Survey of weed flora and management relative to cropping practices in the north-eastern grain region of Australia

Abstract

The main weeds and weed management practices undertaken in broad acre dryland cropping areas of north-eastern Australia have been identified. The information was collected in a comprehensive postal survey of both growers and agronomists from Dubbo in New South Wales (NSW) through to Clermont in central Queensland, where 237 surveys were returned. A very diverse weed flora of 105 weeds from 91 genera was identified for the three cropping zones within the region (central Queensland, southern Queensland and northern NSW). Twenty-three weeds were common to all cropping zones. The major common weeds were Sonchus oleraceus, Rapistrum rugosum, Echinochloa spp. and Urochloa panicoides. The main weeds were identified for both summer and winter fallows, and sorghum, wheat and chickpea crops for each of the zones, with some commonality as well as floral uniqueness recorded. More genera were recorded in the fallows than in crops, and those in summer fallows exceeded the number in winter. Across the region, weed management relied heavily on herbicides. In fallows, glyphosate and mixes with glyphosate were very common, although the importance of the glyphosate mix partner differed among the cropping zones. Use and importance of pre-emergence herbicides in-crop varied considerably among the zones. In wheat, more graminicides were used in northern NSW than in southern Queensland, and virtually none were used in central Queensland, reflecting the differences in winter grass weed flora across the region. Atrazine was the major herbicide used in sorghum, although metolachlor was also used predominantly in northern NSW. Fallow and inter-row cultivation were used more often in the southern areas of the region. Grazing of fallows was more prominent in northern NSW. High crop seeding rates were not commonly recorded indicating that growers are not using crop competition as a tool for weed management. Although many management practices were recorded overall, few growers were using integrated weed management, and herbicide resistance has been and continues to be an issue for the region.

Target-site EPSPS Pro-106 mutations: sufficient to endow glyphosate resistance in polyploidEchinochloa colona?

“…Although not examined in our study or in other studies, reduced glyphosate efficacy at high temperatures may be due to increased glyphosate upward movement caused by higher rates of plant transpiration, thus decreasing glyphosate translocation. E. colona is the most common weed of summer fallows in the north‐eastern grain region of Australia; extreme growing conditions have been recorded, and higher temperatures (over 35 °C) in summer are quite common . In addition, other factors reducing glyphosate rates (e.g.…”

“…7 Echinochloa colona L. (Link), a tetraploid or hexaploid, 8,9 is a major annual grass weed species in summer crops and fallows in subtropical Australia. 10,11 Glyphosate has long been used for its control. Glyphosate-resistant E. colona was first confirmed in 2007 in northern New South Wales.…”

Control by glyphosate and its alternatives of glyphosate‐susceptible and glyphosate‐resistant Echinochloa colona in the fallow phase of crop rotations in subtropical Australia

“…With the introduction of reduced or zero‐tillage farming systems, weeds no longer have been controlled with tillage and thus the reliance on herbicides, particularly glyphosate, has increased (Osten et al . ).…”

“…Echinochloa colona L. (Link), known as awnless barnyard grass, is a widespread and major weed in summer crops and fallows in the subtropical region of north-eastern Australia (Osten et al 2007). In fields that were surveyed from 1997 to 2000, Echinochloa spp.…”

Epidemiology and genetic diversity of Tobacco streak virus and related subgroup 1 ilarviruses

“…C. bonariensis is a small seeded weed that is widely distributed across much of the cropping regions in north-east Australia and has greatly increased in prevalence over the last couple of decades (Walker and Robinson 2008). Many populations of this weed across this region have also developed significant resistance to glyphosate (Walker et al 2011), the dominant herbicide used for fallow weed control in minimum tillage farming systems across this region (Osten et al 2007). It appears quite feasible that the very small, TSV-infected seeds of this weed could be easily moved on machinery or livestock into new cropping regions.…”