Soil solarization, a nonchemical technique to control many soil borne pathogens and pests. This simple technique captures radiant heat energy from the sun, thereby causing physical, chemical, and biological changes in the soil. Transparent polyethylene plastic placed on moist soil during the hot summer months increases soil temperatures to levels lethal to many soil borne plant pathogens, weed seeds, and seedlings (including parasitic seed plants), nematodes, and some soil residing mites. Soil solarization also improves plant nutrition by increasing the availability of nitrogen and other essential nutrients.
Benefits of Soil Solarization
Disease control:
Soil solarization has provided excellent control of several diseases in California and Israel, and for some gases, control has continued for at least two growing seasons.
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Preliminary evidence suggests that some pathogens may reinfest solarized soil at slower rates than nontreated soil.
Weed control:
Seed and seedlings of many annual and perennial weeds have been controlled with soil solarization. Some weed species are very sensitive to solarization. Others are moderately resistant and require for control optimum soil moisture, tight-fitting plastic close to the soil surface, and high radiation. Increased plant growth response. Plants often grow faster and produce yields of increased quantity and quality (size and appearance) when grown in solarized compared to nontreated soil.
Special Uses for Soil Solarization:
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Soil solarization has been used successfully on a large scale to control Verticillium wilt in pistachio orchards in California. Using both hand labor and plastic-laying machinery, the orchard floor was completely covered in plastic. Plastic strips were hand applied around tree bases and connected to a strip of machine- applied plastic between the tree rows with heat- resistant glue or by using narrow bands of earth to hold the strips down.
The 5 to 10-year-old trees partially shaded the soil and plastic but not enough to prevent soil heating, which the trees survived with no visible detrimental effects. Although expensive, success of this method in existing orchards indicates the high potential of solarization to control some soilborne problems.
Soil solarization has also been used successfully in Israel to control soilborne pests in greenhouses.
Soil solarization can control many soilborne pathogens and pests. The method is simple, safe, and effective, leaves no toxic residues, and can be easily used on a small or large scale. Large increases in plant growth, harvestable yield, and crop quality often occur in solarized soil and often continue for more than one growing season. The potential uses of soil solarization for disease and pest control in California are great.