银杏疫病的研究

On Ginkgo biloba Wilt Caused by Phytophthora

关键词:  银杏  疫病  病原菌

Key words:  Gingko biloba  Gingko biloba wilt  Phytophthora sp.

摘要:

对银杏苗圃中发生苗枯的植株进行病原分离及回接试验,发现引起银杏苗枯的病原为Phytophthorasp.称这种苗枯为银杏疫病。该病危害银杏幼嫩苗木的地上部分,未见危害根部和多年生成林树。叶片受害似开水烫伤状,茎干受害则变黑,黑色病斑环绕茎干一周后,病茎以上部分叶片青枯萎垂。病原菌在PSA培养基上,菌落白色绒毛状,28℃下7d可长出大量孢子囊,易产生厚壁孢子,病菌生长适宜温度为24℃~32℃。人工接种可致受伤银杏叶片及幼嫩茎干严重发病,但无伤茎叶发病较轻或不受害。在田间,该病5月初开始发生,3d~5d病情达到高峰,苗圃的发病率为10%~20%,有明显的发病中心,5月底病情稳定,以后病害不再发生。用含药培养基及含药纸碟法测定,甲霜灵及甲霜灵锰锌对病原菌有很强的抑制作用。病原种鉴定正在进行。

Abstract:

Pathogeny isolation and back-inoculation were conducted for the Gingko biloba wilt occuring in the nursery.Gingko biloba wilt is found to be caused by Phytophthora sp., and harms the tender stems and leaves of nursery stock,but the roots and the individuals of perennial plants aren't harmed.The diseased leaves look like being scalded by boiling water.The diseased stems become black and the leaves on it wilt when a black spot has circled the stems.The pathogen colony on the PSA is white,villus shape and the sporangia and chlamydospores are abundant at 28℃ for 7 days.Sex organs are not found in culture medium.The favour temperature of the pathogen growth is 24℃~32℃.Inoculated with the pathogen,the wounded leaves and tender stems are infected seriously, but the healthy ones are lightly infected or can't be infected.Gingko biloba wilt in the field appears in early May,and goes to peak in 3 to 5 days,then stops in late May,and never appears again in the same year.The rate of infection is 10% to 20%.The infection center in the field is noticeable.Metalaxyl and Metalaxy1-MZ show strong restrain to the pathogen growth in the culture media containing and paper-disc containing.The species distinguish of the pathogen is going on.