Alternative Options to Glyphosate for Control of Large and Plants in Cropping Fallows.

The over-reliance on the herbicide glyphosate for knockdown weed control in fallows under minimum and zero-till cropping systems has led to an increase in populations of glyphosate-resistant weeds. and are two major grass weeds in the cropping regions of northern New South Wales and southern Queensland, Australia, that have become harder to kill due to a steady rise in the occurrence of glyphosate-resistant weed populations. Therefore, to help growers contain these hard to kill fallow weeds, an alternate approach to glyphosate application is needed. With this purpose in mind, a pot study was carried out during the summer seasons of 2015 and 2016 at the Tamworth Agricultural Institute, Tamworth, NSW, Australia, to evaluate the efficacy of tank mixtures and sequential applications of Group H (4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor), Group C (inhibitors of photosynthesis at photosystem II), Group A (ACCase inhibitors) and Group L (photosystem I inhibitor) herbicides on late tillering and plants. These herbicide groups are a global classification by the Herbicide Resistance Action Committee. Highly effective results were achieved in this study using combinations of Groups H, C, A and L herbicides applied as tank mixtures for controlling large plants. Additionally, sequential applications of Group H, C and A herbicides followed by (fb) paraquat were shown to be very effective on large plants. Late tillering plants were generally well controlled by tank mixtures, and sequential applications proved to be highly effective on this grass weed as well. Haloxyfop in combination with paraquat as a tank mixture, via sequential application or as a stand-alone treatment, was highly effective for control; however, using combinations of herbicide groups is the preferred choice when combating herbicide resistant weed populations. There was a clear synergy shown using Group H, Group C and Group A herbicides in combination with the Group L herbicide paraquat in this study for controlling advanced and plants. These combinations were shown to be successful on plants grown under glasshouse conditions; however; these treatments would need to be tested on plants grown in a field situation to show whether they will be a useful solution for farmers who are trying to control these weeds in fallow.