Kuliah Fitopat Disease Progress

8/12/2019 Kuliah Fitopat Disease Progress

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Disease Progress

Disease on plants usually starts

out at a low level, a small number

of plants affected and a smallamount of plant tissue affected,

and it becomes of concern to us

only when its incidence andseverity increases with time.


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Disease Progress

When we look at some examples ofplant disease epidemics from thepublished literature, we not only

notice that the incidence or severitystarts near zero and then increasesdramatically, but we alsocan discernsome distinct patterns of

development with time.


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Disease Progress

For example, in Phytophthora blight of

pepper seedlings (Phytophthora

capsici) and Fusarium kernel rot(Fusarium moniliforme) of maize,

disease progress is roughly linear

(allowing for some minor deviationsthat we can consider random error)


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Phytophthora blight of pepper seedlings


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Fusarium kernel rot of maize


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Disease Progress

On the other hand, in bean rust (Uromyces

phaseoli) and grey leaf spot of corn

(Cercospora zeae-maydis), there is a

definite upward curve; that is, diseaseincreases at an increasing rate, a curve we

could call exponential.


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Bean rust


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Grey leafspot of

maize


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Disease Progress

Obviously plant disease cannot continue toincrease forever, and as the level of diseaseapproaches 100%, the disease progress

curve gradually flattens out. For example, inepidemicssuch as the infection of beans bySclerotium rolfsiior the infection of tobaccoby Phytophthora parasiticavar. nicotianae,

disease progress starts out looking linearbut slows down as it approaches amaximum.


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Sclerot ium rol fs i ion beans


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Black shank on tobacco


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Disease Progress

Likewise, the disease progress curves of

Puccinia graminissubsp. graminicolaon

ryegrass and Pyrenophora teresf. sp. teres

on barley appear exponential at first, but astime goes on and the incidence and severity

of disease approach 100%, the rate of

disease progress gradually slows to zero,giving both curves a somewhat sigmoid

shape ("S" shape).


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Black stem rust on ryegrass


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Net blotch on barley


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To be sure, not all examples of

disease progress can be as neatly

categorized as these, but in general

plant disease epidemics tend to be

either roughly linear or exponential in

the early stages, and they tend to

level off as they approach some limit.


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The impact of plant disease and the

losses that it causes are a function of

disease progress. To reduce this

impact, we need not eliminate the

disease, we merely need to keep

disease development below anacceptable level.That means that the

progress of disease and the factors that

influence disease progress must beunderstood in quantitative terms.


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1.what kinds of diseases lead to linear disease

progressand what factors affect the slope of the line

(the rate of disease progress).

2. what kinds of diseases tend to produce

exponential disease progresscurves and how we

can reduce both the starting level of disease andthe

rate of epidemic development.

3. why epidemics sometimes level off and what

imposes limits to their development.

We have to know :


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The Cyclical Nature of Plant

Disease


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The inoculum,

which might

consist of

gains entry into and establishment

within the host tissues through the

process of infection.
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The pathogen develops within the

host and eventually begins to

produce new inoculum, which, in

turn, can be dispersed to new

susceptible sites to initiate new

infections.


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Pathogens that produce only one

cycle of development (one infection

cycle) per crop cycle are called

monocyclic, while pathogens thatproduce more than one infection

cycle per crop cycle are called

polycyclic.


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Generally in temperate climatesthere isonly one crop cycle per year, so the terms

"monocyclic" and "polycyclic" are basedon the number of cycles per year. Intropical or subtropical climates, however,there can be more than one crop cycle

per year, and it is important to rememberthat "monocyclic" and "polycyclic" arebased on a single crop cycle. These sameterms are used to describe the epidemics

as well as the pathogens, so we oftenspeak of a "monocyclic epidemic"or a"polycyclic epidemic".


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Change : often increase -- a dynamic process

Disease : dealing with diseases, not just the

pathogen (or plant/crop)

Host : Organism infected (or potentially

infected) by another organism

Population : a population phenomenon

Time and space : two physical dimensions

of interest.


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Epidemiology:

Study of epidemics.

Science of disease in populations. Ecology of disease.

Study of the spread of diseases, in space andtime,

with the objective to trace factors that areresponsible for, or contribute to, epidemic

occurrence.

The science of populations of pathogens inpopulations of host plants, and the diseases

resulting therefrom under the influence of

the environment and human interferences.


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All plant diseases result from a three-way

interaction between the host, the pathogen

andthe environment.

An epidemic develops if all three of these

factors are favourable to diseasedevelopment.

Therefore, disease can be controlled by

manipulating one or more of these factorsso

that conditions are unsuitable for replication,

survival or infection by the pathogen.


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Since the beginning of agriculture, generations

of farmers have been evolving practices for

combating the various plagues suffered by our

crops. Following our discovery of the causes ofplant diseases in the early nineteenth century,

our growing understanding of the interactions of

pathogen and host has enabled us to develop a

wide array of measures for the control of specific

plant diseases.


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From this accumulated knowledge

base, we can distill some general

principles of plant disease controlthat can help us address the

management of new problems onwhatever crop in any environment.

O h t f i i l fi t


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One such set of principles, first

articulated by H. H. Whetzel in 1929

and modified somewhat by variousauthors over the years, has been

widely adopted and taught to

generations of plant pathologystudents around the world. These

"traditional principles", as they have

come to be known, were outlined by acommittee of the US National

Academy of Sciences, 1968.


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Avoidanceprevent disease by selecting a time of the year or

a site where there is no inoculum or where the environment isnot favorable for infection.

Exclusionprevent the introduction of inoculum.

Eradicationeliminate, destroy, or inactivate the inoculum.

Protectionprevent infection by means of a toxicant or some

other barrier to infection.

Resistanceutilize cultivars that are resistant to or tolerant of

infection.

Therapy

cure plants that are already infected.

Traditional Principles of Plant Disease Control


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While these principles are as valid today asthey were in 1929, in the context of modern

concepts of plant disease management, theyhave some critical shortcomings.

First of all,these principles are stated inabsolute terms (e.g., "exclude", "prevent", and

"eliminate") that imply a goal of zero disease.Plant disease "control" in this sense is notpractical, and in most cases is not evenpossible. Indeed, we need not eliminate a

disease; we merely need to reduce its progressand keep disease development below anacceptable level. Instead of plant diseasecontrol, we need to think in terms of plant

disease management.


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Furthermore, considering that different

diseases differ in their dynamics, they donot indicate the relative effectiveness of

the various tactics for the controlof a

particular disease. They also fail to show

how the different disease control

measures interact in their effects on

disease dynamics. We need some means

of assessing quantitatively the effects ofvarious control measures, singly and in

combination, on the progress of disease.


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Finally, the traditional principles of

plant disease control tend to

emphasize tactics without fitting

them into an adequate overall

strategy.

Does this mean that we should

abandon the traditional principles? Of

course not! We merely have to fit theminto an appropriate overall strategy

based on epidemiological principles.

The Epidemiological Basis of Disease


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The Epidemiological Basis of Disease

ManagementPlant disease epidemics can be classified into two basic types,

monocyclic and polycyclic, depending on the number ofinfection cycles per crop cycle. (See: The Cyclical Nature of

Plant Disease.)


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The early stages of a monocyclic epidemic can be

described quite well by a linear model, while the early

stages of a polycyclic epidemic can be described with an

exponential model. Since we are concerned with keeping

disease levels well below 100%, there is no need to

adjust the models for approaching the upper limit, and

we can use the simple linear and exponential models toplan strategies:

Examining these models we can see that in both there are


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1. Reduce the initial inoculum (Qin the

monocyclic model and xoin the polycyclic

model). (Actually xois the initial incidence of

disease, which is proportional to the initialinoculum.)

2. Reduce the rate of infection (Rin the

monocyclic model and rin the polycyclicmodel)

3. Reduce the duration of the epidemic (the time,

t, at the end of the epidemic)

Examining these models, we can see that in both there are

three ways in which we can reduce xat any point in the

epidemic:


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These can be used as three major

strategiesfor managing plant diseaseepidemics, and we can organize our

plant disease control tacticsunder one

or more of these overall strategies.

Furthermore, by means of the model we

can assess the quantitative impact of

each strategy, not only by itself, but in

its interaction with others.


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It is clear from the above model of a monocyclic

epidemic that Q, R, and t have equal weight intheir effect on x. A reduction in the initial

inoculum or the rate of infection will result in a

reduction in the level of disease by the sameproportion at any time, t, throughout the epidemic.

If tcan be reduced (for example, by shortening the

season), disease will be reduced proportionately.

The monocyclic

model

The polycyclic


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The polycyclic

model If ris very high, the apparent

effect of reducing xois to delaythe epidemic.

If ris very high, xomust be reduced to very

low levels to have a significant effect on theepidemic.

Reducing rhas a relatively greater effect onthe epidemic than reducing x

o.

Reducing xomakes good strategic sense onlyif ris low or if ris also being reduced.


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The Traditional Principles Revisited

To make the conceptual leap from disease

control to disease management, the

traditional principles can be modified by

fitting them as tactics within each of the

three major disease management strategies

and by slightly changing the wording toreflect the quantitative impact of the action

rather than an absolute effect:


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PRINSIP PENGELOLAAN PENYAKIT

TUMBUHAN

Pada prinsipnya, untuk mengelola penyakit tumbuhanada strategidan ada taktikyang dapat digunakan.

Taktik dipakai untuk mencapai tujuan berdasar strategiyang dicanangkan.

Secara umum, ada tiga strategi yang dapat dilakukanuntuk pengendalian penyakit tumbuhan yaitu :

(1) strategi untuk mengurangi inokulum awal,

(2) strategi untuk mengurangi laju infeksi, dan

(3) strategi untuk mengurangi lamanya epidemi.

Sedangkan taktik pada prinsipnya ada enam, yaituavoidan, ekslusi, eradikasi, proteksi, resistensi, danterapi.


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Tactics for the Reduction of Initial Inoculum

Avoidancereduce the level of disease by selecting aseason or a site where the amount of inoculum is loworwhere the environment is unfavorable for infection

Exclusionreduce the amount of initial inoculum introducedfrom outside sources

Eradicationreduce the production of initial inoculum bydestroying or inactivating the sources of initial inoculum(sanitation, removal of reservoirs of inoculum, removal ofalternate hosts, etc.)

Protectionreduce the level of initial infection by means ofa toxicant or other barrier to infection

Resistanceuse cultivars that are resistant to infection,particularly the initial infection

Therapyuse thermotherapy, chemotherapy and/ormeristem culture to produce certified seed or vegetativeplanting stock

Tactics for the Reduction of the Infection


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Tactics for the Reduction of the Infection

Rate

Avoidancereduce the rate of production of inoculum, therate of infection, or the rate of development of the pathogenby selecting a season or a site where the environment isnot favorable

Exclusionreduce the introduction of inoculum fromexternal sources during the course of the epidemic

Eradicationreduce the rate of inoculum production duringthe course of the epidemic by destroying or inactivating thesources of inoculum (roguing)

Protectionreduce the rate of infection by means of atoxicant or some other barrier to infection

Resistanceplant cultivars that can reduce the rate ofinoculum production, the rate of infection, or the rate ofpathogen development

Therapycure the plants that are already infected orreduce their production of inoculum

T ti f th R d ti f th


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Tactics for the Reduction of the

Duration of the Epidemic

Avoidanceplant early maturing cultivars

or plant at a time that favors rapid

maturation of the crop

Exclusiondelay the introduction of

inoculum from external sources by means

of plant quarantine

PENGENDALIAN PENYAKIT TUMBUHAN


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MENGURANGI LAJU INFEKSI

MENGURANGI LAMANYA EPIDEMI

MENGURANGI INOKULUM AWAL

EKSLUSI

AVOIDAN

STRATEGI

Waktu tanam, lahan, lingkungan yg tak cocok untukpatogen

Mengurangi jumlah inokulum awal yang berasal dariluar lahan

Sanitasi, buang sumber inokulum, musnahkan inangantara, dsb.

Aplikasi fungisida, atau buat penghalang infeksi pdtanaman

Kultivar yang tahan terhadap infeksi inokulum awal

Terapi panas, kimia, benih / bag. tan. vegetativ bebaspenyakit

EKSLUSI

TERAPI

ERADIKASI

RESISTEN

PROTEKSI

TAKTIK

AVOIDAN

Laju dikurangi dg waktu tanam, lahan, lingkungan ygtak cocok

Kurangi masuknya inokulum selama terjadinyaepidemi

Tebang, pangkas, musnahkan inokulum saatterjadinya epidemi

Kurangi laju infeksi dengan fungisida ataupenghalang lain

Kultivar yang mengurangi laju in-feksi/perkemb.patogen/inokulum

Sembuhkan tanaman yang telah terinfeksi

EKSLUSI

TERAPI

ERADIKASI

RESISTEN

PROTEKSI

AVOIDAN

Tanaman cepat dewasa agar terhindar dari infeksi

Hambat introduksi inokulum dari luar dengankarantina


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Cara pendekatan pendekatan terhadap tanaman

pendekatan yang ditujukan terhadappenyebab penyakit tertentu

Terintegrasi ke dalamMETODA PENGENDALIAN


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Penghindaran patogen

Pemilihan daerah pertanian.

Pemilihan waktu tanam.

Penggunaan benih yang bebas penyakit.


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Eksklusi patogen

Perawatan bahan tanaman.

Karantina tumbuhan.

Pembasmian serangga vektor.


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Erad ikasi patogen

Pergiliran tanam.

Membuang atau menghancurkan tanaman

atau bagian tanaman yang terserang.

Perlakuan tanah.


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Perl indungan tanaman

Pengendalian serangga pembawa

patogen.

Mengubah keadaan lingkungan.

Mengubah keadaan zat hara.

M b k t


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Mengembangkan tanaman yang

resisten

Resistensi fisiologis

Resistensi mekanis

Resistensi fungsional

Resistensi oleh Khemoterapi

a. Resistensi fisiologis yang biasanya


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g y g y

didasarkan kepada adanya zat di dalam

protoplasma yang menghambat infeksi

patogen dan perkembangannya lebihlanjut di dalam tanaman.

b. Resistensi mekanis yang berhubungan

dengan struktur atau morfologi dari bagian-bagian tanaman tertentu meliputi sifat

karakteristik yang dipunyai oleh tanaman

yang menyulitkan patogen mengadakan

kontak secara langsung dengan bagian

yang akan diinfeksinya seperti adanya

lapisan kutikula atau lapisan gabus yang

tebal.

R i i f i l


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c. Resistensi fungsionalyang

berhubungan dengan waktu penutupan

stomata.d. Resistensi oleh Khemoterapidimana

terdapat kemungkinan mengubah

ketahanan terhadap patogen yangterdapat dalam protoplasma dengan

pemberian senyawa kimiapada

tanaman. Pada umumnya cara tersebutmemperlambat atau mengurangi

timbulnya penyakit.

T i d ib ik k d


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Terapi yang d iberikan kepada

tanaman saki t

Khemoterapi.

Perlakuan panas. Menghilangkan bagian tanaman yang

kena infeksi.


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Metoda pengendalian

1. Regulatory

2. Cultural

3. Biological

4. Physical

5. Chemical


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Regulatory control

Menangkal suatu patogen dari

suatu inang atau dari suatu areageografis tertentu


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Regulatory Control


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Cultural control

Mengusahakan tanaman terhindar dari

kontak dengan patogen, mengusahakan

kondisi lingkungan tidak menguntungkanbagi patogen dan melenyapkan atau

mengurangi jumlah patogen pada suatu

tanaman, lahan atau wilayah


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Biological control

Meningkatkan resistensi inang atau

menciptakan kondisi yang menguntungkan

bagi mikroorganisma antagonistik bagi

patogen


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Physical and chemical control

Melindungi tanaman dari inokulum patogen

yang sudah ada atau akan ada, atau

mengobati suatu infeksi yang sudah/sedang

berlangsung


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MENGURANGI LAJU

INFEKSI

MENGURANGI LAMANYA

EPIDEMI

MENGURANGI

INOKULUM AWAL

PENGENDALIAN PENYAKIT TUMBUHAN

EKSLUSI

AVOIDAN

STRATEGI

EKSLUSI

TERAPI

ERADIKASI

RESISTEN

PROTEKSI

TAKTIK

AVOIDAN

EKSLUSI

TERAPI

ERADIKASI

RESISTEN

PROTEKSI

AVOIDAN


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PENGENDALIAN PENYAKIT

TUMBUHAN SECARA KIMIAWI

pestisida

PERATURAN PEMERINTAH NO


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PERATURAN PEMERINTAH NO.

7 TAHUN 1973

Untuk melindungi keselamatan manusia

dan sumber-sumber kekayaan alam

khususnya kekayaan alam hayati, dansupaya pestisida dapat digunakan efektif,

maka peredaran, penyimpanan dan

penggunaan pestisida diatur dengan

Peraturan Pemerintah No. 7 Tahun 1973.

Dalam peraturan tersebut antara lain

ditentukan bahwa:

tiap pestisida harus didaftarkan kepada Menteri


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p p pPertanian melalui Komisi Pestisida untuk dimintakanizin penggunaannya

hanya pestisida yang penggunaannya terdaftar dan

atau diizinkan oleh Menteri Pertanian boleh disimpan,diedarkan dan digunakan

pestisida yang penggunaannya terdaftar dan ataudiizinkan oleh Menteri Pertanian hanya boleh

disimpan, diedarkan dan digunakan menurutketentuan-ketentuan yang ditetapkan dalam izinpestisida itu

tiap pestisida harus diberi label dalam bahasaIndonesia yang berisi keterangan-keterangan yang

dimaksud dalam surat Keputusan Menteri PertanianNo. 429/ Kpts/Mm/1/1973 dan sesuai denganketentuan-ketentuan yang ditetapkan dalampendaftaran dan izin masing-masing pestisida.

Wh t i f i id ?


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What is a fungicide?

Fungicides are pesticides that specifically killfungi or inhibit fungal development

About 40 different classes of fungicides used for

plant protection

Classes are based on target site andbiochemical mode of action


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M 14 3 11 1 12 19 2 7 4 33multisite aromatic

hydrocarbons

sterol

biosynthesis

inhibitors

QoIs benzimidazoles phenylpyrroles polyoxins dicarboximides carboximides phenylamides phosphonates

protein-proteinbonds

lipidperoxidation

sterol integrationin cell

membranes

mitochondrialrespiration in

complex III

(cyt b)

beta-tubulinassembly in cell

division

os-1histidinekinase in

osmotic

regulationpathways

chitin(cell wall)

synthesis

os-2histidinekinase in

osmotic

regulationpathways

mitochondrialrespiration in

complex II

(succinatedehydrogenase)

RNA polymerase unknown

Mzmancozeb

PcPCNB

Fefenarimol

Azazoxystrobin

Tmthiophanate-

methyl

Flfludioxonil

Pdpolyoxin-D

Ipiprodione

Ftflutolanil

Mfmefenoxam

Fafosetyl-Al

Chchlorothalonil

Mymyclobutanil

Flfluoxastrobin

Vivinclozlin

Boboscalid

Cucopper

hydroxide

Prpropiconazole

Pypyraclostrobin

Tdtriadimefon

Tftrifloxystrobin

Trtriticonazole

CCllaassssiiffiiccaattiioonnTTaabblleeooffTTuurrffggrraassssFFuunnggiicciiddeess

bbaasseeddoonnmmooddeeooffaaccttiioonnmmoorreeiinnffooaattwwwwww..ffrraacc..iinnffoo

aanndd

wwwwww..ttuurrffppaatthhoollooggyy..uuccrr..eedduu

Multi-site Site-specific

Systemicity


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Systemicity

Do not penetrate into plant

Redistribute on plant

surfaces Multi-site inhibitors

Kills spores/inhibitsgermination

Protectant only

Broad spectrum

Penetrate into plant

Redistribute on & within

plants Single-site inhibitors

Inhibits spore germinationand or mycelial growth

Protectant and curative

Selective

Non-systemic Systemic

Non systemics


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Non-systemics

Mimimal redistribution fromthe point of deposition

Works by contact with the

fungus

Adequate coverage isessential

On the cuticle

Redistributed washed off by

water EBDCs, Chlorothalanil, etc.


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Systemics

Local Systemic

Local redistribution

from the point of

deposition On the cuticle

Through the leaf

(translaminar)

Extent is variable


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Systemics

Limited systemic

(acropetal penetrant)

Good movement from

the point of application Through tissues

Inside the vasculature

Bulk movement

DMIs, Phenylamides


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Systemics

True Systemics(Basipetal penetrant)

Only one fungcide

Fosetyl-Al Moves through plant

Down into roots

Good against soil-

borne oomycetes

Single Site v Multi-site


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Single Site v. Multi site

Systemic v. non-Systemic

Protectant only

Can wash off

Shorter application

intervals

Broad spectrum

Low Risk of Resistance

Protectant and curative

Less prone to washing off

Longer application

intervals

Selective

High Risk of Resistance

Non-systemic/Multi-Site Systemic/Single Site

Pola Laku Kimiawi pada


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Biological mode of action

Aksi Fungisida dapat diekspresikan melalui

salah satu dari dua cara ekspresi fisik

Penghambatan perkecambahan

spora.

Penghambatan pertmbuhan jamur.

Pola Laku Kimiawi pada

Pengendalian Penyakit Tanaman


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Physiological mode of action

Apa yang terjadi pada tingkatan

seluler shg dapat menyebabkanpengaruh visibel pada

perkecambahan spora dan

pertumbuhan jamur?


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Mengapa perlu mengenali pola laku

fungisida secara fisiologis?

For resistance management and preservation of fungicide

effectiveness.

Untreated

Treated


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The physiological mode of

action Fungicides are metabolic inhibitors andtheir modes of action can be classified into

four broad groups.

Inhibitors of electron transport chain. Inhibitors of enzymes.

Inhibitors of nucleic acid metabolism and

protein synthesis.

Inhibitors of sterol synthesis.

A typical cell and cell components


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A typical cell and cell components

Electron transport chain

Enzymes

Nucleic acid metabolism

and protein synthesis

Sterol synthesis


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Inhibition of electron transport chain

(Respiration in mitochondria) Sulfur

Disrupts electron transport along the

cytochromes

Strobilurins (azoxystrobin, kresoxim-methyl,pyraclostrobin, trifloxystrobin)

Inhibit mitochondrial respiration, blocking the

cytochrome bc1 complex.


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Synthesis from Natural Products


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Oudemansin A

O

OO

O

Strobilurin A

OO

O

Enol ether stilbene

OO

O

Enol Ether Group

CN

O O

N N

OO

O

Oxime Ether Group

O

OON

O

Synthesis from Natural Products

Inhibition of enzymes


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Inhibition of enzymes

Copper

Nonspecific denaturation of proteins andenzymes.

Dithiocarbamates(maneb, manzate, dithane, etc)

Inactivate SH groups in amino acids, proteins

and enzymes.

Substituted aromatics(chlorothalonil, PCNB)

Inactivate amino acids, proteins and enzymes

by combining with amino and thiol groups.

Organophosphonate(fosetyl-Al)

Disrupts amino acid metabolism.


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Inhibition of nucleic acid metabolism

and protein synthesis

Benzimidazoles(thiophanate-methyl)

Inhibit DNA synthesis (nuclear division).

Phenylamides(mefenoxam) Inhibits RNA synthesis.

Dicarboximides(iprodione, vinclozolin)

Inhibits DNA and RNA synthesis, cell divisionand cellular metabolism.


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Inhibition of sterol synthesis

(Inhibit demethylation of ergosterol)

Ergosterol is the major sterol in most fungi.

It is essential for membrane structure and function.


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Sterol inhibiting fungicides

Imidazoles(imazalil)

Triazoles(propiconazole, myclobutanil,

tebuconazole, triflumazole) Morpholines(dimethomorph)

Inhibits sterol production at different site than

imidazoles and triazoles. Affects cell wall

production.


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Biological control of plant

pathogensChristine Roath

O i


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Overview

What is biological control, what are thebenefits to its use

Mechanism of biological control

Requirements of successful biocontrol

Working example of biocontrol

What is biological control?


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What is biological control?

First coined by Harry Smith in relation tothe biological control of insects

Suppression of insect populations by native or

introduced enemies Generic terms

A population-leveling process in which the

population of one species lowers the numberof another


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Why use biological control?


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Why use biological control?

WILL: Chemical pesticides

Implicated in ecological, environmental, and human healthproblems

Require yearly treatments

Broad spectrum Toxic to both beneficial and pathogenic species

BUT:

Biological control agents Non-toxic to human

Not a water contaminant concern Once colonized may last for years

Host specific Only effect one or few species


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Mechanisms of biological control of


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g

plant pathogens

Destructive mycoparasitismtheparasitism of one fungus by another

Direct contact

Cell wall degrading enzymes Some produce antibiotics

Example

Trichoderma harzianum, BioTrek, used as seedtreatment against pathogenic fungus

Requirements of successful


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q

biocontrol

1. Highly effective biocontrol strain must beobtained or produced

a. Be able to compete and persist

b. Be able to colonize and proliferatec. Be non-pathogenic to host plant and

environment



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q

biocontrol

2. Inexpensive production and formulationof agent must be developed

a. Production must result in biomass with

excellent shelf liveb. To be successful as agricultural agent must

be

i. Inexpensive

ii. Able to produce in large quantities

iii. Maintain viability



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biocontrol

3. Delivery and application must permit fullexpression of the agent

a. Must ensure agents will grow and achieve

their purpose

Coiling of Trichodermaaround a pathogen.(Plant Biocontrol by Trichoderma spp. IlanChet, Ada Viterbo and Yariv Brotman)


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Plant pathogen control by


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Trichoderma spp.

How is it applied?

Favored by presence of high levels of plant roots

Some are highly rhizosphere competent

Capable of colonizing the expanding root surface

Can be used as soil or seed treatment

http://www.nysaes.cornell.edu/ent/biocontrol/pathogens/images/trichoderma3.jpg



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Trichoderma spp.

Action against pathogenic fungi

1. Attachment to the host

hyphae by coiling

a. Lectin-carbohydrate

interaction

(Hubbard et al., 1983. Phytopathology 73:655-659).



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Trichoderma spp.

Action against pathogenic fungi

2. Penetrate the host cell walls by

secreting lytic enzymes

a. Chitinases

b. Proteases

c. Glucanases

(Ilan Chet, Hebrew University of Jerusalem).



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Trichoderma spp.

Some strains colonize the root withmycoparasitic properties

Penetrate the root tissue

Induce metabolic changes which induceresistance

Accumulation of antimicrobial compounds



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Trichoderma spp. Commercial availability

T-22 Seed coating, seed pieces, transplant starter

Protects roots from diseases caused by Pythium,Rhizoctoniaand Fusarium

Interacts with the Rhizosphere, near the root hairs

and increases the available form of nutrients

needed by plants.


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SUSTAINABLE MANAGEMENT OF

SOIL-BORNE PLANT DISEASES

a reduc t ion of


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a reduc t ion of

biod ivers i ty of

so i l organisms

Soi l-borne

diseases

Resto r ing beneficial

organism s that attack,

repel, or o therwise

antagonize disease-causing pathogens w i l l

render a soil disease-

suppressive

Plants grow ing in

disease-sup pressive soi l

resist diseases much

bet ter than in so i ls low inbio log ical divers i ty.

Benef ic ial organisms can be

added d irect ly, or the soi lenv i ronment can be made mo re

favorable for them throug h us e

of compost and other organic

amendments.

Compost qual itydetermines its

effectiv eness at

suppress ing

soi l-borne plant

diseases.

Why Disease?


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yPlant diseases result when a susceptible host

and a disease-causing pathogen meet in a

favorable environment

If any one of these threeconditions were not met,

there would be no

disease.


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Many intervention practices (fungicides,methyl bromide fumigants, etc.) focus on

taking out the pathogen after its effects

become apparent.

How to emphasizes on making the

environment less disease-favorable and thehost plant less susceptible.


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Documents

Kuliah Fitopat Disease Progress