When a new pest has such longevity that it becomes an archaeological artefact, you know you are up against a hearty foe.

When that foe possesses natural resistance to Western Australia’s most popular herbicide, glyphosate, it’s time to look for new answers.

That is exactly what the Grains Research & Development Corporation (GRDC) did when it supported a University of Western Australia (UWA) research team to investigate Malva parviflora (small flowered mallow) under the leadership of Associate Professor Julie Plummer.

Although fairly new to Western Australia, M.parviflora, fuelled by rapid seed maturation, has built up its numbers swiftly in recent years. While new generations can emerge quickly, coat-imposed dormancy means seeds can also persist in the seed bank, with viable seeds once found in 200 year old bricks in New Mexico (USA).

The pest pedigree of Malva species is underlined by M.pusilla, which doubled its population over five years during the 1980s in Canada, dragging down wheat yields by 30 per cent at the same time. Control of local species is therefore an obvious priority.

Those control strategies must be informed by biological and ecological understanding, which is the thesis topic for UWA PhD student, Pippa Michael, who will be supported by growers and the Federal Government through the GRDC.

To begin this process, M.parviflora seed was collected from 11 different crop variety testing zones early in 2002 and grown in trials at UWA’s Shenton Park field station, where population differences in flowering time, growth habit, height and weight were observed.

The pest displayed significant differences, despite belonging to the same species. For example, northern populations flower just 49 days after germination, while its southern counterparts take a further 43 days. Meanwhile, growth habit also varied, with Mingenew populations growing erect and those from Katanning prostrate, potentially making them more difficult to control.