so people walking sprayed on his grapes so people walking by the edge of the field would not eat by the edge of the field would not eat them.them.He soon noticed the plants that were He soon noticed the plants that were sprayed would not get diseased so he sprayed would not get diseased so he sprayed everythingsprayed everything
History of Plant PathologyHistory of Plant Pathology
In 1913 organic mercury compounds were In 1913 organic mercury compounds were developed as seed treatments until developed as seed treatments until mercury was banned in the 1960’smercury was banned in the 1960’s
1934 a series of fungicides were 1934 a series of fungicides were developed; ferbam, zineb, manebdeveloped; ferbam, zineb, maneb
1965 the first systemic, carboxin was 1965 the first systemic, carboxin was discovereddiscovered
Antibiotics were discovered in 1950 & ‘67Antibiotics were discovered in 1950 & ‘67
History of Plant PathologyHistory of Plant Pathology
In 1954 resistant bacteria strains were In 1954 resistant bacteria strains were discovereddiscovered
1963 resistant fungi were discovered1963 resistant fungi were discovered
1970’s new races of fungal pathogens 1970’s new races of fungal pathogens appearedappeared
History of Plant PathologyHistory of Plant Pathology
Public concern developed in the 1950’sPublic concern developed in the 1950’sSome pesticides such as DDT were found Some pesticides such as DDT were found to be harmful to animals, especially birdsto be harmful to animals, especially birdsIt did not break down into harmless It did not break down into harmless materials as did most other pesticidesmaterials as did most other pesticidesIt and many others have since been It and many others have since been bannedbannedA book, The Silent Spring by Rachel A book, The Silent Spring by Rachel Carson raised public awarenessCarson raised public awareness
History of Plant PathologyHistory of Plant Pathology
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 materials Since 1980’s 80% of previous materials have been bannedhave been banned
Damages, research, supply have raised Damages, 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 soil 1928 Fleming reported that certain soil borne fungi (Penicillium) inhibited the borne fungi (Penicillium) inhibited the growth of other fungi and bacteriagrowth of other fungi and bacteria
1930’s it was found if you inoculated a 1930’s it was found if you inoculated a plant with a mild form of virus, it would plant 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 pathogenic 1972 inoculation with non pathogenic forms of bacteria and fungi prevent the forms of bacteria and fungi prevent the infection by pathogenic formsinfection by pathogenic forms
1980’s genetic engineering replaced the 1980’s genetic engineering replaced the former methodformer method
A new method is the use of A new method is the use of microorganisms or chemicals to form microorganisms or chemicals to form lesions which stimulate natural defenselesions which stimulate natural defense
Interest in the Mechanisms by Interest in the Mechanisms by Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
Once it was realized the fungi etc caused Once it was realized the fungi etc caused the disease instead of the result, the the disease instead of the result, the mechanisms were studiedmechanisms were studied
1886 deBary noticed that host cells of 1886 deBary noticed that host cells of SclerotiniaSclerotinia died in advance of the died in advance of the pathogenpathogen
This was the discovery of toxins and This was the discovery of toxins and enzymes produced by the pathogenenzymes produced by the pathogen
Interest in the Mechanisms by Interest in the Mechanisms by Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
1905 cytolytic enzymes were reported by 1905 cytolytic enzymes were reported by L.R. JonesL.R. Jones
1925 it was suggested that Pseudomonas 1925 it was suggested that Pseudomonas tabaci produced a toxin which caused tabaci 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
Interest in the Mechanisms by Interest in the Mechanisms by Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
Many toxins and enzymes have since Many toxins and enzymes have since been foundbeen found
There have been many studies about the There have been many studies about the mechanisms by which the toxins or mechanisms by which the toxins or enzymes affect plants and,enzymes affect plants and,
Many studies about the defense Many studies about the defense mechanismsmechanisms
Interest in the Mechanisms by Interest in the Mechanisms by Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
1939 IAA was discovered, a growth 1939 IAA was discovered, a growth regulator produced by a fungus regulator produced by a fungus GibberellaGibberella
It is now used in plant propagationIt is now used in plant propagation
1970’s-80’s Agrobacterium tumefaciens 1970’s-80’s Agrobacterium tumefaciens induces crown gall which does a natural induces crown gall which does a natural DNA transplantDNA transplant
It is now used in research and the It is now used in research and the production of pharmaceuticals production of pharmaceuticals
Genetic inheritance of Resistance Genetic inheritance of Resistance and Pathologyand Pathology
1894 Eriksson discovered different 1894 Eriksson discovered different biological races of Puccinia graminisbiological races of Puccinia graminis
They cannot be differentiated by sight but They cannot be differentiated by sight but by their hostsby their hosts
1905 Biffen reported inherited resistance1905 Biffen reported inherited resistance
1909 Orton distinguished between disease 1909 Orton distinguished between disease escape, endurance, and resistanceescape, endurance, and resistance
Interest in the Mechanisms by Interest in the Mechanisms by Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
1911 Barrus showed genetic variability 1911 Barrus showed genetic variability within a pathogen specieswithin a pathogen species
1914 Stakmen et al explain resistance and 1914 Stakmen et al explain resistance and susceptibility of the same species in susceptibility of the same species in different geographical areasdifferent geographical areas
1946 Flor showed that for each gene in 1946 Flor showed that for each gene in the host for resistance there was a gene in the host for resistance there was a gene in the pathogen for virulence (gene-for-gene)the pathogen for virulence (gene-for-gene)
Interest in the Mechanisms by Interest in the Mechanisms by Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
1963 Vanderplank described vertical 1963 Vanderplank described vertical resistance resistance Few genes, strong but only effect against a Few genes, strong but only effect against a
few racesfew races
Horizontal resistance, weaker but effective Horizontal resistance, weaker but effective against all racesagainst all races
Interest in the Mechanisms by Interest in the Mechanisms by Which Pathogens Cause DiseaseWhich Pathogens Cause Disease
1946 Gaumann proposed hypersensitivity 1946 Gaumann proposed hypersensitivity whereas and area around the site dies and whereas and area around the site dies and protects the rest of the plantprotects the rest of the plant
1960’s anti microbial substances was 1960’s anti microbial substances was proposed to existproposed to exist
Epidemiology of Plant Disease Epidemiology of Plant Disease Comes of AgeComes of Age
1944 Mills developed a table showing rain 1944 Mills developed a table showing rain and temperature and hoe it affected the and 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 and Epidemics and Control, establishing and important field of studyimportant field of study
It is now possible to predict epidemics by It is now possible to predict epidemics by keeping recordskeeping records
Epidemiology of Plant Disease Epidemiology of Plant Disease Comes of AgeComes of Age
1969 first computer simulation for early 1969 first computer simulation for early blight of tomato and potatoblight of tomato and potato
Since 1970’s many disease modeling and Since 1970’s many disease modeling and computer simulations have been computer simulations have been developed for many diseasesdeveloped for many diseases
Molecular Plant PathologyMolecular Plant Pathology
Since 1980’s most functions of genes Since 1980’s most functions of genes have been mapped and gene transfers have been mapped and gene transfers have been made to provide resistancehave been made to provide resistance
Early beginnings from 1956 when RNA of Early beginnings from 1956 when RNA of tobacco mosaic virus was shown to be tobacco mosaic virus was shown to be responsible for plant cell infectionresponsible for plant cell infection
1960’s study showed full genetic code for 1960’s study showed full genetic code for a certain amino acida certain amino acid
Molecular Plant PathologyMolecular Plant Pathology
It was shown that two genes could be It was shown that two genes could be removed and replaced and expressed by removed and replaced and expressed by the plant cellsthe plant cells
Whole plants could be produced from a Whole plants could be produced from a single cellsingle cell
This is called tissue culture or propagationThis is called tissue culture or propagation
Molecular Plant PathologyMolecular Plant Pathology
Foreign DNA can be moved to another Foreign DNA can be moved to another plant by using a virus or bacteria as a plant by using a virus or bacteria as a vectorvectorSince 1980’s segments of DNA have been Since 1980’s segments of DNA have been marked with radioactive isotopes and marked with radioactive isotopes and trackedtrackedWe now have many genetically We now have many genetically engineered plants such as corn and engineered plants such as corn and soybeanssoybeans
Development of Plant Pathology Development of Plant Pathology WorldwideWorldwide
Origins in late 1800’sOrigins in late 1800’s
1891Netherlands Society of Plant 1891Netherlands Society of Plant PathologyPathology
1895 Netherlands Journal of Plant 1895 Netherlands Journal of Plant PathologyPathology
1911 International journal named 1911 International journal named PhytopathologyPhytopathology
Development of Plant Pathology Development of Plant Pathology WorldwideWorldwide
1916 Phytological Society of Japan1916 Phytological Society of Japan
Began publishing 1918Began publishing 1918
Canada 1930Canada 1930
India 1947India 1947
Development of Plant Pathology Development of Plant Pathology WorldwideWorldwide
1968 International Society of Plant 1968 International Society of Plant Pathology was foundedPathology was founded
Most parts of the world have plant Most parts of the world have plant pathologists but a few parts have none pathologists but a few parts have none and do not practice controls so losses are and do not practice controls so losses are greatgreat
1940’s Rockefeller foundation started to 1940’s Rockefeller foundation started to help Mexican government help Mexican government
Development of Plant Pathology Development of Plant Pathology WorldwideWorldwide
With great success in the program many With great success in the program many were soon to followwere soon to follow
It was impossible to have such It was impossible to have such foundations in every country so foundations in every country so international centers were formedinternational centers were formed
Development of Plant Pathology Development of Plant Pathology WorldwideWorldwide
International Rice Institute, 1960 International Rice Institute, 1960 PhilippinesPhilippines
International Maize and Wheat International Maize and Wheat Improvement Center, 1966 MexicoImprovement Center, 1966 Mexico
International Institute of Tropical International Institute of Tropical Agriculture, 1968 NigeriaAgriculture, 1968 Nigeria
International Center of Tropical International Center of Tropical Agriculture, 1969 ColumbiaAgriculture, 1969 Columbia
Development of Plant Pathology Development of Plant Pathology WorldwideWorldwide
More foundations were needed so a More foundations were needed so a consortium of donors was set up with the consortium of donors was set up with the World Bank…Consultative Group on World Bank…Consultative Group on International Agriculture ResearchInternational Agriculture Research
Numerous centers were established in Numerous centers were established in many countriesmany countries
Tropical countries are in special need Tropical countries are in special need because the weather promotes pathogensbecause the weather promotes pathogens
Trends in Teaching and Training in Trends in Teaching and Training in Plant PathologyPlant Pathology
First course in Plant Pathology was offered at First course in Plant Pathology was offered at Harvard by M.A. Farlow in 1875Harvard by M.A. Farlow in 1875Textbooks became common Textbooks became common Duggar 1906Duggar 1906Stevans and Hall 1921Stevans and Hall 1921Heald 1926 & ‘43Heald 1926 & ‘43Walker 1950Walker 1950Many specialized books appearedMany specialized books appearedB.S., M.S., and Ph.D. are available in Plant PathB.S., M.S., and Ph.D. are available in Plant Path
Education and Information Education and Information Technology in Plant PathologyTechnology in Plant Pathology
Many advances have been made in Many advances have been made in developing, collecting, organizing and developing, 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 clinics Most states have plant disease clinics operated by plant pathology departments operated by plant pathology departments and county extension agentsand county extension agents
Since 1970 every state has at least one Since 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 of Most are run by the state department of agricultureagriculture
Plant Pathology: The PracticePlant Pathology: The Practice
Most discoveries were and are made by Most discoveries were and are made by graduate students working on advance graduate students working on advance degreesdegreesThe actual practice of plant pathology is The actual practice of plant pathology is carried out at a lower level by technicians carried out at a lower level by technicians etc. who use the knowledge and etc. who use the knowledge and techniques of the researcherstechniques of the researchersThe knowledge etc. is transferred through The knowledge etc. is transferred through the county extension agentsthe county extension agents
Plant Pathology: The PracticePlant Pathology: The Practice
Most growers receive limited informationMost growers receive limited informationIn the last 20 years, pesticide licensing In the last 20 years, pesticide licensing has increased the professional level of the has increased the professional level of the landscaperlandscaperThe author of your textbook predicts there The author of your textbook predicts there will be plant doctors on the same level as will be plant doctors on the same level as medical doctors. medical doctors. We have plant doctors now but are We have plant doctors now but are basically Ph.D’sbasically Ph.D’s
Plant Pathology: The PracticePlant Pathology: The Practice
In the 1960’s-70’s licensing beganIn the 1960’s-70’s licensing began
Many horticulture/landscape associations Many horticulture/landscape associations have established certification programshave established certification programs
There is an American Registry of Plant There is an American Registry of Plant Pathologists governed by a board of Pathologists governed by a board of directorsdirectors
Plant Pathology: The PracticePlant Pathology: The Practice
To be a certified plant pathologist you To 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 of Or complete a recommended course of studystudy
Kinds and amounts of lossesKinds and amounts of losses
Plant disease is important because of the Plant 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 and Damage parks, recreational areas and buildingbuilding
Billions of pounds of pesticides are Billions of pounds of pesticides are produced and appliedproduced and applied
Plant Pathology: The PracticePlant Pathology: The Practice
Plant diseases may limit the kinds of Plant diseases may limit the kinds of plants and industry in an areaplants and industry in an areaChestnut eliminated by blightChestnut eliminated by blightElm eliminated by Dutch elm diseaseElm eliminated by Dutch elm diseaseWhite birch only does well in the northWhite birch only does well in the northEuropean grape cannot be grown in European grape cannot be grown in southern U.Ssouthern U.SPlant disease has created whole new Plant disease has created whole new industry of pesticides and other businessindustry of pesticides and other business
Plant Pathology: The PracticePlant Pathology: The Practice
Some plant disease makes the plant Some plant disease makes the plant poisonous to humans and animals such as poisonous to humans and animals such as ergot of rye and wheatergot of rye and wheatSeveral fungi will make hay poisonousSeveral fungi will make hay poisonousMay contain nematodes which carry virusMay contain nematodes which carry virusPlant disease causes great financial loss Plant disease causes great financial loss from a few % to total cropfrom a few % to total cropThe cost of disease control must be less The cost of disease control must be less than cost of crop lossthan cost of crop loss
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