Field peas are playing an important role in reducing damaging levels of soil nematodes in Western Australia's cereal crops. 

Vivien Vanstone, senior plant nematologist  at the Department of Agriculture, Western Australia, said field peas were resistant to Western Australia’s most prominent Root Lesion Nematode (RLN) species, Pratylenchus neglectus. 

Dr Vanstone said in suitable growing areas, field peas were one crop recommended for use in rotations where moderate to high levels of P. neglectus were identified. 

“Root lesion nematodes occur at damaging levels in at least 40 per cent of WA cropping paddocks,” Dr Vanstone said. 

“Cereals grown after field peas should have substantially lower levels of P. neglectus infection, resulting in less root damage and lower yield loss.” 

“When planning management strategies, it is important to determine not only the levels, but also the species of nematode present, as there are several in Western Australia that can damage crops.  Samples can be analysed by AGWEST Plant Laboratories.”

Dr Vanstone said rotation with resistant crops such as field peas was the best management option.  However, rotations needed to be tailored to combat the predominant species of nematode present. 

The resistance of field peas to P. neglectus was demonstrated in field trials during 2003.  P. neglectus did not multiply on any of the five field pea varieties tested at Muresk, Scaddan or Borden.  In fact, nematode levels decreased during the growing season.  

Although nematode levels were initially high at sowing (10 per gram of soil), growing field peas resulted in levels of less than one nematode per gram of soil by September.  These trials have been over-sown with wheat and barley varieties in 2004 to investigate changes in nematode levels following the resistant field peas.

Dr Vanstone said although field peas were resistant to P. neglectus, a trial sampled at Mt Barker in 2003 indicated they could be susceptible to another RLN species, P. penetrans.

Although P. penetrans is detected infrequently in cropping areas, field peas may be a less suitable break crop for this nematode.  This highlights the need to determine which RLN species is present so that appropriate rotations can be used for management.