INVENTORY OF CYST NEMATODE 
tHeterodera schachtii Schm.) I NF ES TATIONS 
OF SUGAR BEETS BY APRRIAL I NPRA-~- 
RED PHOTOGRAPHY 
E. Sanwald, Abeilung Luftbildmessung und -interpretation, 
Universität Freiburg, Germany 
A b Ss tract 
Sugar beet fields can precisely be classified from aerial 
infrared colour photographs (scale: » 1 : 10.000). Visual, 
microdensitometric, and densitometric evaluations gave 
distinct separations between healthy and nematode diseased 
parts of sugar beet canopies. By visual interpretation, 
discrimination from other kinds of stresses is possible 
because of the typical patterns of nematode distribution 
in the fields. Field studies, and laboratory spectropho- 
tometric measurements of leaves, petioles, and soil com- 
plete the results. Thereby, this method has been proven to 
be more accurate and more economic than conventional soil 
probing methods, which were also applied during the course 
of these studies. It is presently being accepted for 
large-scale practical use in West Germany. 
Introduction 
The sugar beet cyst nematode Heterodera scha- 
chtii Schmidt is an animal belonging to the genus 
Nematod a, or thread worms. It is less than 1 mm in size, 
and lives in the soil, feeding on the rootlets of plants, part- 
icularly of such ones that belong to the Cruciferae and Cheno- 
podiaceae families. Therefore, in sugar beet fields its table is 
readily laid. In springtime, the larvae enter the roots of the 
young plants, and by means of their enzymes induce the formation 
of giant cells, the cytoplasm of which they use for nourishment. 
The life cycle of H. schachtii is completed in 4 to 6 
weeks’time, including 3 moltings to the fourth and final stage,