A Re-Appraisal of the Extraction of Heterodera Cysts From Large Volumes of Soil

Abstract

The labour of extracting cysts from large volumes of soil has been lessened by redesign of the flotation apparatus and automation of the process, where possible. The soil is dried and crushed with a hand roller on a concrete floor and poured into a hopper in the room below. A vibratory chute carries the soil to a water tank in which the soil particles sediment and the cysts and other debris flow onto a bank of sieves. Two models were tested, in the first the sediment was accumulated in the well of the tank and was periodically removed, in the second the sediment was continuously pumped into the drain where the water from the sieves washed it away. The coarse debris was removed on a 813 μ sieve and the cysts collected on a 230 μ sieve from which they were removed once or twice a day for drying and cleaning. In efficiency this method was equal to a Fenwick can used for 200 g of soil and better than a can used for larger samples.