雨水在黑胫病的重复侵染上起重要作用。烟茎上的孢子囊被雨水冲刷到地面上,释放出大量的游动孢子,随地面活水进行侵染。孢子囊只产生在较幼嫩的组织上,主要着生在烟茎顶端,其次在茎中部,茎基部分则极少发现。山东夏烟产生孢子囊的主要时期为移栽(6月底至7月初)以后到7月下旬。连续大雨有利于产生孢子囊。人工接种后4~5天是产生孢子囊的高峰。

1.Rainfall,which plays an important role in the subsequent secondary infections of black shank,is the most important factor for epiphytotics.Heavy rainfall always washes down the sporangia from diseased plants and sinks them into the soil.Whereby the rain water will spread and run over the field surface together with the inoculum.