COVER CROPS in South African Vineyards

CHAPTER 5 WEED CONTROL

FIGURE 5.1. Comparison of two different weed-control strategies in combination with a cover crop of rye ( Secale cereale ). In the foreground, chemical control was applied just before bud-break, whereas in the background chemical control was applied at the end of November. It can be seen that weeds, mainly ryegrasses ( Lolium species) are proliferating in the latter treatment. Photo from Fourie (2015). Perennial dwarf fescue reduced the stand of winter-growing weeds in the Breede River valley, but did not control summer-growing weeds. As previously discussed, perennial cover crops are not recommended, because they tend to become infested with weeds, consume water during the grapevine-growing season, and impact negatively on grapevine performance. Studying the effect of different cover-crop management practices on specific weed species showed that problem weeds, such as the ryegrasses and common couch, can be suppressed or controlled by applying the correct combination of a winter-growing annual cover crop and chemical control during grapevine bud-break and berry set. However, problem weeds that germinate mainly during mid to late summer must be controlled over the medium term by another application of a post-emergence herbicide during December or mid-January. Reference list Fourie JC. 2015. Soil tillage, cover crops and weed control as part of an integrated approach to the cultivation of grapevines. Part 3: Amount of irrigation water needed per hectare as affected by soil management. Wineland July, 76–79.

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