Oat seed germination tests in rolled paper towels at 24 degrees to 28 degrees C (75.2 degrees to 82.4 degrees F) have given a reliable estimate of seedling damage by Helminthosporium victoriae and H. avenae. Sufficient disease does not develop at 20 degrees C (68 degrees F) and below to secure a reliable disease rating from the germinator especially for H. victoriae. Germination tests at high temperatures offer a rapid means of estimating seedling damage from seed-borne inoculum of these fungi. The method is applicable in the evaluation of seed lots for seed use and as a guide for recommendations of seed treatment. In evaluating seed lots for seed certification by the Wisconsin Certification Agency, oat seed lots are germinated in moistened rolled paper towels by placing in the refrigerator for 4 days then transferring to 80 degrees to 82 degrees F (28 degrees C) for 4 days after which they are read for disease development. Seed treatment with the volatile, organic mercury compound Semesan Jr., reduces the seed-borne inoculum, but does not eliminate it in badly diseased seed lots even after 14 days storage after treatment.