To spread widely as if by sowing seeds.
Example:
Television and computer networks now make it possible to disseminate information throughout the world very quickly.
In disseminate, the prefix dis- keeps its original Latin sense "apart." This prefix was attached in Latin to the verb seminare, "to sow," which itself was derived from the noun semen, "seed." The image lying behind disseminate is that of a farmer sowing seeds over a wide area by throwing them with a sweep of the arm, the same image that has given us broadcast (which has the basic sense "to cast broadly"). It's appropriate, then, that one of the best ways to bring about the dissemination of news is by broadcasting it over television and radio.