Diagnosing root lesion nematode in cereals

Soil-borne pests infecting roots and reducing yield of cereals. Can only be properly diagnosed via a pathology test.

What to look for

Affected plants stunted and poorly tillered and can wilt despite moist soil.
Roots can have indistinct brown lesions or, more often, generalised root browning.
Badly affected roots are thin and poorly branched with fewer and shorter laterals.
Roots may appear withered with crown roots often less affected than primary roots.
Roots can assume a ‘noodle-like’ root thickening appearance.

Main root lesion nematode (RLN) species in WA are Pratylenchus neglectus and P. teres. they differ in their effect on individual crop and pasture types.
RLN over summer survive in a dehydrated form and move through moist soil attacking plant roots.
Once established they can be controlled but not eradicated.

Identification of the species of nematode is essential to choosing management options.
Root-lesion nematode can be managed with crop rotations but cannot be eradicated.
Wheat, barley and oats are susceptible to RLN but varieties differ in their degree of susceptibility.
Resistance of other crop and pasture species vary with nematode species.
Control susceptible weeds and susceptible crop volunteers to reduce RLN build-up and carryover.
Provide adequate nutrition to reduce the RLN impact on shoot growth and yield.
Avoid using root-pruning herbicides if possible.

Soil test

PreDicta B is a DNA-based soil testing service to identify the risk of cereal cyst nematode, take-all, rhizoctonia root rot, crown rot and root-lesion nematode (Pratylenchus neglectus and P. thornei) to broadacre crops before seeding.
This test does not identify P. teres (common in barley) and P. penetrans. AGWEST Plant Laboratories can do a complete identification during the growing season.