 Because these models are necessarily simplifying natural conditions (often based on the assumption that weeds, disease and insect pests are controlled), it is not clear whether the results they give will have an "in-field" reality.However, some results are partly validated with an increasing number of experimental results.Other models, such as "insect and disease development" models based on climate projections are also used (for example simulation of aphid reproduction or septoria (cereal fungal disease) development).