Cinmethylin, a pre-emergence herbicide inhibiting fatty acid thioesterase activity, has recently been introduced to Australian cereal cropping for the control of Lolium rigidum Gaud. (annual ryegrass). To date, there have been no confirmed cases of cinmethylin resistance identified in this species, but some populations exhibit reduced sensitivity to this herbicide.
This paper reviews the reproductive biology, herbicide-resistant biotypes, pollen-mediated gene flow (PMGF), and potential for transfer of alleles from herbicide-resistant to herbicide-susceptible grass weeds including barnyard grass, creeping bentgrass, Italian ryegrass, Johnson grass, rigid (annual) ryegrass, and wild oats.
Lolium rigidum is the most important weed in Australian agriculture and the pre-emergence dinitroaniline herbicides (e.g. trifluralin) are widely and persistently used for Lolium control. Consequently, resistance evolution to dinitroaniline herbicides has been increasingly reported. Resistance-endowing target-site 𝛼-tubulin gene mutations are identified with varying frequencies. The present study investigated the putative fitness cost associated with the common resistance mutation Val-202-Phe, and the rare resistance mutation of Arg-243-Met causing helical plant growth.
Lolium rigidum (annual ryegrass) is a species that is prone to evolve resistance to a wide range of herbicide modes of action. Rapid detection of herbicide-resistant weed populations in the field can aid farmers to optimize the use of effective herbicides for their control.
The herbicide pyroxasulfone was widely introduced in 2012, and cases of evolved resistance in weeds such as annual ryegrass (Lolium rigidum Gaud.) and tall waterhemp [Amaranthus tuberculatus (Moq.) Sauer] have started to emerge.
This study provides evidence that trait(s) enabling efficient trifluralin metabolism in Lolium rigidum are purged from the population under prosulfocarb recurrent selection.
It is speculated that survival to prosulfocarb via a lack of metabolic herbicide activation, and survival to trifluralin conferred by enhanced herbicide metabolism, are mutually exclusive.
Most Australian crop farm populations of the grass weed Lolium rigidum are multiple herbicide-resistant. Most resistant populations exhibit target site mutations (e.g. ACCase, ALS), as well as metabolic resistance due to cytochrome P450, catalysed by enhanced rates of herbicide metabolism.
Light is an important resource that crops and weeds compete for and so increased light interception by the crop can be used as a method of weed suppression in cereal crops. This research investigated the impact of altered availability of photosynthetically active radiation (PAR) (from crop row orientation or seeding rate) on the growth and fecundity of Lolium rigidum.
Transgenic glyphosate-resistant canola was first commercially grown in Western Australia (WA) in 2010, providing an opportunity to obtain important baseline data regarding the level of glyphosate resistance in weeds following the exclusive use of glyphosate for in-crop weed control. In this study, two surveys (2010 and 2011) were conducted across the 14 Mha of the grainbelt of WA.
α-Amylase in grass caryopses (seeds) is usually expressed upon commencement of germination and is rarely seen in dry, mature seeds. A heat-stable α-amylase activity was unexpectedly selected for expression in dry annual ryegrass (Lolium rigidum) seeds during targeted selection for low primary dormancy.