Which weeds host Pratylenchus by Denys Slee

BEWARE seasonal carryover of root lesion nematodes. University of Adelaide researchers Vivien Vanstone and Michelle Russ have shown that some annual and broad-leaf weeds can host nematodes and therefore may allow population build-up or carryover from season to season.

Dr Vanstone says the finding could mean that the full benefits of growing resistant crops to control nematodes are not achieved. "Differences between the two Pratylenchus species in weed susceptibility further emphasise the need for growers to identify which nematode species is present when making management decisions," she said.

The following table produced by Dr Vanstone and Ms Russ gives a good overview of the Pratylenchus host status of weed species.

Weed SpeciesP. neglectusP. thornei
Broad-leaf weeds
Skeleton weedNONNON
DandelionNONNON
Evening primroseNONNON
Short-fruited turnipNONNON
Ox tongueNONNON
BiforaNONNON
Sand rocketNONNON
BedstrawNONNON
Indian hedge mustardNONNON
Lincoln weedNONNON
Prickly lettuceNONNON
CapeweedNONNON
HeliotropeNONPOOR
Ward's weedPOORNON
MarshmallowPOORNON
Curled dockPOORNON
Three-cornered jackPOORNON
Long-fruited turnipPOORNON
CaltropPOORNON
Wild radishGOODNON
Narrow-leaf weeds
Onion weedNONNON
Barley grassNONGOOD
Brame grassPOORPOOR
Silver grassPOORNON
RyegrassNONNON
Wild oatVERY GOODPOOR

non-host = resistant (nematodes do not multiply)

poor host = slight build-up of nematode numbers

good host = susceptible (nematodes multiply)

Compared to Machete wheat (susceptible) and Abacus triticale (resistant)

Dr Vanstone said Pratylenchus research was continuing at the University of Adelaide with emphasis on assessing the P. neglectus resistance of new lines from Dr Tony Rathjen's wheat breeding program. She said some of this material looked very promising.

Break crops reminder

Crops including field peas, lentils, medic and durum wheat are rated resistant to the root lesion nematode Pratylenehus thornei, while peas, lentils and faba beans are resistant to P. neglectus.

Some wheat and barley varieties have moderate resistance to these pests while canol a varieties are rated as moderately susceptible or susceptible to P. neglectus, but moderately resistant to P. thornei.

Program 2.6.2 Contact: Dr Vivien Vanstone 08 8303 7456