Weed Ecology & Management

Weed populations are dynamic in nature and can change rapidly in response to different management practices such as herbicide application and tillage systems. It is important to understand the underlying mechanisms that enable different weed species to adapt to different selection pressures. Weed Ecology & Management research group is led by Assoc. Assoc. Professor Gurjeet Gill.

Research Projects

Tillage systems effects on weed ecology & herbicide activity

Tillage systems can have a dramatic effect on soil throw and vertical distribution of weed seeds which in turn affects seed germination and establishment of weeds. Depending on the weed species, the response to seed burial can vary from strong inhibition to strong stimulation germination and seedling recruitment. The type of response is often species specific and related to light interactions with seeds and capacity to emerge from depth (ie. available energy). This has been an extremely productive area of research which has resulted in many publications in international journals. This research has been funded by GRDC and John Allwright Fellowships from ACIAR.

Researchers: A/Prof Gurjeet Gill, Bhagirath Chauhan (PhD project), Samuel Kleemann

Development of weed competitive wheat cultivars

As compared to other cereals, wheat is a poor competitor with weeds. Wheat is also the most widely grown cereal crop in southern Australia where herbicide resistance in weeds is still increasing at an alarming rate. Therefore, it is vital that research is undertaken to improve weed competitive ability of wheat. . In an alternative approach to boost early vigour and weed competitive ability, selected DH lines were taken through four cycles of recurrent selection that resulted in an average gain of 6% in early leaf area per cycle. These elite high vigour lines have since been crossed to donors of gibberellic acid sensitive dwarfing genes (Rht8, Rht12 and Rht13) and top-crossed to selected cultivars. This is the only project in Australia where breeding focus is solely on weed competitive ability of wheat. The project is funded by GRDC.

Collaborators: Dr Greg Rebetzke (CSIRO, Plant Industry, Canberra)

Researchers: A/Prof Gurjeet Gill, Michael Zerner

Herbicide resistance in weed species

Herbicide resistance is a major problem facing grain growers across the winter cropping region and is an emerging problem in summer cropping, horticulture and other systems in Australia. At its worst, herbicide resistance can seriously constrain cropping by forcing growers to adopt less profitable alternatives such as pastures, hay or even green manure crops. Resistance to group A and B in annual ryegrass became widespread in 1990s but growers were able to switch to trifluralin to maintain weed control. Now there are clear signs from surveys that resistance to this herbicide is also increasing at an alarming rate.

Collaborators: Dr Christopher Preston (UA), Dr Peter Boutsalis (UA), Peter Hooper (Mayfield Consulting, Clare)

Researchers: A/Prof Gurjeet Gill, Benjamin Fleet (PhD project)

Other research themes currently being pursued by this group include:

• Identification of genetic sources of tolerance to herbicides in wheat
• Degradation of imidazolinone herbicides in soils of South Australia
• Biology and ecology of Australian weeds
• Weed management issues under rapidly changing agricultural systems in developing countries

For information about studying in this field please visit our Student Services page.