  Agricultural production has become a complex business that requires the
accumulation and integration of knowledge, in addition to information from many
different sources. To remain competitive, the modern farmer often relies on
agricultural specialists and advisors who provide them with information for
decision making in their crops. But unfortunately, the help of the agricultural
specialist is not always available when the farmer needs it. To alleviate this
problem, expert systems have become a powerful instrument that has great
potential within agriculture. This paper presents an Expert System for the
diagnosis of diseases and pests in rice, tobacco, tomato, pepper, corn,
cucumber and bean crops. For the development of this Expert System, SWI-Prolog
was used to create the knowledge base, so it works with predicates and allows
the system to be based on production rules. This system allows a fast and
reliable diagnosis of pests and diseases that affect these crops.
