干旱区甜瓜霜霉病远距离传播空间结构的初步研究

 经过9年在塔里木盆地边缘干旱区对伽师县等3个相互隔离的甜瓜霜霉病流行系统的实地调查研究,提出了甜瓜霜霉病远距离传播的三级空间结构。一个甜瓜霜霉病流行系统单元是在一个绿洲内,围绕可提供初侵染病原的黄瓜温室区而形成的,其空间结构分为区系(包含若干种植区)、种植区(包含若干田块)和田块三级结构。伽师甜瓜霜霉病流行区系分为3个种植区,甜瓜霜霉病每年春季最先从位于种植一区发生霜霉病的黄瓜温室附近的甜瓜开始发生,之后甜瓜霜霉病由近向远逐步传播。种植二区和种植三区甜瓜霜霉病的初发病时间(初发病中心出现的时间)比种植一区的分别平均晚20和45d,发病中心与初菌源地的平均距离分别是56.4和106.5km,表明此地甜瓜霜霉病菌远距离传播经历了从种植一区到种植二区,再从种植二区到种植三区的传播过程。

Spatial structure of long-distance spread of Pseudoperonospora cubensis in muskmelon in arid area of Xinjiang

The epidemic of downy mildew in muskmelon was studied for 9 years in Jiashi,Arwat,and Kuqa counties,all located at the margin of Tarim Basin.Three-level spatial structure of long-distance spread of the disease was presented in this paper.An epidemic system in one oasis could be formed around a cucumber greenhouse area from which the primary inoculums was provided.The three-level spatial structure included epidemical region-system(consisted of some growing areas),growing area(consisted of some fields),and field.Jiashi epidemic system was divided into 3 growing areas.Downy mildew appeared first in the muskmelon fields near cucumber greenhouses in the first growing area every spring,and then spread outward further and further to other growing areas.The primary infection(the time when the primary infective points appeared in muskmelon fields)in the second growing area and the third growing area were 20 and 45 d later than that of the first growing area,respectively.The distances from the primary infective point in the second growing area and the third growing area to the infection source in the first growing area were 56.4 and 106.5 km respectively.Therefore,it was conformed that the disease sporangia were disseminated in the air to the second growing area from the first one and then dispersed to the third one in Jiashi.