Agriculture Reference
In-Depth Information
Chapter 9
Biofumigation for plant disease
control - from the fundamentals
to the farming system
John Kirkegaard
CSIRO Plant Industry, Canberra, ACT 2601, Australia
9.1
Biofumigation is a term originally coined to describe the suppression of plant pests and
diseases by biocidal hydrolysis products, notably the isothiocyanates (ITCs), released
by glucosinolate (GSL)-containing plants in soil (Kirkegaard
et al
., 1993). The term has
since been popularized to now encompass a range of benefi ts derived from these and other
organic amendments. Although the primary focus in this chapter is on recent develop-
ments to maximize the ITC-related biofumigation benefi ts as originally defi ned, a more
complete understanding of the variable disease suppression reported demands a consid-
eration of the other mechanisms operating in amended soils. Increasingly, fi eld-based
biofumigation studies are revealing a signifi cant contribution of mechanisms other than
those related to GSL hydrolysis products to the observed disease control, as well as other
system benefi ts such as improved soil structure, increased organic matter and erosion
control. Ellenby's early research (Ellenby, 1945) on the effects of
Brassica
root exudates
on potato cyst nematode (
Globodera
spp.) foreshadowed considerable contemporary
interest in the pest and disease control potential of GSL-containing plants. The phenom-
enon has been observed for centuries, but has received renewed interest recently fuelled
by the need to seek disease control alternatives to the widely used soil fumigant methyl
bromide (Martin, 2003), and a desire to reduce dependence on other synthetic pesticides.
Advances in soil and plant analytical techniques have underpinned an improved under-
standing of the fundamental processes on which to develop sound disease control strate-
gies using biofumigation and these have been extensively reviewed (Fenwick
et al
., 1983;
Chew, 1988; Brown & Morra, 1997; Rosa
et al
., 1997; Mithen, 2001; Matthiessen &
Kirkegaard, 2006). Yet a mostly empirical approach to much subsequent work and an
apparent disconnect between fundamental and applied research has limited the develop-
ment of the concept to the stage of commercial adoption (Kirkegaard & Matthiessen,
1999). Indeed in a recent review of biofumigation fi eld studies published between 1992
and 2006, only 1 out of the 18 studies reported the GSL content of the incorporated
tissue (Matthiessen & Kirkegaard, 2006). The level of commercial adoption has, until
recently, belied the heavily documented potential. A more recent systematic approach
to biofumigation and advances in species selection and plant incorporation techniques
have made it possible to generate ITC concentrations in soil more comparable to those
Introduction
