Agriculture Reference
In-Depth Information
Viral diseases are worth a special
mention as their devastating effects have
been frequently felt. The only control
measure against these diseases is preven-
tion, unless tolerant or resistant plant
material is available. Where these dis-
eases are introduced by a vector there is a
need for strict control of the vector's
populations.
sanitary state of the plant material; and
(vi) using biologically inert substrates.
13.9
Other Aspects
Phytosanitary control costs are very variable,
depending on the cultivated species and the
general growing conditions, especially the
machinery and labour used (see Chapter 14).
For other aspects, such as control of
other pests (rodents, birds) and weeds, the
prevention of pathophysiologies, etc. the
reader should refer to the specialized litera-
ture on these subjects.
13.7 Most Common
Greenhouse Pests
Due to the non-existence of a seasonal cli-
matic break in the greenhouse, such as it
happens in cold winter areas with open field
crops, many pests are permanent, helped
by the long occupation of the greenhouses
and due to the existence of pest reservoirs in
open-air host weeds or crops, when the
greenhouse is empty.
In greenhouses, in decreasing order of
importance the Aleurodidae (white flies),
Noctuidae, thrips, leaf miners, mites and
aphids are the most common greenhouse
pests in the Mediterranean area (Aparicio
et al ., 1998). At the end of the first decade
of the 21st century, the appearance in the
Mediterranean area of the previously
unknown lepidopteran 'tomato moth' ( Tuta
absoluta ) is causing severe problems in the
tomato crop.
In general, it is easier to avoid the
growth of pest populations than to decrease
their number. Therefore, prevention is
essential.
13.10
Summary
In protected cultivation, pests and dis-
eases find favourable conditions for
their development.
The control of pests and diseases has
been based, until recently, on the use of
chemicals.
Biological control is based on the use of
natural enemies of the pests and patho-
gens, to maintain their populations
below the 'economic damage threshold'.
The development of resistance to pesti-
cides combined with general concerns
for the environment and for food safety
and health have been the main causes for
the recent move away from sole depend-
ence on chemical control to an integrated
pest management (IPM) approach.
IPM constitutes a different way of
understanding pest and disease control,
which tolerates the presence of pests
and diseases below an 'economic dam-
age threshold' and gives preference to
other types of control (biological, cul-
tural, genetic) rather than to chemical
control, which is used only as a last
resort. This allows for a notable decrease
in phytosanitary treatments.
Climatic factors directly influence the
13.8
Prophylaxis
Disinfection of the soil can be necessary in
some cases, especially in nurseries or for
pot plant production. After disinfection, it
is essential to prevent contamination by
using the following measures: (i) using foot-
baths at points of access to the greenhouse;
(ii) limiting the movement and transport of
soil particles (with plastic mulch); (iii) dis-
infecting the tools; (iv) eliminating weeds
around the greenhouse; (v) ensuring the
development of pests and diseases of
crops. Therefore, proper greenhouse
climate control can help to decrease
their development.
 
 
 
 
 
 
 
 
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