Weeds need to be adequately controlled because they are efficient competitors with the crop for nutrients, moisture and sunlight. Some of them might be hosts of pests and diseases of tomatoes, or they might provide shelter for insect pests. It is very important that weeds be controlled in the early stages of crop development, because early competition can more seriously affect plant growth, and result in the lowering of crop yields. Weed growth can also hinder the correct application of pest and disease chemicals, which are usually necessary in the production of tomatoes.
In most instances, weeds are controlled by means of mechanical and/or hand cultivation. Such cultivation needs to be started timeously, before any damage to the crop results from competition. The row spacing selected, especially in the larger plantings, is often such that mechanical weed control can be practised in the inter-row area during the initial stages of growth, with hand-hoeing or hand-pulling of weeds being applied in the plant rows. Because tomato feeding roots are wide-spreading and shallow, mechanical cultivation should preferably be discontinued in well-established plantings.
Chemical weed control is not normally practised in KZN. Nevertheless, there are a number of herbicides which are registered for use in tomato plantings.
Pre-plant - trifluralin (sold as Trifluralin, Triflurex 480 and Digermin) sprayed onto well-prepared soil and incorporated immediately, for control of annual grasses and some broadleaved weeds.
Early post-emergence - metribuzin (Sable 480, Sencor 480 and Contrast Turfgrass) applied between rows a fortnight after transplanting, against annual grasses and broad-leaved weeds.
Haloxyfop - R - methyl ester (Gallant Super and Verdict Super); control grasses when young Rimsulfuron (Cato); against young annual grasses and broad-leaved weeds.
Cycloxydim (Focus Ultra); against grasses
WEED CONTROL
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