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Identification of Powdery Mildew Fungi - Lab Sheets
     
     
   

(LAB SHEETS TO BE PRINTED AND FILLED OUT BY STUDENTS)

OBSERVATIONS

Diagram the conidiophores and conidia seen on the diseased leaf.

In the table below, record the location of conidiophores, the type of conidia formation, the number of asci per chasmothecium, and a description of the appendages found on the chasmothecium. Using this information, determine the pathogen genus for each powdery mildew.

Plant host

Conidiophores (arising from epiphytic hyphae or emerging through stomata)

Conidia formation (singly, or in chains)

# of asci per chasmothecium (one or several)

Appendage morphology

Pathogen genus

           
           
           
           
           

CONCLUSIONS AND QUESTIONS

  1. What physiological functions of the plant are impaired by powdery mildew fungi?
  2. What is the function of the chasmothecium in the disease cycle?
  3. What is the function of the conidia in the disease cycle?
  4. Why are fungal pathogens frequently assigned to more than one genera? Why is the generic name based on the holomorph (whole fungus) concept important in the powdery mildews?
  5. Speculate as to why free water on the surface of a plant might be unfavorable to a powdery mildew pathogen.