4 Introduction to Plant Pathogens - Copy

4 Introduction to Plant Pathogens - Copy - PP 315 / 590J...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
PP 315 / 590J  Lecture 4 Introduction to Plant Pathogens Objectives Become familiar with the various types of plant pathogens. The major groups of biotic plant pathogens  and parasites include fungi, Bacteria, Viruses, Nematodes and Parasitic seed plants. Study a brief  comparison of these "organisms" (a virus is not an organism) in order to help set the stage for  understanding the upcoming lectures on  pathogenesis  (the steps in disease development) and disease  management. FUNGI Fungi is by far the most common group of organisms that causes disease in plants, and we will  emphasize many principles and concepts of plant disease development and control based on fungal  diseases. FUNGI  - (singular = fungus) -- eucaryotic, heterotrophic organisms that have a vegetative stage  composed of a single cell or more commonly a filamentous thallus, and which usually reproduces by the  production of spores The vegetative stage of most of the fungi that we study in this class consists of thread-like filaments called  hyphae  (sing. = hypha). Most groups of fungi have hyphae with  septa  (sing. = septum) or cross walls produced at regular  intervals. These hyphae are called  septate . Some fungi or fungal-like organisms do not have septa, and the hyphae are called  coenocytic  (aseptate).  Septations are only produced to wall-off old hyphae or spores. When a nutrient substrate is present, hyphae branch profusely, and this mass of hyphae is referred to as  mycelium . In pure culture, fungi grow in distinct patterns and the mycelium is referred to as a  colony . Most fungi reproduce by the production of spores. A spore can be asexual or sexual in origin. If present, 
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/22/2008 for the course PP 315 taught by Professor Shew during the Spring '08 term at N.C. State.

Page1 / 3

4 Introduction to Plant Pathogens - Copy - PP 315 / 590J...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online