INVESTIGATIONS ON RESISTANCE OF OATS TO STEM EELWORM, DITYLENCHUS DIPSACI KÜHN

A procedure adopted for testing many varieties of oats and segregating progenies for reaction to attack by stem eelworm ( Ditylenchus dipsaci Kühn) is described, and its merits and limitations discussed in relation to the breeding of resistant varieties.
A study of some 250 forms of oats revealed new sources of resistance in cultivated and wild species. New sources of resistance in the cultivated species Avena sativa were found only in winter types, and in the other hexaploid species in forms belonging to A. byzantina (C) Koch, and the winter wild oat A. ludoviciana Dur.
Segregate progenies in advanced generations could be selected in the field by their reaction in a single drill in the first year followed by a head-row progeny test in the next season. Reaction was sufficiently well defined to identify the truebreeding resistant and susceptible lines.
The inheritance of reaction to stem eelworm in crosses involving Grey Winter and susceptible types depended on a single factor pair with resistance dominant.