Abstract: Method and apparatus for protecting plants against the effects of a drop in ambient temperature by causing the formation and preservation of dew or rime, according to the circumstances. The apparatus comprises a "dew box" which measures the ambient temperature and the dew point temperature, a set of comparators for triggering the start of spraying and the start of water heating as a function of ambient temperature, and a control system, including a calculating device, for regulating the temperature of the spraying water.

Abstract: An irrigation control apparatus, particularly suited to drop-by-drop irrigation, is provided and which comprises an assembly for electrically controlling the starting and stopping of an irrigation system by means of two electrodes which are spaced both vertically and laterally from each other. A "bulb" of humid soil is produced during irrigation and the upper electrode of the two is laterally off-set with respect to the axis of symmetry of the bulb, by a distance equal to at least half of the maximum radius of the bulb, and is situated at the upper limit of the bulb. The lower electrode of the two is arranged in a diametrically opposite position, at a point laterally off-set with respect to the said axis, but in the inverse sense, also by at least half the maximum radius of the bulb and is situated at the lower limit of the bulb.The precise relative positions of the electrodes are determined by the shape of the bulb which in turn depends on the nature of the soil to be irrigated.