Alternatives for soil fumigation in combating apple replant disease

Treatments aimed to absorb harmful compounds excreted by the microorganisims responsible for the replant disease were tested. According to Kummeler (1981), ethylene is such a compound. The ethylene content in the soil and root atmosphere of replanted apple plants was reduced by adding activated charcoal to the soil or by soil fumigation. Activated charcoal, compost or earthworm humus added to the soil placed in planting holes of replanted apples increased growth rates considerably. Another approach was the addition of mono-ammonium phosphate to replanted trees. This treatment was effective in soils treated with methyl bromide, due to the almost full elimination of VAM infection in such soils. In certain cases, however, this treatment was also highly effective in non fumigated soils.