Source: Weed Technology

The best method to combat weeds is not one method, but a combination of approaches. "Integrated weed management" merges several single-management strategies, such as crop rotation, optimal timing of planting, spacing of crops, and chemical weed control, to successfully suppress weeds. A variety of combinations were tested in a study of jointed goatgrass in wheat crops in the Pacific Northwest. In Washington and Oregon, the goatgrass weed was controlled without the use of an in-crop herbicide.

An article in the current issue of the journal Weed Technology presents the results of a six-year study evaluating eight integrated weed management systems in winter wheat crops in Idaho, Washington, and Oregon. Differentiations in rainfall and initial weed population led to different solutions for the three sites.

In this study, actions such as burning off a field, leaving the field fallow part of the year, and planting rotations of winter wheat or spring wheat were included among the integrated strategies. Nonstandard, integrated control methods for planting included adding nitrogen, using competitive wheat varieties, increasing the seeding rate, and using large seed.

Wheat growers in this region could see an increase in farm profits by adopting integrated weed management systems. In the Oregon study, winter wheat yield increased 23 percent in the second year following a strategy of burning off field stubble, planting spring wheat and leaving the field fallow until planting winter wheat using integrated practices. Additionally, weed seeds in the grain were reduced 92 percent and plant density was reduced 86 percent.

The overall goals of an integrated weed management system include maximizing the profit margin, reducing dependence on herbicides, and reducing not only weed growth but also weed seed production and seed reserves in the soil.

Full text of the article, “Integrated Weed Management Systems Identified for Jointed Goatgrass (Aegilops cylindrica) in the Pacific Northwest,” Weed Technology, Volume 24, Issue 4, October-December 2010, is available here.