Five soil management practices applied in a micro-sprinkler irrigated 'Pink Lady' (Cripps Pink/M7) orchard established on a loam soil near Grabouw were evaluated from October 2003 to March 2010. Dry matter production by the cover crops at the end of September was higher under integrated soil management (IP) than under organic soil management (Organic) during 2004, 2007 and 2008, with the same trend being observed during 2005, 2006, and 2009. Cover crops in the IP and Organic treatments suppressed the winter growing weeds significantly over all seasons compared to treatments in which no cover crop was sown and weeds were slashed during the growing season of the trees (Weeds (IP) and Weeds (Organic) treatments). Except for September 2004, a similar result was achieved where a full surface straw mulch was packed out annually during October, followed by hand weeding during the growing season of the trees (Straw Mulch (Organic) treatment). Summer growing weeds were controlled effectively by the Cover Crop (IP) and Straw Mulch (Organic) treatments. Weeds (IP) and Weeds (Organic) caused broad leaf weeds to disappear and perennial grasses to dominate the weed spectrum. Although not as drastic, a similar trend developed in the Cover Crop (Organic) treatment. In contrast, annual weed species became dominant where Cover Crop (IP) was applied. All soil cultivation practices caused changes in the weed spectrum, with species dominance shifting with time. This aspect of weed control should be studied more extensively in future.
