Emerging weeds in the line of researchers' fire
Reducing control costs, delivering information that can help to develop management strategies, and slowing the rate of spread of weeds.
These are some of the aims of ‘emerging weeds’ research underway in Western Australia as part of national Grains Research and Development Corporation (GRDC) projects overseen by the University of Adelaide.
In WA, Northam-based Department of Agriculture and Food (DAFWA) researcher Abul Hashem is leading work under the projects ‘Seed bank biology of emerging weeds’ and ‘Improving integrated weed management (IWM) practice of emerging weeds in the southern and western regions’.
Following unseasonal rains in recent weeks, Dr Hashem has been contacted by a number of growers and grower groups seeking information about summer weed control.
According to Dr Hashem, changes in farming systems, farm management practices and climate are resulting in a changing weed spectrum.
In particular, summer weed species that are glyphosate tolerant are causing problems, including button grass, fleabane, tar vine, windmill grass, sowthistle and caltrop.
In addition, broad spectrum herbicide resistance is developing in several summer and winter weed species, increasing costs to growers and reducing yields.
As part of the ‘seed bank biology' project, 10 emerging WA weeds are being investigated: afghan melon, barley grass, brome grass, button grass, caltrop, doublegee, roly-poly, sowthistle, windmill grass and wireweed.
The list of weeds was decided in consultation with the GRDC’s Regional Cropping Networks (RCSNs), western regional panel and crop protection managers.
To manage these emerging weeds effectively, growers are seeking information about their behaviour - especially seed bank persistence, seed bank build-up and competitive effects on crops.
Currently, weed seed biology information is not available for many of them, as most previous research was conducted before the intensification of cropping and introduction of no-till systems in recent decades.
Dr Hashem and his team are collecting seed of the 10 weeds and conducting experiments to study seed dormancy, seed dispersal, seed bank persistence, seed production potential, and competitiveness with crops.
The associated IWM project aims to deliver growers new knowledge and tools including emergence pattern, cultural and chemical control, and crop competitiveness approaches for cost effective control of emerging weeds.
Under this IWM project, a weed survey was conducted by the DAFWA research team in 2015 to record the extent of emerging summer weeds along roadsides across the WA grainbelt.
Seed of selected weed species such as button grass, fleabane, sowthistle and tar vine was collected during this survey to test for resistance against glyphosate.
As well as surveys, the IWM project includes laboratory, glasshouse and field experiments to better understand weed biology, and small plot research to develop and demonstrate emergence patterns and appropriate control tactics.
Results from this survey and other information from the emerging weeds projects will be presented at the GRDC WA Grains Research Updates to be held in Perth from February 29 to March 1, 2016.
Useful resources for growers seeking information on summer weed control include the GRDC Pre-Harvest Herbicide Use Fact Sheet and the Summer Fallow Weed Management manual.
Information about weed control is also available at the GRDC Integrated Weed Management Hub and the WeedSmart website.
Abul Hashem, DAFWA
08 9690 2136, 0427 425 349
Chris Wilkins, GRDC western panellist
0427 940 925
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827
GRDC Project Code UA00149, UA00156