and mating. The enlarged abdomen of the fecundated female, the 
so-called cyst, remains in the soil. It contains 300 fertile eggs 
on an average, and by means of its hardened outer wall it can 
persist in the soil for years, releasing newly hatched larvae 
whenever conditions are favourable. Apart from that, during the 
same summer a second generation emerges from up to 200 eggs 
which are laid into a mucuous mass outside the vulval region. 
Under favourable conditions, even a third generation may complete 
its life cycle before harvest of the sugar beets (DECKER 1969). 
By the formation of the giant cells (syncytiae) in the root- 
lets, transport ways for water and nutrients are blocked. the 
root body remains small, and yield decreases heavily. During 
periods of warm and dry days in summertime, the water which is 
evaporated by the leaves cannot be replaced by the roots in 
sufficient amounts, and therefore the leaves begin to lose 
their turgor, and slack down. Because the nematode cannot move 
very far in the soil by itself, it is mostly spread passively, 
and so it occurs in patches in the field, which can be recognized 
by the infested, slackening plants being surrounded by non-infe- 
sted, turgid plants. Generally, the leaves keep their dark-green 
colour, and become turgid again for a short period after rain 
showers or irrigation. 
As can be understood from these brief biological explanations, 
the multiplication rate of those harmful organisms is an enormous 
one. Farmers and sugar companies alike suffer from steadily 
increasing economic losses. Countermeasures like planting sugar 
beets every three or four years only, and no other host plants, 
such as rapeseed, in between, have shown to be unsuccessful in 
bringing down the population rate below an economically bearable 
level. Only recently, the possibility of applying chemical soil 
fumigants effectively has been realized by the development of new 
technical application equipment.