Weed Management in Horticultural Crops

Course Overview

Welcome to the course of "Weed Management in Horticulture Crops". Weeds are plants that are unwanted in a given situation and may be harmful, dangerous or economically detrimental. Weeds are a serious threat to primary production and biodiversity. Some may release toxic chemicals, which may adversely affect the crop growth, while the inclusion of undesirable weeds during harvesting can reduce crop quality and appearance. Even with good farming practices weeds may reduce the crop yield by 10% to 20%, but, if poorly controlled, they can reduce yields by as much as 80%.The impact of weeds on crop yield varies according to the weed species present, their density and their persistence during the cropping cycle. In general, weed competition during the early stages of crop growth is much more harmful than during the later growth stages. They reduce farm productivity, displace native species and contribute significantly to land and water degradation. The costs of weeds to the natural environment are also high, with weed invasion being ranked second only to habitat loss in causing biodiversity decline. A major failing on the part of many growers is to commence weed control too late - when weeds are already well-established. Early control is essential for best results; there is less competition with the crop, and the weeds are still tender and more easily killed.
Despite considerable government and private sector investment, weed invasion still represents a major threat to both the productive capacity of land and water and the integrity of our natural ecosystems. An efficient weed control programme can only be developed after the weed has been properly identified. Weeds can be managed using many different methods. The most effective management of weeds is usually achieved through collaboration and co-operation in partnerships between the community, land owners, agriculture, industry and the various levels of government, using a combination of methods in conjunction with a thorough follow-up campaign. There are many situations in which some of the weed species present cannot be controlled chemically. However, by judicious rotation of crops and the selection of a chemical to which the main weeds present are susceptible, such weed problems can frequently be overcome. Thus, crop rotation and herbicide changes together form a simple, effective method for obtaining good weed control in the long term.
Weed management is an important component of plant protection improving the production potential of crops. It includes management of the weeds in a way that the crop sustains its production potential without being harmed by the weeds. Weed management is done through the mechanical, cultural and chemical means. Use of biological control methods in field crops is being considered, but still not much in use. Use of herbicides is an important method in the modern concept of weed-management technology. New hand-tools and implements have also been designed to assist in weed-management programme.