甜瓜蔓枯病菌及其生物学特性的研究

甜瓜蔓枯病是甘肃白兰瓜的常发病,各瓜区普遍发生,发病率在10～65％。该病的病原菌甜瓜蔓枯病菌在PDA培养基上的菌落形态与裘维蕃先生描述的A,As一致。分生孢子有单孢、双孢、三孢3种。单孢菌株在培养中菌丝间有结合现象,即病菌有同宗配合现象。此菌的菌丝在5～35℃间均可生长,最适温度25℃;分生孢子在5～38℃间均可萌发,最适温度28～30℃;分生孢子在水滴中能很好地萌发;在pH4～9范围内均可萌发,最适为pH7;适宜浓度的马粪、蔗糖、瓜叶汁液对分生孢子萌发有刺激作用;白炽光对孢子萌发有利。病株上的菌丝有3种类型:即普通菌丝、大型薄壁菌丝和索状菌丝。在甘肃,索状菌丝是病菌的重要越冬形态和初侵染来源,而子囊座产生很少。

Studies on the Muskmelon Black Rot Fungus and Its Biological Characters

The muskmelon black rot disease (Mycospharella citrillina) was a kind of general disease in Gansu province. Disease incidence was from 10 to 65 percent in areas of culturing muskmelon. On PDA medium, the colony morphology of Mycospharella citrillina was similar to A and As which were described by Qiu Weifan. Most of conidia were two cells and the others were one or three. There was joint phenomena between mycelia, which was named homothallism by Wiant JS. The studies revealed that the temperature range of mycelial growth was 5～35℃, with the optimum of 25℃.The range of temperature and pH of conidial germination was 5～38℃, with optimum of 25～30℃, and 4～9, with the optimum of 7, separately. Free water could make the conidia germinate, but the fitter dilution of horseshit, soil, sugar and muskmelon leaf juice stimulated the conidial germination. The fluorescent light treatment favoured the conidial germination.There were three kinds of mycelia on diseased plant, which could be divided into thick-walled fasciculated, thin-walled dig and common mycelium. The first kind of mycelium was the important winter form of the fungus and the source of primary infection. A few ascomatas may procreate in some areas of Gansu.