A procedure for the rapid screening of strawberry seedlings for resistance to Verticilluum wilt

Summary

A technique is described which promises to be of great assistance in breeding for resistance to verticillium wilt in strawberries.

Strawberry seeds were sown on moist terylene wool, covered with black polyethylene beads and suspended over aerated liquid nutrient solution. Good germination of the seeds occurred, and the seedlings developed rapidly reaching the third-leaf stage with a well-established root system after 45 days. At this stage, the seedlings were inoculated with pathogenic isolates of Verticillium dahliae Kleb, by immersing the root systems in a conidial suspension (100000/ml) for 1 h, then replacing the seedlings in the liquid nutrient solution. Wilt symptoms, i.e. leaf wilting and necrosis, were first observed on the most susceptible seedlings 21 days after inoculation. All seedlings were re-inoculated 35 days after the initial inoculation, and those which were visually healthy 50 days later were graded as tolerant and subjected to further tests.