Vegetable Diseases: Identification & Management 2012 Home Vegetable Gardening Series

1.Diagnostic principles 2.Practical means of identification 3.Practical means of protection or avoidance 4.Standard and organic remedies for the most common pests and diseases 5.Resources and references

DiseaseDisorderDamage Irritation Continuous Transitory Contagious YesNo Causal agent BioticAbioticBiotic & Abiotic

 Fungi  the “Water Molds”  Nematodes  Bacteria  Actinomycetes  Phytoplasmas  Viruses  Viroids

 Insufficient soil moisture  Excess soil moisture  Oxygen deprivation  Soil compaction  Temperature extremes  Air pollution  Salinity  Soil pH  Nutrient deficiency  Nutrient toxicity  Improper cultural practices

 Primary symptoms  the first symptoms to appear  generally occur at or near the infection site  Secondary symptoms  the subsequent symptoms that appear  generally occur some distance away from the infection site Disease Identification

 Symptoms: visible alterations of the host as a result of disease  Signs: physical manifestation of the pathogen itself in or on diseased tissues Disease Identification

 Plant parts affected  Sequence of events in the development of symptoms  Pattern of disease development  Association with:  terrain  weather  plant development  other plants

The Disease Cycle (The Infection Chain)

Monocyclic disease development Pathogen goes through one (or very few) generations during the growing season (or dispersal is limited) Amount of disease is related to amount of initial inoculum Polycyclic disease development Pathogen goes through many generations during the growing season (and dispersal is not limited) Amount of disease is related to the rate of growth, reproduction and spread of the pathogen

Infection period: the time required for infection to occur under favorable environmental conditions Incubaton period: the time from penetration of the host by the pathogen to the first appearance of symptoms Latent period: the time from the beginning of the infection process to the first appearance of secondary inoculum Infectious period: the time during which a pathogen is reproducing and capable of being dispersed

Penetration Inoculation Infection Dispersal Colonization Reproduction

Penetration Inoculation Infection Dispersal Colonization Reproduction

Penetration Inoculation Infection Dispersal Colonization Reproduction

Penetration Inoculation Infection Dispersal Colonization Reproduction