1. © 2009 Delmar, Cengage Learning Chapter 20 Greenhouse Diseases

2. © 2009 Delmar, Cengage Learning Causes Causal organisms –bacteria –fungi –viruses –phytoplasmas abiotic or noninfectious conditions

3. © 2009 Delmar, Cengage Learning Integrated Pest Management (IPM) Prevent problems Regular monitoring of crops and growing area Accurate diagnoses Appropriate action thresholds Effective management methods

4. © 2009 Delmar, Cengage Learning Disease Triangle Susceptible host Pathogenic causal organism Environment

5. © 2009 Delmar, Cengage Learning Beneficial Microorganisms Control pests Build soil structure Decompose organic material Eliminate toxins

6. © 2009 Delmar, Cengage Learning Koch’s Postulates Microorganism must be found in the organism when the disease occurs Microorganism must be isolated from the diseased organism and grown in pure culture

7. © 2009 Delmar, Cengage Learning Koch’s Postulates Cultured microorganism must cause disease when inoculated into a healthy organism Microorganism must be re-isolated from the inoculated, diseased experimental organism and identified as being identical to the original specific causative agent

8. © 2009 Delmar, Cengage Learning Fungi Characteristics –chitinous cell wall –hyphae: mycelium –reproduce by spores –heterotrophic (lack photosynthesis)

9. © 2009 Delmar, Cengage Learning Fungi Characteristics –categories obligate saprophytes obligate parasites facultative saprophytes facultative parasites

10. © 2009 Delmar, Cengage Learning Fungal Diseases Botrytis blight (gray mold) –symptoms –management

11. © 2009 Delmar, Cengage Learning Fungal Diseases Downy mildew –symptoms –management

12. © 2009 Delmar, Cengage Learning Fungal Diseases Powdery mildew –symptoms –management

13. © 2009 Delmar, Cengage Learning Fungal Diseases Soil-borne –species Pythium Phytophthora Rhizoctonia Thielaviopsis –symptoms –management

14. © 2009 Delmar, Cengage Learning Bacteria Characteristics –single-celled microorganisms –do not contain a nucleus –found in every habitat on earth

15. © 2009 Delmar, Cengage Learning Bacteria Management Diseases

16. © 2009 Delmar, Cengage Learning Viruses Characteristics –noncellular organisms –nucleic acids (RNA or DNA) surrounded by protein –reproduce in the host cell –transmitted directly through sap

17. © 2009 Delmar, Cengage Learning Viruses Symptoms Identification (ELISA) Management

18. © 2009 Delmar, Cengage Learning Phytoplasmas Characteristics –specialized bacteria (obligate plant parasites) Aster yellows –vectored by leafhoppers –management Excessive branching