Agriculture Reference
In-Depth Information
Chapter 2
Managing crop disease through
cultural practices
Dale Walters
Scottish Agricultural College, Edinburgh, UK
2.1
Methods used to control plant disease vary depending on the host plant, the type of
pathogen, the interaction between the two, as well as a range of other factors including
environmental conditions. Most control methods are aimed at protecting crops against
pathogens rather than curing them once they have been infected. Cultural control falls
into this category, since it aims to prevent contact with the pathogen, to create environ-
mental conditions unfavourable to the pathogen or at least to avoid favourable conditions,
or to reduce the amount of pathogen inoculum available to infect crop plants. Methods
used for cultural control include host eradication, crop rotation, sanitation, irrigation, till-
age and improving crop growth conditions, for example through appropriate fertiliser use.
Cultural control provides the foundation for disease control in crops and yet its impor-
tance is often overlooked. This chapter aims to provide an overview of the various cultural
methods used to control crop disease and to highlight the importance of these methods in
improving crop health and productivity.
Introduction
2.2
Reducing the amount of pathogen inoculum
2.2.1
Host eradication
Host eradication, or roguing, refers to the removal and disposal of whole infected plants.
This method is used routinely in nurseries, greenhouses and fi elds to prevent the spread
of pathogens, since it eliminates the infected plants that act as a source of inoculum.
In potato cultivation, pathogens can overwinter in infected tubers left in the fi eld and
give rise to infected plants (known as volunteers) in the spring. These volunteers can
act as sources of inoculum and their removal from the fi eld and subsequent destruction
will reduce levels of pathogen inoculum. Eradication has also been used on a somewhat
larger scale to stop the spread of destructive pathogens. Continual vigilance is required,
however, since the pathogen may reappear. For example, Sharka disease caused by the
Plum pox virus
(PPV) was fi rst detected in Switzerland in 1967. By the end of the 1970s,
PPV was thought to be successfully eradicated through a combination of survey work
