Biocontrol and IPM

Reading Assignment: Chapters 34 and 35

Biocontrol Control of plant pathogens with other microbesControl of plant pathogens with other microbes A biological control agent is known as an antagonistA biological control agent is known as an antagonist Antagonism is general name for mechanisms of biological controlAntagonism is general name for mechanisms of biological control

Antagonism

Antibiosis

Competition

Parasitism

IPM IPM is the management of diseases by optimizing control strategies to prevent diseases from causing economic lossesIPM is the management of diseases by optimizing control strategies to prevent diseases from causing economic losses Purpose of disease control: prevent disease damage from exceeding level where profit or required yield is significantly diminishedPurpose of disease control: prevent disease damage from exceeding level where profit or required yield is significantly diminished

How do we prevent profit losses? Reduce (delay) disease at the beginning of the season (Xo)Reduce (delay) disease at the beginning of the season (Xo) Decrease rate of disease development (r)Decrease rate of disease development (r)

When do we act?  Economic injury level: “damage threshold” – the level Xt at which disease begins to be adversely affect yield and/or quality  Level of injury may vary from one region or farmer to the next region or farmer

When do we act?  Action threshold – “Economic threshold” – pathogen density at which control measures should be taken to prevent pathogen from reaching the economic injury level  Farmer must act to reduce r so that disease dose not reach EIL before harvest

Economics  Growers can be expected to increase resources for crop protection until the amount of money expended = additional crop income

Factors that effect economic thresholds  Producers attitude  Crop income – disease incidence relationship  Control costs – pathogen population relationships

Economics  Tolerance level: amount of disease where crop income falls as disease levels increase  Income losses can result from decreased yields and/or decreased quality  How much disease can be tolerated on a poinsettia or a golf green?

What the grower should know  Value of yield  Probable cost of disease control  Cost of several alternative control measures  Efficiencies of controls in reducing disease  Expected impact of a given pathogen intensity on quality and quality of yield

What can influence farmer’s decisions?  Level of credit or affluence  Undetected crop loss  Aversion to risk