Abstract: Roots of Pinus elliottii or P. taeda 1 yr seedlings were dipped in a mixture of carbendazim or thiophanate-methyl and clay before planting for brown-spot disease control. Disease indexes of the treated seedlings were evaluated about 50 days after artificial inoculation with Lecanosticta acicola or annually for 2-3 yr under natural infection. Each concentration of the fungicides was effective for reducing the infection in a short stage of the first yr. The control effect was gradually reduced in the second and third yr. There was no evident correlation beetween disease indexes and concentration of the fungicides in the first yr. But the disease indexes were negatively correlated with concentration of the fungicides in the second and the third yr. It is recommended that 3-5% a. i. carbendazim or 5~ 10% a. i. thiophanate-methyl root-dip treatment before planting should provide an effective control of Lecanosticta acicola.