经济损害水平与经济阈值

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1、经济损害水平与经济阈值　THEKEYSTODISEASEMANAGEMENT From《EpidemiologyandPlantDiseaseManagement》byJanC.Zadoks,RichardD.Schein.NewYork1979.p350-353　Letusdefinediseasemanagementasthetotalofallactions，intentionalornot，thatservetoregulatedisease1evelssothattheyremainbelowthe

2、economicthresho1d1evel；theactionscanbedirectedtowardasinglediseaseortowardalldiseasesthreateningacrop；theactions mayormay notfintoasystemofsupervisedorevenintegratedcontro1；diseasemanagementandpestmanagementarepartsofcropmanagement，buttheymaydemandaspecific

3、expertise．Developmentofadiseasemanagementprogramdependsonknowledgeofthreeareas：cropeconomics,populationdynamics,anddiseasecontroltechnology,Withcropeconomics,weleavetheareaofnaturalsciencesandenteranareawherevaluejudgmentspertain．Althoughtheindividual’s val

4、uejudgmentmaybehighlysubjective,thescienceofeconomicsdealingwithlargegroupsofindividualsisnotso．Itistheeconomistwhostudiesthefinancialaspectsofcroplosses．Fordetaileddiscussions，refertotheappropriateliterature(Carlson，1971；Carlson&Main，1976；Ordish& Dufour，19

5、69)．Economicconsiderationsarecrucialintheprocessleadingtoadecision fororagainstaction；Valuejudgmentsbyauthorities，consumers，merchants，andfarmersplayanimportantrole．Thefarmer'sjudgmentleads，implicitlyorexplicitly，toanideaabouttheeconomicallyacceptabledamage．

6、 1TheEconomicinjurylevelorDamageThresholdThestrategyof diseasemanagementistoto1eratedisease，buttoregulateitatsubeconomiclevels.ItfollowsthatthatthelevelXtatwhichdiseasebeginstoadverselyaffectyieldand／orquality--thedamagethreshold-mustbeknown．Thelevelofthist

7、hresholdvarieswithcrop,disease，and1ocaleconomy．Onefarmerorfarmingregionmaybeabletotoleratelossofattainableyieldbetterthananotherandremaineconomicallyviable．Thefarmer'sjudgmentabouttheeconomicallyacceptabledamagemustbetranslatedintoconcomitantlevelsofXt.Such

8、studiesarestillrare;anexcellentexampleisgivenbyCalpouzosetal．(1976).ThelevelofXtatwhichthehighest，economicallyacceptabledamageoccurshasbeen calledtheeconomicinjurylevelbyentomologists：itisthelowest pop