Cereal cyst nematode of wheat

Description:
Cereal Cyst Nematode (CCN) is a soil nematode causing yellowing or paling of young cereal crops and significant yield losses in some situations. On heavy fertile soils crops tend to lighter green in affected areas whereas on sandy soils the crops tend to be yellow. At early tillering affected plants are pale, slightly stunted with erect and duller leaves and reduced tillering. It often occurs in irregular shaped patches from 1 metre to 100 m in diameter. The roots tend to be tangled into a ball with the roots shortened and thickened and knotted with 1 to many, round, circular, tiny, initially white cysts at some of the knots. The cysts turn brown with age. Root symptoms tend to be seen on the seminal roots (arising from the seed) and sometimes later on the tiller or crown roots. Crops tend to apparently recover in spring when the more crown roots form. On Oat the typical "knots" may not form and the root system may be shallow with missing lateral roots and root hairs.
Each cyst contains hundreds of tiny, oblong, bullet like eggs and egg has a tiny juvenile nematode curled up inside which can only be seen under a microscope.
At 11-13 weeks after germination, female nematodes may be seen at the "knots" or thickened sections of the root.

Species Affected:
Spear, Halberd and Durum Wheat and Echidna Oats are significantly damaged by CCN.
Wild Oats are susceptible.
Barley, Cereal Rye and Triticale are tolerant and yield well despite being attacked.
Frame Wheat, Galleon and Sloop Barley, Wallaroo and Marloo Oats are resistant to CCN and stop it producing eggs.
Barley Grass, Brome Grass and Ryegrass are resistant and reduce soil populations of CCN.
Broad-leaved plants are tolerant.