Pests and Diseases of Prehistoric Crops: A Yield ‘Honeymoon’ for Early Grain Crops in Europe?

Before the agricultural improvements of recent centuries, grain yields in medieval Europe appear to have been extremely low: well below the full potential of the crops. If yields were similarly low in prehistory, the adoption of cereal cultivation could have conveyed few benefits in terms of productivity. Consideration of the key constraints on cereal yield highlights the previous neglect of the role of pests and diseases. It is suggested that these may have been particularly damaging in the medieval period, but much less so during the early stages of the adoption of agriculture.
Textual and archaeological evidence for the past occurrence of pests and diseases is discussed and, combined with consideration of the development of pest and pathogen problems of recent crop introductions, used to provide a possible outline of the early development of the pest/disease burden. It is suggested that when grain crops were first introduced into temperate Europe there may have been a 'honeymoon period' with high yields: pests and diseases which had been endemic on cereals in semi-arid, continental, or Mediterranean climates did not thrive in the temperature climate, while species native to north-west Europe may not have been adapted to attack cereals. Subsequently, however, some pests and diseases evolved to attack cereals in this environment. These may have prompted changes in grain production methods to reduce the risk of damage. Pests and diseases must have been a driving force in agrarian change for several millennia, and cannot be ignored in attempts to understand the history of agriculture.