落叶松早期落叶病子囊孢子扩散形式及药剂防治试验的初步研究

落叶松早期落叶病子囊孢子在空中的扩散,在长春地区,以7月份为盛期。林外水平距1600米及垂直高55米处均可捕捉到不低于林内孢子的数量,其方向符合夏季主风方向。噴药防治的效果,无論成林或幼林,均以0.5度石灰硫黄合剂最好,尤其噴药3次的更佳。地面噴药抑止产生子囊壳,以3度石灰硫黄合剂及每株20克石灰比二硝基磷甲酚效果好。

PRELIMINARY STUDIES ON THE DISPERSAL PATTERN OF ASCOSPORES OF MYCOSPHAERELLA LARICI. LEPTOLEPTIS AND THE EFFECTS OF FUNGICIDAL CONTROL

The needle-cast disease of Laricis leptolepis caused by the fungus Mycosphaerella laricileptolepis Ito, Sato, and Ota, is widely distributed in North-East provinces. The primary infection of the pathogen is mainly the ascospores from the fallen leaves on the ground during the spring. In order to determine the distance of its vertical and horizontal discharge of the spores from the perithecia, a simple spore-trapping method was designed by exposing the glass slides in six directions, placed in three different locations and six different heights. Preliminary data showed that the ascospores could reach a height of 55 meters and a distance of 1600 meters along the wind direction. Among the 20 fungicides tested in the field on both young and large trees, 0.5°Bê limesulphur spray employed three times at 2-weeks interval gave a very good control. A ground spray on fallen leaves by six different fungicides did not give satisfactory results although 3°Bê lime-sulphur and lime (20 grams per tree) appeared to be better than dinitro-phosphatemethyl-phenol.