The hypovirulent strains have less competition capability compared with virulent ones in natural world by the facts of hyphae growth slowly and spores production difficulty.

• 栗疫苗弱毒菌系在自然界的传播受诸多因素的影响，弱毒菌株菌丝生长较慢，产孢能力较低，因而同强毒力菌系竞争的能力较弱。