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
- Crops appear patchy with uneven growth, and may appear nutrient deficient.
- Double sown and more fertile areas are often less affected.
Paddock
- 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.
Plant
What else could it be
| Condition | Similarities | Differences |
|---|---|---|
| Diagnosing rhizoctonia root rot in cereals | Patches of stunted plants | Rhizoctonia root rot patches are more distinct with spear tip roots. |
|
Trifluralin and no-till sowing with tynes
|
Cause 'sphaghetti root' symptoms | However symptoms are worse on shallower sown plants in more sandy low organic matter soils, and seriously damaged plants have very stubby thickened roots. |
|
Nutrient deficiencies
|
Pale plants | Root lesion nematodes cause the characteristic 'spaghetti roots'. |
Where did it come from?
- 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.
Management strategies
- 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.
How can it be monitored?
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.
See also
Further information
Where to go for expert help
Page last updated: Tuesday, 6 September 2016 - 9:37am