Pyroxasulfone efficacy for annual ryegrass control is affected by wheat residue height, amount and orientation

Abstract

BACKGROUND Pre‐emergent herbicides play an important role in conservation agriculture, however, crop residues on the soil surface in these systems can intercept a considerable amount of herbicide during application. Cutting crops relatively high at harvest has some advantages, such as allowing faster harvest, and this also means that there is less horizontal residue on the soil surface. This field study tested the impact of standing wheat residue height and amount of horizontal residue on the interception, leaching and weed‐control efficacy of the pre‐emergent herbicide pyroxasulfone in the 2015 and 2016 growing seasons. RESULTS Spray coverage of pyroxasulfone declined from 14.6% to 7.5% with increasing amounts (0 to 4 t ha−1) of horizontal wheat residue. Horizontal wheat residue at 1 t ha−1 had 10.3% spray coverage (more herbicide interception) compared with 15.4% for the equivalent amount of standing residue. Greater amounts of horizontal residue also significantly reduced the efficacy of pyroxasulfone in controlling ryegrass in the field and decreased pyroxasulfone concentrations in the soil. Rainfall after herbicide application increased herbicide efficacy for all residue amounts. Generally, cutting standing residue higher resulted a relatively small decrease in spray coverage at the soil surface and weed control efficacy, and this was significant only between nil stubble and 0.3 m cut height. CONCLUSION Cutting residue relatively high, leaving less on the surface, improves spray coverage and herbicide efficacy compared with having more horizontal residue. This research may assist farmers and advisors to maximize the efficacy of pre‐emergent herbicide in no‐tillage systems. © 2019 Society of Chemical Industry

Pre-emergent herbicides: benefits and restrictions for rational use

“…In the same weed, pyroxasulfone did not present differences in control due to the presence of straw; the control was excellent with 6000 kg.ha -1 of oat stubble and even when the simulated rain was 14 days after the application. These results were contradictory to those obtained with 4000 kg.ha -1 of straw, where herbicide retention resulted in less control of ryegrass (22) .…”

The Remarkable Journey of a Weed: Biology and Management of Annual Ryegrass (Lolium rigidum) in Conservation Cropping Systems of Australia

“…Loss of efficacy of the selective ACCase and ALS inhibitor herbicides has forced growers to use pre-emergent herbicides, such as trifluralin [ 88 ]. There is a broad range of pre-emergent herbicides being used for annual ryegrass control in various crops [ 89 , 90 , 91 , 92 ]. These herbicides, from distinct groups, are commonly used in rotation between years to manage annual ryegrass populations resistant to trifluralin and to minimise resistance evolution [ 78 , 89 , 92 ].…”

Minimizing Lentil Harvest Loss through Improved Agronomic Practices in Sustainable Agro-Systems

“…Jørgensen et al (2019) [27] found that interactions between fungicide and herbicide applications were largely influenced by different farming strategies and soil conditions in winter wheat fields. Khalil et al (2020) [28] documented that stubble height and density can impact pyroxasulfone spray coverage and its efficacy. In general, rolling practices and stubble management can increase topsoil temperature and moisture, which could increase potential pathogen and weed pressure due to the relatively wet micro-climate, which in turn can interfere with the effectiveness of the pesticide.…”