松、杉、柏等针叶树苗,在严冬之后,往往发生枯黄死亡的现象.其原因是,早春气温回升,而土壤尚未解冻,苗根很难从土壤中吸收到水分,地上部分又开始蒸腾,使苗木严重失水、造成“生理干旱”而干枯死亡.过去,不少地方对针叶树苗的这种冻害,采取的措施是复土、盖草或设防风障等,每亩亩地大约需用稻草1000—1500斤,不仅消耗物力、资金和人工,而且因土压、复草时损伤苗木,同时发生烂叶或烂根,经济效益降低.为了投资小,效果好,经试验,对针叶树苗喷洒波尔多液涂白防寒,既简单,又能达到“一药多用”的效果. Pine, cedar, cypress and other conifers, after the severe winter, the phenomenon of yellow death often occurs.The reason is that the temperature rose in early spring, while the soil has not yet thawed, it is difficult for seedling roots to absorb moisture from the soil, the aerial parts began to transpiration, So that serious nuisance water loss, resulting in “physiological drought.” In the past, in many places on the coniferous frost damage, the measures taken are re-soil, cover grass or windbreak, etc., about mu per acre need 1000-1500 kg of straw, not only consume material and financial resources and labor, but also because of soil pressure, Fuso damaged seedlings, rotten or rotten roots occur at the same time, reduce economic efficiency.In order to invest small, good effect, the test, the conifer Spraying Bordeaux solution coated white cold, both simple, but also to achieve “a drug multipurpose” effect.