Lu X, Robertson A E, Byamukama E, Nutter F W
Department of Plant Pathology, Iowa State University, Ames, IO 50011, USA.
Phytopathology. 2010 Sep;100(9):931-40. doi: 10.1094/PHYTO-100-9-0931.
The prevalence of soybean fields with plants infected with Soybean mosaic virus (SMV) in Iowa is assumed to be random, because the primary source of the virus is SMV-infected seed. Data collected from 2,500 soybean fields sampled over a 3-year period as part of the Iowa Soybean Disease Survey (2005 to 2007) were used to evaluate this assumption. SMV was first detected in early June of each year but counties in which it was first detected varied among years. Prevalence at the county scale at end of season was 32.3, 27.3, and 89.9% in 2005, 2006, and 2007, respectively. End-of-season incidence of SMV within SMV-positive counties was 1.5 to 25.0, 1.7 to 24, and 1.8 to 58% in 2005, 2006, and 2007, respectively. The number of fields in which plants infected with SMV were detected increased at the linear rate of approximately one new field every 2 days in 2007, compared with one new field every 22 days (2005) and 21 days (2006), with coefficients of determination (R2) of 93.2 to 96.8% using the linear model. Weak spatial dependence for end-of-season SMV incidence was detected using Moran's Index, indicating that the risk for SMV incidence at the county scale within Iowa at the end of the growing season is not random.
爱荷华州大豆花叶病毒（SMV）感染植株的大豆田流行率被认为是随机的，因为该病毒的主要来源是感染SMV的种子。作为爱荷华州大豆病害调查（2005年至2007年）的一部分，在3年期间从2500个大豆田采集的数据用于评估这一假设。SMV每年6月初首次被检测到，但首次检测到它的县在不同年份有所不同。2005年、2006年和2007年季末县尺度的流行率分别为32.3%、27.3%和89.9%。2005年、2006年和2007年，SMV阳性县内季末SMV发病率分别为1.5%至25.0%、1.7%至24%和1.8%至58%。2007年，检测到感染SMV植株的田块数量以大约每2天新增一个田块的线性速率增加，相比之下，2005年是每22天新增一个田块，2006年是每21天新增一个田块，使用线性模型时决定系数（R2）为93.2%至96.8%。使用莫兰指数检测到季末SMV发病率存在弱空间依赖性，这表明生长季末爱荷华州内县尺度上SMV发病风险并非随机。
