Agriculture Reference
In-Depth Information
10.10
Solarization and the MB crisis
Soil fumigation with chemicals may have negative effects on the environment, thus leading
to their phase-out, as in the case of MB. As a consequence, farmers are left in desperate
need of innovative and environmentally accepted alternative approaches. Indeed, SH has
replaced MB in certain hot regions of the world and it continues to be further adopted
as an alternative to MB, particularly in combination with another technique(s). In Costa
Rica, for example, an estimated 20% of the melon cropping area (about 2000 ha) is now
being solarized, and this has proven particularly successful when combined with reduced
doses of metham sodium (MBTOC, 2007). Solarization is also widely used in Greece and
Turkey. Improving solarization performance by combining it with fumigation could solve
many problems, since such combinations are suitable for areas deemed marginal for the
application of solarization alone.
In recent years, several studies have examined the effects of long-term, large-scale use
of SH and organic amendments on weed populations, nematodes, yields and soil fertility
with peppers (
Capsicum annuum
) and cucumbers (
Cucumis sativus
) (Roe
et al.,
2004;
Ozores-Hampton
et al.,
2005). Benlioglu
et al.
(2005) studied solarization in Turkey and
compared it to chemical treatments to control
Rhizoctonia
spp.,
Phytophthora cactorum
and
V. dahliae
in strawberry production. Solarization provided 163% higher yield than
the control and over 50% more than a high rate of the fumigants tested. SH was shown
to be cost-effective, compatible with other pest-management tactics and a valid alter-
native to pre-plant fumigation with MB under the tested conditions in Florida (Chellemi
et al
., 1997).
The MB phase-out showed that dependence on a single method or chemical can lead
to an agricultural crisis. Thus, integrated approaches are the best solution for pest control.
Solarization can be a major component in such integrated programs.
10.11
Concluding remarks
Today, the biggest challenge in crop protection sciences is to effectively control pests,
while avoiding environmental hazards and degradation of natural resources. SH is an
additional tool for achieving this task, when it is used in appropriate situations. Although
the positive effects of SH outweigh the negative ones (e.g. plant-growth retardation due
to harmful effects on benefi cial microorganisms, such as
Rhizobium
or mycorrhizae),
the emphasis in research should be placed on the negative effects and on developing
means to detect and avoid them. After more than 130 years of soil disinfestation, the
arsenal of chemical disinfestants is still very limited, and the arsenal of non-chemical
agents for soil disinfestation even more so. Therefore, the integration of pest manage-
ment methods, rather than relying on one powerful control agent, is not only desirable
but also the only feasible solution for coping with our need for methods of controlling
soil-borne pathogens in an atmosphere of environmental awareness, concerns, and pres-
sure. SH is needed not only as an alternative to MB, but also for many other purposes.
There are many challenges awaiting the further development of SH: improvements in
implementation technology and control effectiveness, thereby shortening the mulching
period and extending the period for solarization; a better understanding of control mecha-
nisms which can lead to more effective disturbance of the pathogens' life cycles; further
