Managing the risk of glyphosate resistance in Australian glyphosate-resistant cotton production systems

BACKGROUND: Glyphosate-resistant cotton varieties are an important tool for weed control in Australian cotton production systems. To increase the sustainability of this technology and to minimise the likelihood of resistance evolving through its use, weed scientists, together with herbicide regulators, industry representatives and the technology owners, have developed a framework that guides the use of the technology. Central to this framework is a crop management plan (CMP) and grower accreditation course. A simulation model that takes into account the characteristics of the weed species, initial gene frequencies and any associated fitness penalties was developed to ensure that the CMP was sufficiently robust to minimise resistance risks. RESULTS: The simulations showed that, when a combination of weed control options was employed in addition to glyphosate, resistance did not evolve over the 30 year period of the simulation. CONCLUSION: These simulations underline the importance of maintaining an integrated system for weed management to prevent the evolution of glyphosate resistance, prolonging the use of glyphosate-resistant cotton.

Prospects for the biological control of the weedy sporobolus grasses in Australia.

Bill Palmer and colleagues recently published their paper 'Prospects for the biological control of the weedy sporobolus grasses in Australia' in Proceedings of the 16th Australian Weeds Conference. The paper gives a summary of a recent project to find a biological control for the weedy sporobolus grasses, which include giant rat's tail grass. Southern Africa was surveyed for potential agents and two, a leaf smut and a stem wasp, were selected for follow up studies. Unfortunately, they could not rear the stem wasp in the laboratory and the leaf smut infected four of the Australian native Sporobolus spp. and was therefore rejected. This project was one of the first attempts at biological control of a grass.

Ecological impacts of feral pig diggings in north Queensland rainforests

This two-year study examined the impacts of feral pig diggings on five ecological indicators: seedling survival, surface litter, subsurface plant biomass, earthworm biomass and soil moisture content. Twelve recovery exclosures were established in two habitats (characterised by wet and dry soil moisture) by fencing off areas of previous pig diggings. A total of 0.59 ha was excluded from further pig diggings and compared with 1.18 ha of unfenced control areas. Overall, seedling numbers increased 7% within the protected exclosures and decreased 37% within the unprotected controls over the two-year study period. A significant temporal interaction was found in the dry habitat, with seedling survival increasing with increasing time of protection from diggings. Feral pig diggings had no significant effect on surface litter biomass, subsurface plant biomass, earthworm biomass or soil moisture content.

Karyological Characteristics of Lilium ledebourii Boiss and Lilium longiflorum Thunb.

The karyological characteristics of two Lilium species were investigated by aceto-ferric-hematoxylin staining. Chromosome characteristics, including the number and length of the chromosomes, length of their long and short arms, length of the total set of chromosomes, the arm ratio index and relative lengths of chromosome, were measured based on averages for five different metaphase cells. Both species are diploid (2n=2x=24). The karyotype of Lilium ledebourii consisted of 1 pair of metacentric, 4 pairs of submetacentric, 3 pairs of acrocentric and 4 pairs of subtelocentric chromosomes. The karyotype of Lilium longiflorum was comprised of 1 pair of metacentric, 4 pairs of acrocentric and 7 pairs of subtelocentric chromosomes. Chromosomes 5 and 7 in Lilium ledebourii and chromosomes 6 in Lilium longiflorum had a satellite. Karyotypes were classified as 3A by Stebbins classification.