Contagious seedlings, density of copula during earlier period and repeated infection during growth period were three inportant parts of prevalence, but early rice was different from late rice.

• 感病秧苗、大田前期介体灰飞虱密度以及本田期再侵染是本田病害流行的3个重要部分，但早、晚稻有所不同；