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1.1 Introduction to integrated disease management •Introduction •Effects of control measures on disease progress •Effects of control measures within the plant tissue •Translocation and deposition of control measures •When to apply a control measure? •Concluding remarks Plant life cycle Seed dissemination Seed formation Seed germination reproductive growth Seedling establishment Vegetative growth Pathogen life cycle spore dissemination spore formation spore germination reproductive growth establishment lesion formation Plant and pathogen life cycles seed dissemination seed formation seed germination reproductive growth seedling establishment vegetative growth Monocyclic pathogens Complete only one disease cycle in a growing season Q = amount of initial inoculum dy R = infection efficacy of the inoculum dt y = disease intensity (%) QR (100 - y) Logit = ln ( Time Disease intensity (logit) Disease intensity (%) t = time QR Time 100 100-y ) For monocyclic pathogens Disease intensity (%) All disease plants are infected from inoculum that survived from the previous season Time Pathogens are monocyclic because: The host is susceptible for a very short tine (smuts) The infecting structures do not disseminate within the same growing season (soil-borne pathogens) The environmental conditions are conducive for infection for a short time (scab) The growth of the pathogen is very slow Polycyclic pathogens Complete several disease cycles in a growing season r = apparent infection rate dy y = disease intensity (%) dt r y (100 - y) t = time Disease intensity (logit) Disease intensity (%) Logit = ln ( r Time Time y 100-y ) For polycyclic pathogens Disease intensity (%) Few plants are infected from inoculum that survived from the previous season Most plants are infected from inoculum that was proliferated within the current season Time Control measures Chemical Cultural Biological Genetic Induced resistance “Strategic means”: Means that are applied once, and their effect is apparent for a long time (the entire growing season) “Tactical measures”: Means that are applied frequently, and are effective for a relatively short time The effects of control measures on disease development Depends on the biology of the pathogen (monocyclic or polycyclic) and on the characteristics of the measure (strategic or tactical) Monocyclic pathogens Polycyclic pathogens Disease intensity (%) Disease intensity (%) Time Disease intensity (logit) Time rate Initial disease Time Disease intensity (logit) Possible effects of control measures on disease progress Effects on the amount of initial disease Time Soil treatment Seed treatment Systemic fungicides Crop rotation Certified seeds Sanitation Escape (planting time) Biocontrol agents Disease intensity (logit) Possible effects of control measures on disease progress On the rate of disease development In monocyclic pathogens: on the infection efficacy of the inoculum Time Protectant fungicides Systemic fungicides Polycyclic pathogens: Effects on the apparent infection rate Genotype resistance cultural measures (e.g., heating, ventilation) Biocontrol measures Disease intensity (logit) Possible effects of control measures on disease progress Effects on the amount of initial inoculum and Time Systemic fungicides On the rate of disease development Integration of control measures Deposition and translocation of control measures Within treated leaves Within treated plants Deposition and translocation of control measures within treated leaves Deposition and translocation of control measures within treated leaves Protectant measure Mesostemic measure Trans-laminar measure Deposition and translocation of control measures within treated leaves Systemic measure Measures with re-distribution ability Deposition and translocation of control measures within treated plants Application of a systemic measure to the root system Deposition and translocation of control measures within treated plants Application of a systemic measure to the stem Deposition and translocation of control measures within treated plants Application of a systemic measure to a leaf Deposition and translocation of control measures within treated plants Application of a systemic measure to the foliage of a growing plant Integration of control measures Application according to the expected efficacy of each measure Alternated application Combined application Time Combined efficacy of control measures Synergistic Antagonistic Control efficacy (%) Additive 1 2 1+2 exp. 1+2 obs. 1+2 obs. 1+2 obs. Control efficacy (%) Calculation of combined efficacy of control measures - Step 1 A = control efficacy of #1 B = control efficacy of #2 A+B(obs.)= observed control efficacy of 1+2 1 2 1+2 1+2 obs. exp. A+B(exp.)= expected control efficacy of 1+2 Abbott formula E (exp)= A + B - (A*B)/100 Calculation of combined efficacy of control measures - Step 2 Control efficacy (%) SF = E (obs) / E (exp SF = Synergy factor E(obs.)= Observed control efficacy of 1+2 1+2 exp. 1+2 obs. E(exp.)= Expected control efficacy of 1+2 Combined efficacy of control measures SF = Synergy factor SF > 1 synergistic 1+2 1+2 exp. obs. SF < 1 antagonistic Control efficacy (%) Control efficacy (%) Control efficacy (%) SF = 1 additive 1+2 1+2 exp. obs. 1+2 1+2 exp. obs. Combined efficacy of control measures Treatment Disease severity (%) E = 100-(t/c)*100 1 20 control efficacy of #1 = 100-(20/80)*100= 75% 2 30 control efficacy of #2 = 100-(30/80)*100= 62.5% 1+2 15 control efficacy of 1+2= 100-(15/80)*100= 85% Control 80 Abbott formula E (exp)= A + B - (A*B)/100 E (exp)= 75+62.5 - (75*62.5)/100=90.6% Combined efficacy of control measures E(obs.)= Observed control efficacy of 1+2 E(obs.)= 85% E(exp.)= Expected control efficacy of 1+2 E(exp.)= 90.6% SF = E (obs) / E (exp SF = 85 / 90.6 = 0.93 SF < 1 antagonistic reaction When to apply a “tactical” control measure? Effects of the environment on the pathogen Effects of the control measure on the pathogen’s life cycle Effects of the host on the pathogen When to treat? Effects of the environment on the pathogen grower host environment pathogen When to treat? Effects of the environment on the pathogen Rain Periods of high relative humidity High or low temperatures Hail Sand storms Disease intensity (%) Environmental factor Environmental factors Time When to treat? Effects of the environment on the pathogen spore dissemination reproductive growth spore germination Disease severity (%) spore formation establishment Time lesion formation When to apply a “tactical” control measure? Effects of the environment on the pathogen Effects of the control measure on the pathogen’s life cycle Effects of the host on the pathogen When to treat? Effects of the control measure on the pathogen control measure host environment pathogen When to treat? Effects of control measures on the pathogen’s life cycle spore dissemination spore formation Protectant fungicides, biocontrol agent, heating, ventilation reproductive growth spore germination establishment lesion formation When to treat? Effects of control measures on the pathogen’s life cycle spore dissemination spore formation spore germination Mesostemic fungicides, biocontrol agents, genotype resistance reproductive growth establishment lesion formation When to spray? Effects of fungicides in the pathogen’s life cycle spore dissemination spore formation spore germination Systemic fungicides, biocontrol agents reproductive growth establishment lesion formation When to treat? Effects of control measures on the pathogen’s life cycle spore dissemination spore formation spore germination Curative fungicides, heating, ventilating, light filters reproductive growth establishment lesion formation When to treat? Effects of control measures on the pathogen’s life cycle spore dissemination spore formation spore germination Eradicative fungicides, biocontrol agents, ventilation, heating reproductive growth establishment lesion formation When to apply a “tactical” control measure? Effects of the environment on the pathogen Effects of the control measure on the pathogen Effects of the host on the pathogen Host resistance When to treat? Effects of the host: age-related resistance grower host Time pathogen Disease intensity (%) environment Time Concluding remarks Application of control measures should be based on: The biology of the pathogen (monocyclic, polycyclic) The possible activity of the control measure (protectant, mesostemic, translaminar, systemic) The relationships between the host, the pathogen and the environment: effects of the environment on the pathogen effects of the control measures on the pathogen effects of the host on the pathogen