Research interests

  • Herbicide damage
  • Weed botany
  • Weed and cotton physiology
  • Weed ecology
  • Weed science


Graham is an applied field scientist with over 27 years experience in aspects of weed management in the Australian cotton industry, covering such areas as the management of specific problem weeds, the effectiveness of the farming system, developing a threshold for weed control in cotton and the identification and management of herbicide damage in cotton.

He was the major author of “WEEDpak – the integrated weed management guide for cotton”, first released in 2002 and has added a huge amount of material to WEEDpak since its first release. WEEDpak if freely accessible on the internet, with its major sections being the Weed Identification Guide and the Herbicide damage Symptoms Guide.


  • B.Rur.Sc. University of New England, NSW (1983)
  • M.Rur.Sc University of New England, NSW (1990)

Current project

  • PhD study: Developing the weed control threshold

Recent publications

Werth J, Boucher, L, Thornby D, Walker S, Charles G (2014) Changes in weed species since the introduction of glyphosate-resistant cotton. Crop & Pasture Science, 64: 791-798.

Charles G.W. (2012). Weed management. In “NORpak – Burdekin and NQ coastal dry tropics cotton production and management guidelines.” p. 58 - 62.

Charles G.W. (2012). Herbicide damage. In “Cotton symptoms guide” p. 31-39.

Charles, G. (2012). Residual herbicides – a farming systems complication, Proceedings of the 16th Australian Cotton Conference, Broadbeach, 14-16 August 2011, p. 16-19.

Charles, G. and Thornby, D. (2012). Glyphosate resistance – an inconvenient truth, Proceedings of the 16th Australian Cotton Conference, Broadbeach, 14-16 August 2011, p. 20-22.

Thornby, D., Werth, J. and Charles, G. (2012). Weed management strategies for herbicide tolerant cotton. Proceedings of the 16th Australian Cotton Conference, Broadbeach, 14-16 August 2011, p. 81-84.

Charles G. (2011). Recovering from herbicide damage – induced water stress. The Australian Cottongrower 32 (4): 21-22.

Taylor, I., Werth, J. & Charles, G. Glyphosate resistance – coming to a field near you? The Australian Cottongrower 32 (6): 40-43.

Charles G. (2010). Residual herbicides – the hidden costs. The Australian Cottongrower 31 (6): 22-23.

Werth J, Thornby D, Walker SR, Charles G, McDonald C (2010) Species shift and resistance: challenges for Australian cotton systems. Proc 17th Australasian Weeds Conference. Christchurch, NZ. (Ed. SM Zydenbos) pp. 20-23. (New Zealand Plant Protection Society).

Charles, G. (2009). Its all phenoxy. The Australian Cottongrower 30 (7): 10-14.

Charles, G. (2009). Planning weed management decisions in cotton. The Australian Cottongrower 30 (7): 38-39.

Werth J.A., Preston C., Taylor I.N., Charles G.W., Roberts G.N. and Baker J. (2008) Managing the risk of glyphosate resistance in Australian glyphosate-resistant cotton production systems. Pest Management Science 64: 417-421.

Green T.D, Sindel B., Charles G. and Werth, J. (2008). A review of the ecology of fleabane (Conyza spp.). 16th Australian Weeds Conference, Cains, 171-173.

Fields of research

  • 070302 Agronomy
  • 070303 Crop and pasture biochemistry and physiology
  • 070308 Crop and pasture protection (pests, diseases and weeds)

Keyword/phrase list of research interests

  • Weed science
  • Cotton
  • Weed ecology