Figure 1.

Reduction of TMV lesion size by pretreatment with F 500. On two tobacco plants, one-half of a leaf was infiltrated with an aqueous suspension of F 500 at 0.25 or 0.5 mm. The remaining halves of the leaves were infiltrated with water. Twenty-four hours later, both halves of the two leaves were infiltrated with a suspension of TMV (1 μg mL⁻¹) by gently rubbing two layers of cheesecloth soaked with TMV suspension over the carborundum-covered leaf surfaces. The leaves then were washed under a stream of tap water. The size of developing lesions (±se) was examined with a fluorimager 7 d later as described in “Materials and Methods.”