Dry conditions this year have generated common questions from growers such as “when should I irrigate to maximize yield?” and “will I be able to take this crop to seed?” Many of the principles that dictate irrigation strategies in wheat are similar to those of other crops. Understanding wheat's growth stages can help growers develop a strategy for drought years.

Important Physiology

Relative to many crops, small grains are considered plastic, or flexible, in their growth habit and yield potential. This means that the crop adjusts its growth to the scarcity or abundance of resources (water and nutrients) encountered during the season. The impacts of stress on crop yield are not...

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...

Summary Note

Mechanical cultivation is a useful tool in controlling herbicide-resistant Italian ryegrass individuals in a rainfed wheat system but is only about half as effective as Axial in reducing overall pressure from Italian ryegrass (expressed as a percentage of total groundcover). Growers should consider multiple approaches (chemical and mechanical) and integrate IPM strategies to reduce the spread of resistance among Italian ryegrass individuals. 

Background

Italian ryegrass (Lolium multiflorum)  has been shown to be a persistent weed for growers in rainfed winter grass...

If growers sprayed for Italian ryegrass earlier this year, it might still be worth keeping an eye out for it in fields and field margins.

Italian ryegrass (Lolium multiflorum) is an annual grass that can sometimes behave as a biennial or short-lived perennial in California. The species is an upright grass (to about 3 feet in height) that germinates in the late fall and grows vigorously through the winter and early spring. The species can be identified by its dark green, glossy and hairless leaves that are rolled in the bud. Auricles are well-developed and the ligules are long and membranous. Once flowering occurs, ryegrass is easily distinguishable by alternating spikelets that run along the length of the main...