13. Sterilisation
Soil fumigation or as an alternative, an integrated organic approach
(composts and friendly bacteria), is advisable and should occur prior to every
planting. This will help eliminate soil borne pathogens ‐ rhizoctonia, fusarium,
pythium, sclerotia rolfsii and pests such as nematodes and grass grub ‐ all can
cause major tuber losses.
Steam as a soil sterilant is now more commonly used, and is environmentally
safe. It kills most pathogens and weeds when correctly applied. Steam should
be applied at 80°C.
If employing chemicals, a mixture of 70% Methyl Bromide (MB) / 30%
Chloropicrin as an injected gas (500kg/ha) also gives effective pathogen
control as well as killing most weeds (not clover or mallow).
Alternatives (e.g. Basamid®) are used successfully but their efficacy is
dependent on application methods and the strength of active ingredient
relative to media or soil type.
Soil temperature should be above 10°C and just moist for successful
sterilization (to kill germinating weed seed). Penetration of gas is reduced in
dry or waterlogged conditions. 7 days after application, lift covers, and 7 days
later, cultivate soil to release residual gas. A minimum total aeration time of
21 days is recommended.
Use a ‘cress test’ if in doubt (germinate cress or radish seed in a sample of the
soil to check for gas ‐ if they germinate the soil is clear).
Methyl Bromide (now outlawed in many countries) on its own has limited
action against fungal pathogens, especially after repeated crops.
Other fumigants like Basamid® are used but efficacy depends on application
methods and the strength of active ingredient relative to different soil types.
13. SterilisationSoil fumigation or as an alternative, an integrated organic approach(composts and friendly bacteria), is advisable and should occur prior to everyplanting. This will help eliminate soil borne pathogens ‐ rhizoctonia, fusarium,pythium, sclerotia rolfsii and pests such as nematodes and grass grub ‐ all cancause major tuber losses.Steam as a soil sterilant is now more commonly used, and is environmentallysafe. It kills most pathogens and weeds when correctly applied. Steam shouldbe applied at 80°C.If employing chemicals, a mixture of 70% Methyl Bromide (MB) / 30%Chloropicrin as an injected gas (500kg/ha) also gives effective pathogencontrol as well as killing most weeds (not clover or mallow).Alternatives (e.g. Basamid®) are used successfully but their efficacy isdependent on application methods and the strength of active ingredientrelative to media or soil type.Soil temperature should be above 10°C and just moist for successfulsterilization (to kill germinating weed seed). Penetration of gas is reduced indry or waterlogged conditions. 7 days after application, lift covers, and 7 dayslater, cultivate soil to release residual gas. A minimum total aeration time of21 days is recommended.Use a ‘cress test’ if in doubt (germinate cress or radish seed in a sample of thesoil to check for gas ‐ if they germinate the soil is clear).Methyl Bromide (now outlawed in many countries) on its own has limitedดำเนินการกับโรคเชื้อรา โดยเฉพาะอย่างยิ่งหลังจากพืชซ้ำใช้ fumigants อื่น ๆ เช่น Basamid ® แต่ประสิทธิภาพขึ้นอยู่กับโปรแกรมประยุกต์วิธีการและความแข็งแรงของตัวยาสำคัญที่สัมพันธ์กับชนิดของดินที่แตกต่างกัน
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