CREATE TABLE table_18309 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

What other cadidate ran against Dave Treen?
SELECT "Candidates" FROM table_18309 WHERE "Incumbent" = 'Dave Treen'
SELECT "Candidates" FROM "table_18309" WHERE "Incumbent" = 'Dave Treen'