Weeds compete with tobacco for water, nutrients, and space just as they do with all types of crops. Weeds may reduce cured leaf yield and quality directly by competing with tobacco for growth resources or indirectly reduce quality as foreign matter in the cured product. Weeds account for about one third of the total yield losses caused by different pests, besides causing various kinds of health hazards and damaging the ecosystem function and biodiversity. Knowledge of weed biology is essential for development of economically and environmentally acceptable weed management systems. It is said that identifying the weeds is half way to control. The first step for effective weed management is accurate identification and basic understanding of the weeds life cycle. Correct identification is an important step so that new weeds can be eradicated before they become established.
Proper weed identification helps in selecting right herbicide and time of application to control a particular weed. Sometimes identified plant may not be a troublesome weed and help in protecting conserving the biodiversity. Identification of weeds is possible with experience gained over a period of time. Unfortunately specialist assistance is not always available everywhere for weed identification. In order to overcome this problem, expert systems have been developed. The primary goal of expert systems research is to enable decision makers and technicians to do the job more efficiently. The expert system technology is a new approach for weed identification.