- Author: Konrad Mathesius
- Contributor: Thomas Getts
- Contributor: José Luiz Carvalho de Souza Dias
- Editor: Brad Hanson
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...
Italian ryegrass is a major weed in orchards, vineyards, field crops, and fallow fields of California (Figure 1). Several different herbicides are used to control ryegrass and had been effective in reducing infestations until resistance evolved in many populations following repeated use of the herbicides. To date, resistance to glyphosate, paraquat, and some ACCase and ALS inhibitors has been confirmed in ryegrass infestations across the agricultural landscape of California. To make matters worse, resistance to multiple postemergence herbicides with different modes of action has been confirmed within the same orchard, vineyard, or field in some areas. Consequently, management of Italian ryegrass in California annual and perennial...
- Author: Mariano Galla
Last winter, many growers and PCAs contacted me because they were having trouble or were largely unable to control Italian ryegrass (Lolium perenne ssp. multiflorum) in their cereal fields. This grass species (see Photo) is widely spread throughout the Sacramento Valley in orchard and field crops and it can be particularly problematic in winter cereals, as it can reduce yields by 80%, by competing for water and nutrients.
Italian ryegrass is a really tough weed and the application timing is extremely important. Osprey, Simplicity and Axial are usually effective. However, all these herbicides will not work if applied when the ryegrass population in your field...
- Author: Mariano Galla
Italian ryegrass (Lolium perenne spp. Multiflorum), is an annual grass common in Sacramento Valley orchard and field crops (Figure 1). This species germinates and matures approximately at the same time as winter cereals and is highly competitive for soil nutrients during the time when wheat is tillering. It can also interfere with harvest and it has been reported that Italian ryegrass can cause up to 80% reduction in winter wheat grain yield due to competition for nutrients and water (Liu et al., 2016)
During this time of the year when your wheat is tillering, it is really important to monitor fields for weeds and Italian ryegrass infestations in particular.
Information about weed management can...