内吸杀菌剂根系打浆防治松针褐斑病

湿地松或火炬松1年生苗,用一定浓度多菌灵或甲基托布津泥浆根系打浆处理,然后定植于苗圃中。30～50天后接种松针褐斑病菌(Lecanosticta acicola),又经50天左右检查感病情况;或将处理苗定植于发病林地上,任其自然发病,每年检查感病情况,共2～3年。所有杀菌剂处理浓度,在短期或1年内均可显著降低松针褐斑病的侵染,当年松苗感病程度与杀菌剂处理浓度没有明显相关性。但第2年或第3年,松苗感病程度随时间而增加,且与杀菌剂处理浓度呈明显负相关。结果表明,松苗定植前用含有效成分3％～5％多菌灵或含有效成分5％～10％甲基托布津泥浆处理根部,可在2～3年内有效地防止松针褐斑病的侵染。

THE SYSTEMATIC FUNGICIDE ROOT-DIP TREATMENT CONTROLS BROWN-SPOT NEEDLE BLIGHT

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.