一、霜霉病的发生特点。1.霜霉病菌的生存条件:黄瓜是比较喜湿喜温作物,特别是进入开花结果期,需要有较充足的水份才能满足黄瓜的生理需水,而霜霉病菌也正是在高湿的条件下孢子囊形成加快,如相对湿度达到83%以上,经4小时就能产生孢子囊。因此,高湿或叶面存有露水,是霜霉病流行的必要条件。另外,病菌对温度适应范围较广,在叶面存在水滴的条件下,温度在5～32℃时,孢 First, the occurrence of downy mildew characteristics. 1. Downy mildew germs living conditions: cucumber is more like the wet hi temperature crops, especially into the flowering period, the need for adequate water to meet the cucumber physiological needs of water, and downy mildew bacteria is also in high humidity The formation of sporangia to speed up, such as the relative humidity of more than 83%, after 4 hours can produce sporangia. Therefore, high humidity or foliage dew, is a necessary condition for downy mildew epidemic. In addition, the bacteria to adapt to a wide range of temperature, the presence of water droplets in the foliage conditions, the temperature at 5 ~ 32 ℃, spores