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

Dr Vanstone, who is speaking at the Geraldton Crop Updates on Monday 14 March, 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 Western Australia's 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.  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.

For further information about the Geraldton Crop Updates contact the Geraldton office of the Department of Agriculture, Western Australia on 9956 8555.