链霉素对几种卵菌的抑制作用

用生长速率法测定，链霉素（Streptomycin）对荔枝霜疫霉菌（Peronophythora litchii）和辣椒疫霉菌（Phytophthora capsici）菌丝生长有强烈的抑制作用。在药剂含量为200－600单位／ml的PDA培养基上接种7d后菌丝生长的相对抑制率分别为87．5％－92．2％、78．2％－82．2％。用孢子萌发法测定，链霉素对荔枝霜疫霉菌和白菜霜霉菌（Peronospora parasitica）孢子囊有推迟萌发时间、降低萌发率的作用。200－600单位／ml链霉素液处理孢子囊24h萌发的相对抑制率分别为48．6％－60．8％、5．3％－10．6％，芽管的长度随药液浓度增加而缩短。200－400单位／ml链霉素防治采后荔枝霜疫病、辣椒疫病，防治效果分别为95．8％－97．1％、89．6％－91．7％。200－400单位／ml链霉素防治盆栽辣椒疫病、小白菜霜霉病，防治效果分别为82．4％－87．7％、61．8％－68．1％。

INHIBITION OF STREPTOMYCIN ON SOME OOMYCETES

Streptomycin has obvious inhibition effects on hypha growth of Peronophythora litchii and Phytophthora capsici in the experiments. Seven days after inoculation, the relative inhibition rates of hyphae growth these two pathogens on PDA were 87.5% - 92.2% and 78.2% - 82.2% , respectively , when the dosage of streptomycin was 200 - 600 units/ml. The germination of pathogen sporangia was delayed and the rate of their germination was decreased when streptomycin was applied to Peronophythora litchii and Peronospora parasitica. The relative inhibition rate of sporangium germination of the two pathogens was 48.6% - 60. 8% and 5.3% - 10.6%, respectively after treated with streptomycin for 24 hours. The length of germ tube decreased with the increase of streptomycin concentration. The results of post-harvest trial showed that the control efficacy of streptomycin on litchi downy blight and pepper blight was 95.5% - 97.1% and 89.6% - 91.7% , respectively , at rate of 200 - 400 units/ml. The efficacy of streptomycin on pepper light and Chinese cabbage downy mildew was 82.4% - 87.7% and 61.8% -68.1%, respectively, in experiment of pot cultivation.