Ecological Interactions and Biological Control

By David A. Andow; David W. Ragsdale et al. | Go to book overview

favorable conditions for disease development, can negate beneficial effects of amendments. Also, there are trade-offs: Papavizas ( 1966) found that cruciferous amendments reduced Aphanomyces root rot but increased Rhizoctonia root rot on pea.

Soil and environmental factors profoundly affect decomposition and effectiveness of organic amendments in disease control ( Lumsden et al. 1983b). Soil types differ in chemical and physical properties and in biological composition. Among a multitude of factors, temperature, moisture, and aeration critically affect the decomposition process, microbial activity, and the by-products that are formed.


Conclusions

Organic amendments consist of plant residues, green manure crops, constituents of plant or animal residues, animal manures, composts, and formulations. Organic amendments affect pathogens as a direct food source, stimulate antagonistic organisms, and improve the physical properties of soil and nutrient status of the crop, which can enhance disease resistance. The succession of organisms that utilize a substrate during decomposition affect the activity, survival, and population of pathogens and disease suppression through antibiosis and lysis, competition, parasitism, or predation. Populations of soil bacteria (including actinomycetes) and fungi are affected by the type and maturity of the amendment, kinds and amounts of decomposition products, proportion of available nutrients in relation to resistant components, carbon to nitrogen ratio of soil, and the physical and chemical environment.

Considerable evidence has accumulated to show that application of organic amendments has potential, and is a feasible approach, to control plant diseases. However, the effects are usually indirect. That is, amendments affect plants and soil microorganisms that in turn affect pathogens and disease. Moreover, certain combinations of host and pathogen behave differently in response to organic amendments and must be studied individually to arrive at practical disease control measures. Part of the difficulty in making recommendations is that more information is needed to elucidate factors that affect disease development in specific host-pathogen combinations in relation to organic amendments, as well as factors that affect the ecology of soil microorganisms. Current information suggests that complete control of any disease depends on a combination of environmental and biological inputs, of which organic amendments is but one. It is imperative to understand how organic amendments alter the physical, chemical, and biological composition of soil so that optimal plant productivity and consistent, effective control of soil-borne plant pathogens can be attained.


References

Adams, P. B. 1971. "Effect of soil temperature and soil amendments on Thielaviopsis root rot of sesame". Phytopathology 61:93-97.

-296-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Ecological Interactions and Biological Control
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen
/ 340

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.