Technical Yearbook 2023

OCTOBER

Let nature work for you – employ winter weeds as cover crops By Hennie Visser

Rising input costs and pressure on producers to lower their synthetic footprint in the vineyard, have compelled wine grape producers to think outside the box to farm sustainably and successfully. The use of certain winter weeds as cover crops appears to be a pragmatic alternative for cultivation regions with erratic winter rainfall. The benefits of a good cover crop stand have been well documented and range from weed control, increased water infiltration, decreased surface evaporation, higher soil carbon content to reduced erosion, to name but a few. Unfortunately for producers in the irrigation areas like the Breede River, Klein Karoo and Olifants River, they obtain mixed results from cover crop cultivation, often due to insufficient and sporadic winter rainfall. Considering the rising input costs related to commercial cover crop cultivation, some producers have converted to a free alternative; the use of local winter weeds to perform the work of a cover crop. The two species that are most often used for this purpose, are wild barley ( Hordeum murinum ) and Australian saltbush or creeping saltbush ( Atriplex semibaccata ). Wild barley Wild barley is an annual grass originally from Europe and is commonly found in the Western Cape and the rest of South Africa. It is a winter tufted grass with a low growth habit, but can reach up to 60 cm in length. This winter grass re establishes easily, even in times of low winter rainfall where seed production is still noteworthy despite the lower stand. Producers also often harvest the seed heads to establish these in the desired areas during the following autumn, often without seedbed preparation and fertiliser. The wild barley stand can be gradually improved by, selectively, controlling winter broadleaf weeds where necessary, and applying focused spot sprayings where other species offer significant competition. With this systematic approach, an excellent natural stand can be obtained within a few seasons. One of the outstanding advantages of wild barley is the relatively short growth cycle and the subsequent low level

PHOTO 1. Wild barley natural cover crop.

PHOTO 2. Dead wild barley mulch.

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TECHNICAL YEARBOOK 2023