Agriculture Reference
In-Depth Information
(Davis, 1991; Davis et al ., 2008). The list of pathogenic fungi which are controlled
by solarization includes many key pathogens, such as Verticillium, Rhizoctonia and
Fusarium. The fi rst focus of solarization was aimed at controlling diseases caused by
pathogenic fungi, such as Verticillium wilt in eggplants and tomatoes (Katan et al., 1976),
Fusarium wilt in cotton (Katan et al., 1983) and Rhizoctonia in potatoes (Elad et al.,
1980). The wide spectrum of pathogen control was evident in the early days of solariza-
tion when combined control of both V. dahliae and Pratylenchus thornei was achieved in
potatoes, along with a 33% increase in yield and successful weed control (Grinstein et al.,
1979). Similar results regarding the control of Verticillium wilt were observed by Davis
& Sorensen (1986) in Idaho.
The heat-tolerant pathogens Monosporascus cannonballus and Macrophomina
phaseolina are not controlled by solarization. Fusarium oxysporum f. sp . dianthi is also
considered one of the wilt pathogens that is not easily controlled by solarization (Tjamos
et al., 1999).
The control of phytopathogenic bacteria by solarization has only been reported in a
relatively few cases. Soil-borne bacteria, including Agrobacterium and Streptomyces ,
are among the bacteria controlled by solarization. Streptomyces scabies is an important
pathogen of potatoes and peanuts, which has also been reported to respond to solariza-
tion (Davis & Sorensen, 1986; Grinstein et al., 1995). Solarization for 8 weeks in tomato
plastic houses drastically reduced symptoms caused by Clavibacter michiganensis ssp.
michiganensis (Antoniou et al., 1995). Solarization reduced populations of Gram-positive
bacteria by 64-99% (Stapleton & Garza-Lopez, 1988). It has been shown in a detailed
study in Oregon that Agrobacterium spp. population densities declined within solarized
plots and incidence of crown gall on cherry root stock planted in solarized soil was
reduced signifi cantly (Pinkerton et al ., 2000). Negative effects, due to control of benefi cial
rhizobia, have also been reported (Abdel-Rahim et al., 1988).
Many phytopathogenic nematodes are controlled by solarization (Stapleton &
Heald, 1991). Reports of effective control of nematodes for a short time, such as in
annual crops, are well established. The effi cacy of solarization for long-term suppres-
sion of nematodes, such as in perennial crops, is inconclusive. Certain nematodes, such
as the root knot Meloidogyne sp., are not always effectively controlled by solariza-
tion. However, ectoparasite nematodes such as Pratylenchus and Ditylenchus are well
controlled (Grinstein et al., 1979; Siti et al., 1982). Many phytopathogenic nematodes
cannot survive at temperatures above 40 o C, and solarization therefore kills them in the
upper soil layers, but not necessarily at depths below 40 cm. One of the most impor-
tant, and as-yet unexplored, factors in nematode suppression is their upward migration
from the deep soil layers to the root zone following plant establishment during crop
growth. This effect might be connected with failure of nematode control by SH and other
disinfestation methods.
Solarization has been found to be effective in reducing the viability of various weeds.
The spectrum of controlled weeds includes species of winter and summer annual weeds
(Elmore, 1991; Cohen & Rubin, 2007). A parasitic weed of the genus Orobanchae was
controlled by solarization, (Jacobsohn et al., 1980; Abdel Rahim et al., 1988). Similar
results were obtained in the laboratory with the parasitic weed Striga (Elmore, 1991). In
contrast, differential responses are achieved with solarization in perennial weeds. Weeds
from the genus Cyperus are inconsistently controlled by solarization (Elmore, 1991).
Search WWH ::




Custom Search