Agriculture Reference
In-Depth Information
Many studies have combined control methods with solarization, frequently with
good results. Such combinations may result in either synergistic or additive effects. The
previously described weakening phenomenon is such a mechanism, potentially leading to
synergism, or to improved control.
Combining methods of control is more than just mixing two methods. The combination
has to be optimal. For example, combining short SH (for 10 days) with a reduced dosage
of MB or metham sodium resulted in higher effectiveness in controlling pathogens than
each method alone. However, if solarization was applied fi rst and MB afterwards, this
combination was much more effective than when the opposite sequence was applied
(Eshel
et al.,
2000).
Certain elements of integrated management are powerful tools for improving
solarization. Therefore, combining solarization with other methods of control enables
us to address the limitations of the former, that is climate dependency, uncertainty due
to climatic variations, occupation of the mulched soil with plastic for 4-6 weeks and the
inability of solarization to control thermotolerant pathogens, for example,
Macrophomina
,
Monosporascus
and possibly others. Examples will be given below.
Solarization can also be combined with cultural methods. For example, combining
solarization with a certain crop sequence improved the control of Fusarium wilt of cotton
(Katan
et al.,
1983).
10.5.1
Combining solarization with fumigants
Combining solarization with a fumigant has many potential advantages: improved con-
trol due to heating of the chemical and consequently allowing a reduction in fumigant
dosage, and cost reduction because the same plastic can be used for both purposes: solar-
ization and fumigation. Combining solarization with chemicals at reduced dosages, or
other measures, for example biocontrol agents, can reduce the limitations of solarization.
The control effi cacy may be increased due to additive effects, or to a synergistic effect
caused by the hotter environment, which increases vapor pressure and chemical activity
of the added pesticide. Another possible mechanism for improved activity of the pesticide
is weakening of the pathogenic resting structure by heat. Solarization combined with
fumigants could shorten the required duration of solarization, thus making the method
more acceptable for farmers. A combination of solarization and metham (Ben-Yephet
et al.,
1988) killed more propagules of
F.
oxysporum
f. sp.
vasinfectum
, and faster than
solarization alone. Thus, the period during which solarization is effective might be longer
than previously thought, when a suitable improvement, in the form of combined treatment,
is made. There are many other examples. Furthermore, sublethal fumigation in combina-
tion with solarization is especially useful for areas that are marginal for the application
of solarization. Studies on combining solarization with other chemical or non-chemical
methods include those combining solarization with MB for controlling yield decline in
Gypsophila
(Gamliel
et al.,
1993). An MB-chloropicrin mixture combined with solariza-
tion was effective in controlling
Pseudomonas
solanacearum
in tomato (Chellemi
et al.,
1994). Additional examples are combining solarization with dazomet for the control of
pink root of onion (Porter
et al.,
1989), or metham sodium for the control of delimited
shell spot of peanut (Frank
et al.,
1986) and soil-borne diseases of strawberry (Hartz
et al.,
1993). Combining fumigants with SH under virtually impermeable fi lms improved
