Precision Agriculture is an agricultural practice that uses technology based on the principle of variability. The geographically referenced data implement the process of agricultural automation so as to dose fertilizers and pesticides. The efficient application of low cost pesticides without contamination the environment is an agricultural production challenge. The main effect to be avoided during application is pesticide drift. To minimize it is important to know the environmental conditions, such as wind, temperature, and humidity at the moment of application. This article discusses and proposes the use of Wireless Sensor Networks in a support and control system for pesticide application. A Wireless Sensor Network is a special kind of ad hoc network, consisting of several sensors that collect and process information from the environment which it is distributed. These sensors are use to record different data types, such as temperature, humidity, wind speed and direction. Three uses of the application of sensor networks in precision agriculture are investigated. In the first case, the sensor network evaluates environmental data at the time of application to determine suitable environmental conditions for application. The system monitors throughout the application and in addition emits an alert when the environment is unfavorable for the application. The second use evaluates the wind speed and direction to suggest corrections in the path of a tractor or aircraft. It is expected that this alteration in the path results in applying the defensive solely in the appropriate area. The last use of the sensor network that will be discussed here analyzing crop dusting quality by evaluating the deposition of pesticide over the crop. The use of sensor networks in precision agriculture has become an important management tool. Wireless Sensor Networks can be used in crop dusting, in order to minimize and control pesticide drift, and the contamination of soil and waterways, improving effective application.