Abstract

A pulsating release composition comprising natural microspheres, such as pollen grains or spores, into which are loaded a biologically active is subsequently releasable therefrom in a predetermined location in or on a plant or animal in a series (generally 3 or more) of pulses. In one preferred embodiment, the composition comprises a group of substantially similar loaded micropheres coated with multiple barrier layers alternating with multiple active substance layers in a concentric onion-like structure, the barrier layers being slowly soluble to delay release of active substance from the underlying layer thereof until after the pulse of active substance provided by the overlying layer has subsided. In another preferred embodiment, the composition comprises a plurality of loaded microspheres divided into as many fractions as the desired number of pulses, the loaded microspheres in each consecutive fraction being coated with a barrier layer adapted to dissolve consecutively more slowly to delay release of active substance from such fraction until after the pulse of active substance provided by the prior fraction of consecutively more soluble barrier-coated microspheres has subsided. In another aspect of the invention, the active substance-containing bodies in the compositions may be coated with one or a mixture of absorption-promoting enzymes.