The Ht-Toxins produced by Helminthosporium turcicum in vitro could significantly inhibit the growth of roots and buds and kill isolated root cap cells of corn.

• 玉米大斑病菌在活体外产生的致病毒素（Ht－毒素）不仅能抑制玉米幼苗根和芽的生长，而且对玉米离体根冠细胞也有明显的致死作用。