- Author: Konrad Mathesius
Summary Review
Results from this year's Italian ryegrass (IR) herbicide trials helped quantify differences in herbicide resistance among IR populations within the southern Sacramento Valley. The trial took place in Bird's Landing, CA (near Rio Vista), and was replicated farther north in Esparto, CA.
- Trials from this year suggest that Osprey-resistant IR populations often associated with the area around Dixon, CA could extend at least as far south as Bird's Landing with only 26% control of IR by Osprey in the trial site.
- The Osprey-resistant population appears to also be moderately resistant to Simplicity, another herbicide in the same chemical...
- Author: Konrad Mathesius
Summary note: This is a belated research update from herbicide trials (targeting Italian ryegrass) carried out in the winter of 2021-2022 in wheat fields in the Esparto area. The southern Sacramento Valley saw a record number of consecutive days without rain in that year, which severely limited the efficacy of post-emergent systemic herbicides. Growers should prioritize scheduling post-emergent herbicide applications early in the weed's growth stages and when weeds are actively growing to avoid the severe reduction of herbicide efficacy that can occur as a result of unexpected droughty conditions. This is particularly important given that the weather systems in our...
- Author: Clebson G Goncalves Ph.D.
- Posted by: Gale Perez
In California, Italian ryegrass [Lolium perenne L. spp. multiflorum (Lam.) Husnot] has been around for a long time and is a major weed in orchards, vineyards, field crops, fallow fields, and so on. It grows vigorously in winter and early spring. Italian ryegrass is a short, rhizomatous, that grows from 11 to 35 inches tall, often with erect stems exhibiting purple coloration at the base. That species can be identified by its dark green, glossy, and hairless leaves that are rolled in the bud. Auricles are well-developed and the shape can vary from clasping to blunt, and the ligules are long and membranous. Once flowering occurs, Italian ryegrass is easily distinguishable by alternating spikelets that run along the...
- Author: Konrad Mathesius
- Posted by: Gale Perez
Controlling Italian Ryegrass in California Small Grains Field Day
Thursday, April 21, 2022, 8:45 a.m.–10:45 a.m.
POSTPONED to Friday, April 22, 2022, 8:45 a.m.–10:45 a.m.
Intersection of
- Author: Konrad Mathesius
- Contributor: Thomas Getts
- Contributor: José Luiz Carvalho de Souza Dias
- Editor: Brad Hanson
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Concerns about a growing resistance to herbicides
In Mediterranean or arid climates, particularly in areas with marginal soils, crop rotations are often limited to a narrow range of hay, pasture, a handful of winter legumes, or rainy-season grasses. Arid conditions and weathered soils drove Australia's rainfed grain growers to adopt no-till strategies earlier than their counterparts in California. While beneficial from a water use perspective, successful no-till systems depend on herbicides to control weeds that were traditionally kept in check with tillage.
Dependence on herbicides alone in these systems has resulted in weeds with resistance to multiple modes of action. In Australia, there is one...