Agriculture Reference
In-Depth Information
Chapter 11
Plant disease control by nutrient
management: sulphur
Silvia Haneklaus, Elke Bloem and Ewald Schnug
Institute for Crop and Soil Science, Julius kühn Institut,
Federal Research Centre for Cultivated Plants, D-38116 Braunschweig, Germany
11.1
Introduction
In 2006, more than 30 000 tonnes of herbicides, insecticides and fungicides were used
in Germany; the total number of approved pesticides was 665 in the same year (Anon,
2006). Although the risk of health impairments by combination toxicology has been rated
as insignifi cant (Carpy
et al.
, 2000), contamination of foodstuffs with pesticide residues
is a particular threat for the health of children (Goldman & Koduru, 2000). A growing
public concern about adverse health effects of pesticides and environmental issues has
led to an increasing demand for products from organic farming. However, not only in
organic farming, but also in conventional agriculture, there is an increasing interest in
alternative methods for disease control. These imply soil tillage operations, plant cultiva-
tion practices, plant breeding and plant nutrition, of which the latter will be addressed in
this chapter.
11.1.1
Nutrient-induced resistance against diseases
It was Justus von Liebig (1873), who initially identifi ed the nutritional status of a plant
as being one of the key factors regulating its susceptibility against diseases. Interactions
between mineral elements and plant diseases are well known for essential macro and
micro plant nutrients, and aluminium and silicon (Datnoff
et al.
, 2007). Although the
signifi cance of individual nutrients for maintaining or promoting plant health saw some
interest in the 1960s and 1970s (Bergmann, 1983), research in the fi eld of nutrient-induced
resistance mechanisms has been limited by its complexity and its practical signifi cance
remained unrecognised due to the availability of effective pesticides. Substantial progress
in identifying the underlying triggers and processes of nutrient-induced resistances against
plant diseases can be expected since elaborate analytical facilities, all coming under the
term 'omics', for example, ionomics and metabolomics, are available nowadays.
The mineral nutrient supply is supposedly the primary and pivotal barrier against
infection, which also infl uences the course of pathogenesis. In general, the greatest
benefi t to the plant in terms of health can be expected when full nutrient suffi ciency is
