【摘要】 荔枝霜疫病病原菌在11～30%均可形成游动孢子囊,在22～25℃时,孢子囊产量最高,孢子囊在8～22℃间均能萌发形成游动孢子,但在26～30℃时萌发则形成芽管。在8～16℃间的萌发率最高。游动孢子的形成在14℃下只需20分钟,10℃下只需30分钟,游动孢子从形成至释放在14℃及10℃下所需时间分别为10分钟及20分钟。荔枝霜疫霉在侵染过程的各个时期中,都要求高湿度,否则不能危害,在高湿条件下,此菌在11～30℃均可侵入荔枝果,在18℃下只需5分钟便可侵入。最适扩展温度为25℃,在25℃下,潜育期不到1天,在18℃下为2～3天,在11℃下可延长到7天,在30℃潜育期虽短,但产生的孢子囊数量很少,出现期只有1天。危害荔枝果的接种体主要是游动孢子,荔枝结果期间的5月,多连雨天,病原菌的再侵染频繁,可能是荔枝霜疫病在广州地区经常流行的主要原因。更多还原

【Abstract】 In recent years,Downy blight of litchi has become one of the mostserious diseases of fruit crops in Guangdong Province.The pathogen notonly attacks the ripe fruits but also the young fruits,pedicles and leaves.Detailed studies have been made on its morphological and biological cha-racters of this fungus,the fungus now is identified as Peronophythora litc-hii Chen ex Ko et al.but the growth of sporangiophores are indetermi-nate,tubercles and chlamydospores are formed in mycelium,and it infectsthe fruits of Carica papaya,Lycopersicum esculentum,and Luffa cylindricain artificial inoculation.Sporangia are produced between 11～30℃,how-ever,the greatest numbers of sporangia are produced between 22～25℃.The sporangia germinate by zoospores formation between 8～22℃,and bygerm tube between 26～30℃,while at 24℃,sporangia germinate both direct-ly by germ tube and indirectly by production of zoospores.The forma-tion of zoospores in sporangia with 7 days old culture is evident at14℃ for 20 min and at 10℃ for 30 min.The time required for relea-sing zoospores is 10 min.and 20 min.at 14℃ and 10℃.respectively.Under high moisture,the fungus is able to penetrate into litchi fruitsbetween 11～30℃,it requires only 5 min.at 18℃ the optimum tempe-rature for formation and enlargement of the lessions is 25℃.The incu-bation period is less than one day at 25℃,and 2～3 days at 18℃,at11℃ the incubation period prolonges to a week,at 30℃ though short,the numbers of sporangia are few.Reproduction period is only one day.The fungus invades litchi fruits depending on the zoospores,the infection process is extremely short.The continuous raining andfrequent reinfection in May of litchi-growing season are probably thefactors of utmost importance for the epiphytotic of the disease inGuangzhou region.更多还原