青椒疫菌为北京地区青椒死秧的主要原因

 研究了北京郊区东升、温泉、小红门、四季青等乡的温室和露地青椒死秧病原形态和培养特性、生长温度-接种方法、寄主范围。证明孢子囊形态变异较大,病株及新鲜瓜果上为枣核形、长椭圆形等.长宽比为1.5—1.9:1.乳突明显(高3.1—5.0μm),少数双乳突.多数带有长柄(31—42.6μm),厚垣孢子不产生或很少产生,该菌为异宗结合。卵孢子球形,淡至金黄色,直径15.0—28.0μm。以鲜菜豆,燕麦片培养基上生长最好。25—32℃为生长最适温,低于10℃和高于37℃不生长。致病性测定:能侵染青椒、番茄、茄子、黄瓜、辣椒等8科19种植物,寄主范围广,致病力强.在对比不同种的特征基础上确定青椒疫病系Phytophthora capsici.室内药效测定表明瑞毒霉作用最明显,其次多为菌灵、乙磷铝,百菌清抑菌效果差.

THE MAIN CAUSES PHYTOPHTHORA CAPSICI AS ONE OF CAPSICUM PLANT WILT IN BEIJING REGION

This paper demonstrates that Phytophthora capsici is the chief cause of the capsicum plant wilt in Beijing.The isolates were obtained from green-house and field diseased plants in Dongsheng,Wenquan,Xiahongmen and Sijiqing,and their cultural and morphological properties were studied.The sporangia vary in size,length/breadth being 1.5-1.9:1,usually with single papilla,sporangia mostly with long sporangiophore (31-142.6 μm),No chlamydospores produced or produced rarely.This fungus is heterothallic.The oogonia are spherical,15.5-28.9μm in diameter.Oospores are spherical,yellowish to golden,15.0-28.0μm in diameter.The optimal temperature for growth is 25°-32℃,with low and high limitation of 10℃ and 37℃ respectively.Fungus has a rather wide host range including 8 families 19 species.By comparing with the properties of various Phytophthora species,this fungus was identified as Phyiophthora capsici.The fungus is very sensitive to Ridomil,Bavistin and Aliette in laboratory experiments,while the Daconil is the least effective.