Crop rotation is the key to reducing nematode levels and the damage they cause according to Western Australia Department of Agriculture researcher Vivien Vanstone.

Dr Vanstone, who is speaking at the Northam Crop Updates on Thursday 24 February, warned growers that intensive cereal cropping was likely to lead to a build up of root lesion nematodes (RLN).

She said wheat, canola and chickpea crops were susceptible, while oat and barley were moderately susceptible.

RLN levels were assessed in a range of Department Crop Variety Testing and pulse trials over the 2003 and 2004 cropping seasons.   The research was supported by the Grains Research and Development Corporation.

“Field pea, faba bean and most lupin cultivars are resistant to Pratylenchus neglectus - the predominant species of root lesion nematode, which occurs in at least 60 per cent of  WA cropping paddocks,” Dr Vanstone said.

“These crops will effectively reduce levels of P. neglectus when used in rotations where this nematode has been identified at moderate to high levels.

“Although not resistant to P. neglectus, there is useful variation in susceptibility between cereal cultivars that can be exploited to manage nematode levels.  For example, Gairdner, Barque and Wyalkatchem will lead to lower nematode levels relative to the most susceptible cultivars such as Hamelin, Brookton, Machete, Carnamah and Westonia.”

Dr Vanstone said unlike the root lesion nematode, cereal cyst nematode (CCN) only infected cereals and other grasses.

“In 2004, CCN was detected in the Northern and Central Agricultural regions including the York and Northam areas.  In some cases these nematodes have reached high population levels,” she said.

“Where it is present, CCN will increase under intensive cereal cropping and growers are advised to avoid susceptible cereals and control grasses.  This nematode is readily managed through rotations incorporating resistant or non-cereal crops.”

Dr Vanstone said different nematode species had different host preferences so, to be effective, rotations needed to be tailored to the predominant nematode present.

She said correct diagnosis was important when devising rotational strategies for management of nematodes.  AGWEST Plant laboratories can conduct in-season nematode diagnosis.

In collaboration with colleagues at the SA Research and Development Institute (SARDI) and CSIRO Canberra, the Department of Agriculture is also assisting in the development and validation of additional diagnostic probes for the PreDicta-B™ test.

This will not only aid the Department’s research but ensure that the diversity of nematodes relevant to WA cropping systems will be more reliably detected in the future.

For further information about the Northam Crop Updates contact the Northam office of the Department of Agriculture on 9690 2000.