ABSTRACT
Problems caused by weeds may be categorized into seven main areas:
Competition between the weed and the plant for water, nutrients and light may prove favourable to the weed if it is able to establish itself quickly. A large cleaver plant ( Galium aparine ), for example, may compete for a square metre of soil. The cultivated plants are therefore deprived of their major requirement and poor growth results. The extent of this competition is largely unpredict able, varying with climatic factors such as temperature and rainfall, soil factors such as soil type, and cultural factors such as cultivation method, plant spacing and quality of weed control in previous seasons. Large numbers of weed seeds may be introduced into a plot in poor quality composts or farmyard manure. The uncontrolled proliferation of weeds will inevitably produce serious plant losses.
