The Republic of Yemen is divided into six regions, though the borders are not clearly distinctive mainly in the western escarpments, they are recognized as five regions as follows; the coastal areas and Tihama region, the Western escarpments (lower and upper escarpments) and Southern Uplands region, the Highlands (Central and Northern Highlands), the Eastern Escarpments and desert (Ar-Rub Al-Khali) region, and the groups of Islands with special reference to Socatra Island There are eight agro-ecological areas.
More than sixty crops are grown in the country using mostly traditional methods, and recently few farmers are implementing new agricultural technologies. Certain changes occurred in the different agricultural ecological zones of the country to meet the new policies aiming to be self-sufficient These have led to the introduction of new crops and the disappearance of some of the local landraces of some crops. Nevertheless, new races of pathogens were introduced or emerged in the different agro-ecological zones. Surveys of economically important diseases and causal pathogens in the Republic of Yemen have previously been undertaken and the results of these surveys together with new records carried by the authors recently are presented. More than five hundred disease records are listed, of these, thirty diseases severely attack their host crops.