Alarm bells are sounding, with increasing reports of nematode damage to wheat crops following rotation with lupins.

Lupins have been regarded as a resistant weapon able to knock back numbers of major root lesion nematode (RLN) species, such as Pratylenchus neglectus and P. thornei and clear the way for healthy production from subsequent cereal crops.

However in the late 1990s, with support from growers and the Federal Government through the Grains Research and Development Corporation (GRDC), Dr Ian Riley of the Department of Agriculture found ‘burrowing nematode’ (Radopholus nativus) damaging wheat crops for the first time. Many of those wheat crops followed lupin rotations, which raised suspicions that, unlike its notorious RLN cousins, the burrowing nematode enjoyed feasting on lupin roots.

The burrowing nematode has since been found across most of WA’s cropping zone. Its importance as a parasite and the range of susceptible crops required investigation.

The GRDC therefore supported a follow-on project, supervised by the Department’s Dr Vivien Vanstone, which will continue investigating members of WA’s diverse RLN population and addressing the burrowing nematode to identify control strategies.

It will focus on the general control of RLN in cereal/canola rotations and overcoming burrowing nematode in lupin/wheat rotations. Lupins are planted across more than one million WA hectares, making the control of the potentially damaging burrowing nematode a priority for the crop itself and for subsequent wheat crops.

The project will look at the affect of nutrition, weed management and crop and variety selection in diminishing soil RLN numbers.

Nitrogen, zinc and phosphorus applications have been shown, in previous GRDC supported research in SA, to increase crop resistance and tolerance to RLN. Meanwhile, soil RLN numbers can build under minimum or zero tillage regimes and so packages involving resistant cultivars must be developed and integrated into those systems.

But while rotations with resistant varieties are central to hopes of dropping RLN numbers, that control should not be compromised by the presence of susceptible weeds or volunteer cereals harbouring the pest for a fresh assault on subsequent crops.