Distinguishing the species - CIMMYT

Seed gall nematodes (Anguina tritici) were
among the first to be recognized as a cause of
disease in wheat. This parasite also infests rye,
triticale and related species. Seed gall occurs on
wheat chiefly in the northern part of the Eastern
Hemisphere, particularly throughout the Near and
Middle East. The symptoms appear before heading
as distorted leaves and lower stems. As the plants
approach matu rity, ga lis are formed in the florets
and replace the seed. The galls are similar in size to
the seed they replace, dark brown in color, and
Figure 257. A comparison of seed galls (cockles), caused by
the nematode Anguina tritici (left)' with normal wheat seed
(right).
Figure 258. Seed galls are filled with dormant nematodes
(A. tritie;), which become active in moisture.
124
more difficult to crush than bunt balls (Figure
257). Large numbers of motile nematode larvae
are contained in the seed galls (Figure 258) and
become active after the galls have been moistened.
The seed galls, when mixed with seed to be planted,
provide a means of propagation.
Oat cyst nematodes (Heterodera avenae)
are widespread in the cereal-growing areas of the
world. Wheat, oats and rye are susceptible. The
roots of infested plants develop frequent branches
and swellings (knots). Cysts can be observed
clinging to the roots (Figure 259). The cysts are
light grey when young and dark brown when old.
The female of H. avenae has a characteristic saclike
body containing large numbers of eggs that remain
in the sac even after her death.
\
Figure 259. Wheat roots infested with
oat cyst nematodes. Note the cysts
clinging to the roots.