Phytopathology is the study field of plant diseases caused by pathogens and physiological factors. Plant pathology involves the study of pathogen identification, disease etiology, disease cycles, economic impact, epidemiology, plant disease resistance, effects on humans and animals and disease management. Phytopathology
keywords Plant Pathology : The study of plant diseases Plant Disease : Any physiological or morphological change in a plant that results in abnormal appearance or development Pathogen : An organism that causes disease Host: The infected plant Symptom : Abnormal appearance of a plant
Components of a Plant Disease - Conducive Environment - Susceptible Host - Virulent Pathogen - Adequate Time
WSU Extension San Juan County DISEASE Pathogen Susc. Host Environment Time Components of a Plant Disease Time DISEASE Environment Pathogen Susc. Host Components of a Plant Disease
Rusts Cause: Fungi Symptoms: Fungal spore masses in yellow, orange, white, brown, and black on leaves and stems
Rust ribes host Fungus requires two host to complete its life cycle. One part on Pinus and the other on Ribes.
Cankers Cause: Fungi or bacterial infection resulting in dead, non-growing areas on stems and branches Symptoms: Dark, sunken areas with distinct margins on stems sometimes have small red or purple fruiting bodies Same fungi also cause fruit rots (e.g. bulls-eye rot)
Fungal apple Anthracnose Notice sunken (dead) areas of trunk that have failed to grow and inrease in girth as the rest of the trunk (results in depressed canker)
Root Rots Cause: Fungi ( Armillaria, Phytophthora, Sclerotinia ) and bacteria ( Erwinia ) Symptoms: Shoot wilting, chlorosis/necrosis Stem and root discoloration Dead roots often with fungal hyphae growth under bark
Inability to uptake iron from pH neutral or basic soils. Not related to amount of iron (Fe) in soil.
Irregular watering appears as a brown spot at the base of the tomato fruit, this develops into a hard, sunken ring, caused by insufficient calcium flow.
<ul><li>Disease control </li></ul><ul><li>Chemical treatments </li></ul><ul><li>Biocontrol methods </li></ul><ul><li>Development of resistant plant </li></ul><ul><li>- Cultural practices: crop rotation, good soil drainage, proper handling of the crop, adequate storage and efficient post-harvest operations </li></ul>
Direct confrontation Temperature effect on the antagonistic bacterial activity B31 B8 B29 B12 B42 B31 B12 B29 B42 B8 B8 B29 B42 B12 B31 T 19°C T 30°C T 25°C
Percentage of inhibition Strains Bacterial antagonisme °c °c °c
Inhibition de la croissance mycélienne par les protéines de la souche B8 A: mycelium growth inhibition ( 70.80% ) by bacterial protein of B8 ( proteins are at 0.356µg /well). B: mycelium development on PDA medium without bacterial extract proteins. A B
Effet of the proteine treatment on the disease development Indice of the disease Days
A. in situ initiation of callogenesis from ovules explants by transversal cutted of younger fruits; B. white cals proliferation from ovular explants; C. development of the isolateds cals on MS+NAA; D. green organogenesis cal. in situ induction and development of ovular cals A B D C
A : adventive buds formation from ovular cals on MS+BAP; B : young shoot formation from ovular cals on MS+BAP medium . Formation of structural organogene cal from ovulair explants A B
Artificial MS medium. Dicotylydonary embryos cal obtained from styl explant.
A : Friable cal with embryogenic structures B : Initiation of the rhizogenic structures. D : developed root from friables cals Organogenesis obtained from no zygotic parts of seeds A B C
Plant regeneration from friable cals induced from non zygotic parts of the seeds A: shoot regeneration on MS+BAP+2,4-D medium; B: young plant regenerated from friable cals; C: Vitroplant de Citrus eurêka developed in vitro on MS medium. B A C
<ul><li>Mal secco : Vasculare disease, Tracheomycosis </li></ul><ul><li>- Causal Agent: Phoma tracheiphila (Ciccarone, 1971) </li></ul><ul><li>- Hot: Citrus limon </li></ul><ul><li>- Geographic distribution: </li></ul><ul><ul><li>Mediterranean sea region </li></ul></ul><ul><ul><li>Black sea costs </li></ul></ul>Citrus Mal Secoo
Highly contaminated Zones Lower contaminated Zones Geographic Distribution of the Mal secco disease
A: Pycnidia of P. tracheiphila on lemon dying shoot; B: M ucilaginous pycnidia gel (the cyrrhus) containing pycnidiospores. A: Mycelium; B: Pycnidium; C: Phialoconidia; D: Arthroconidia; E: Pycnidiospores Total lemon diedback caused by the fungal infection A D B C E A B
Dissemination <ul><li>Conidia transportation </li></ul><ul><li> - Anemophilous </li></ul><ul><li> - by water </li></ul>- Entomophily <ul><li>vegetable material exchanges (Homme) </li></ul>- By birds
Phoma tracheiphila DPR DP R Pycnides Red Pigment Pycnides Absence of red pigment Sterile Red Pigment Types of P. tracheiphila
Morphological varaibility of P. tracheiphila isolates
Empirical scale of evaluation 0 : No drying symptoms 1 : Limited drying to the annual shoots 2 : Drying reach the two years branches 3 : Drying exceeded to the main branches 4 : Trunk drying 5 : Total drying and death of the infected plant
Inoculations Methods Foliar inoculation Stem inoculation Root inoculation Foliar inoculation 0= No symptoms; 1= Chlorosis on the inoculation point; 2= Chlorosis around the inoculation point; 3= Chlorosis extended till the foliar borders; 4= general chlorosis; 5= foliar necrosis. Stem and root Inoculation 0= No symptoms; 1= Chlorosis at principal vein of the upper leaves; 2= General chlorosis of the upper leaves; 3= Apical necrosis of the branches; 4= Necrosis extended to the trunk of the inoculated plant; 5= Total necrosis and death of the inoculated plant.
<ul><ul><li>In vitro artificial infection disease system </li></ul></ul>
VR Te VPt V11 V21 VH2 V13 Foliar phytotoxicity toxin Test V13: Isolat de G1 VH2: Isolat de G2 V21: Isolat de G3 V11: Isolat de G4 VR: Isolat de G5 VPt: Isolat de G5 Te: non treated by the toxin
Development of new technic of artificial reproduction of the disease Parameters: 1- Micropropagated stem necrosis (Fig. a) 0= No symptomes; 1= Necrosis under the 1/3 of the micropropagated stem; 2= Necrosis between 1/3 et 2/3 of the micropropagated stem; 3= Necrosis exceed 2/3 of the micropropagated stem; 4= Total necrosis of the micropropagated stem. 2- Inhibition of the regeneration (Fig. b) 0= No regeneration; 1= Initiation of regeneration; 2= Young shoot; 3= shoot with foliar formation . 2 0 1 3 b a