Heterodera spp.
H. avenae
H. fillipjevi
H. latipons
H. hordecalis
H. zeae
H. mani
H. bifenestra
H. pakistanensis
- Symptoms: Cereal cyst nematodes are more readily detected on the roots of seedlings than on adult plants. The roots of infested plants develop frequent branches (picture at left) and swellings (cysts). The adult females, which are the size of a pinhead, are colored off-white when young, turning into dark brown cysts as they age (picture in middle). Seedlings weakened by nematodes often are invaded by soil-borne pathogens, especially root and crown rots. Below-ground symptoms include increased root production such that roots have a “bushy knotted” appearance, typically with several females visible at each root. Above-ground symptoms appear early in the season as pale green patches, with lower leaves of the plant being yellow, and a reduction in tillers (picture at right).
- Development: Larvae in moist soil penetrate roots near the growing point and grow into adults. Cell enlargement, root swelling, and root branching occur as the nematodes mature. Cysts are formed as the nematodes continue to develop into egg-producing adults.
- Hosts/Distribution: Yield loss has been documented on cereals in Europe, north-western India, southern Australia, Pakistan, Saudi Arabia, and the Pacific Northwest of the USA, but documented distribution has occurred in many more countries throughout the world. The host range of the group includes a wide range of both cultivated cereals and weed species. Leguminous plants are non-hosts, and offer a good rotation option for control.
- Importance: Many global reports have documented the economic importance of H. avenae, especially in rainfed cereal monocultures. H. filipjevi is very likely to be economically important to cereals because of its widespread distribution (including Russia, Tadzhikistan, Iran, Turkey, India, and Sweden), and the yield loss documented in Turkey
References:
- Dr. Julie M. Nicol- CIMMYT Soil Pathologist, Ankara, Turkey.
- Dr. Roger Rivoal- Senior Nematologist (retired), INRA, Le Rhue, Renne, France.