Agriculture Reference
In-Depth Information
by solarization, for example by plotting the level of mortality versus accumulated hours
above a certain temperature, that is the degree-hours (DH) (Chellemi
et al.,
1994). Shlevin
et al.
(2003) developed a model describing the process of pathogen control with time
under structural (dry) solarization. In an other study on modelling regular (wet) SH, the
common DH approach for predicting the rate of heat inactivation was further improved by
giving different weights to the different temperatures, thus refi ning the correlation
between temperature data and pathogen survival from
R
2
= 0.324 to
R
2
= 0.86 (Shlevin
et al.,
2005).
10.6.2
Decision-making tools
We should aim to control pests only when it is effective, and economically and
environmentally justifi ed, as required by the IPM approach. This can be achieved through
the use of decision-making tools (Katan, 1996; Davis
et al.,
2008). Such tools are used
for foliar diseases, but much less for soil-borne pathogens. They have the potential to
improve, control and reduce harmful effects on the environment. They can be especially
useful for solarization.
The necessary decision-making tools for the management of soil-borne pathogens by
solarization are:
(a)
Monitoring pathogen populations in the soil, for which sensitive assays are needed.
(b)
Studying relationships between inoculum density and disease incidence, as well as
between disease incidence and yield.
Predictive models for soil heating, which have already been developed, combined
(c)
with models on pathogen control under a solarization regime, as described above, are
potentially powerful tools for this purpose.
Economic considerations, especially regarding yield reduction by the pathogen
(d)
(Yaron
et al.,
1991).
Consideration of the level of soil suppressiveness, wherever possible.
(e)
10.7
Improvements by intensifying soil heating
Solarization is the simplest method to apply for soil disinfestation. Nevertheless, since
the day of its introduction, solarization has undergone continual improvement and
technological innovation in order to adapt the method to a wide variety of conditions and
cropping systems. Improvements are also needed to overcome diffi culties, limitations,
and existing negative attributes which have already been encountered or could potentially
occur. Advanced solarization seeks to achieve additional goals, such as improving the
level of control and creating a more long-term effect, lasting throughout a season or over
successive seasons. Some of the other reasons for improvements are cost reduction, and
increasing the reliability and reproducibility of the method, which is climate-dependent;
however, others include shortening the period during which the soil is occupied with
mulch, and making solarization possible for longer periods during the year and more
acceptable.
Improvement of SH can be achieved by either using improved plastic or modifying the
application technology. For example, by solarizing shallow layers of growth substrates,
