Agriculture Reference
In-Depth Information
8.1.1
Plant Pathogens and Diseases
The plants in the agricultural ecosystems, as in the natural ones, are subjected to
a wide range of pathogenic agents that cause the so called biotic stresses or, more
simply, diseases. Plant diseases can be schematized in soil, air and seed-borne ones,
depending by the type of host plant organ (hypogeal, epigean or seed, respectively)
from which the infection began. Soil-borne phytopathogens are responsible for de-
structive diseases of roots, stems and vascular tissues, occurring in a broad-spec-
trum of susceptible hosts under favorable environmental conditions.
Plant pathogens belong to several different phyla. In the plethora of microor-
ganisms, potential plant pathogens, filamentous fungi and bacteria, are among the
most feared and dangerous. This because of their extraordinary ability to survive,
conserve and diffusion themselves both in the space and in the time, even in ex-
treme conditions; to breakdown plant genetic resistance mechanisms and, finally, to
overcame toxicity of chemical compounds.
Disease occurrence generates physiological disorders in the plants that signifi-
cantly reduce yield and quality until, eventually, to cause the complete crop losses.
Therefore, for these reasons, in productive eco-systems cannot totally renounce to
an efficacious control program. The methods of disease control are always finalized
to the breaking of the disease cycle. This last is the succession of interlinked stages
occurring in the complex interaction between the virulent pathogen and the sus-
ceptible host plant that establish the pathogenesis. The more sensible phases of this
cycle to the action of the control tools include: pathogenic inoculum conservation
and dissemination; penetration, infection and spreading in the host plant; evasion
and production of propagules for future infections.
8.1.2
The Old Compost as Innovative Tool for Diseases Control
Since the agrarian crops are susceptible to many bacterial and fungal attacks, dis-
ease management is one of the most important components in the production sys-
tem. Generally, disease control is entrusted to chemically synthesized fungicides
and fumigants. When severe biotic epidemics occur, growers generally respond
with applications of broad-spectrum chemicals on a calendar basis, with up to 12
to 16 applications per season (Reitz et al.
2008
) that weights by 4.1 % on total costs
of production (Engindeniz
2006
). But, health reasons and environmental sensitivity
are driving the market towards products obtained by sustainable cropping systems,
stimulating the reduction of synthetic pesticides (banning of more dangerous ones)
and the use of alternative and eco-compatible plant disease management (Wagner
1999
). Moreover, this issue is of great relevance today in Europe, that is exploring
new directions toward integrated pest management (IPM) in the view of implement-
ing the Directive 2009/128/EC on the reducing pesticide use-and-risk in EU. In this
context, the suppressive properties of compost represent a real opportunity for the
development of a green agriculture, safe, competitive and sustainable in nature.
The compost is a complex organic matter commonly used as soil amender. This
peculiarity has prompted its utilization in the area of the plant protection mainly in
