Marshall David, Work Timothy T, Cavey Joseph F
USDA/ARS, Plant Science Research Unit, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616.
Department of Renewable Resources, University of Alberta, Alberta T6G-2H1, Canada.
Plant Dis. 2003 Aug;87(8):999-1003. doi: 10.1094/PDIS.2003.87.8.999.
Karnal bunt of wheat (caused by Tilletia indica) was first detected in the United States in Arizona in 1996. The seed lots of infected, spring-habit, durum wheat associated with the initial detection were traced to planted fields in California, Arizona, New Mexico, and Texas. However, in the summer of 1997, the disease appeared in unrelated, winter-habit, bread wheat located over 700 km from the nearest potentially contaminated wheat from 1996 (and destroyed prior to reinfection). Here, we examined potential invasion pathways of the fungus associated with the movement of wheat into the United States. We analyzed the USDA/APHIS Port Information Network (PIN) database from 1984 through 2000 to determine likely pathways of introduction based on where, when, and how the disease was intercepted coming into the United States. All interceptions were made on wheat transported from Mexico, with the majority (98.8%) being intercepted at land border crossings. Karnal bunt was not intercepted from any other country over the 17-year period analyzed. Most interceptions were on wheat found in automobiles, trucks, and railway cars. The majority of interceptions were made at Laredo, Brownsville, Eagle Pass, and El Paso, TX, and Nogales, AZ. Karnal bunt was intercepted in all 17 years; however, interceptions peaked in 1986 and 1987. Averaged over all years, more interceptions (19.2%) were made in the month of May than in any other month. Our results indicate that Karnal bunt has probably arrived in the United States on many occasions, at least since 1984. Because of the relatively unaggressive nature of the disease and its reliance on rather exacting weather conditions for infection, we surmised that it is possible this disease has a long period of latent survival between initial arrival and becoming a thriving, established disease.
小麦印度腥黑穗病（由印度腥黑粉菌引起）于1996年首次在美国亚利桑那州被发现。与最初发现相关的受感染的春性硬质小麦种子批次可追溯到加利福尼亚州、亚利桑那州、新墨西哥州和得克萨斯州的种植田。然而，在1997年夏天，该病出现在距离1996年最近的可能受污染小麦（且在再次感染前已被销毁）700多公里外的不相关的冬性面包小麦中。在此，我们研究了与小麦进入美国相关的真菌潜在入侵途径。我们分析了美国农业部动植物卫生检验局港口信息网络（PIN）1984年至2000年的数据库，以根据疾病在美国入境时的截获地点、时间和方式来确定可能的引入途径。所有截获均发生在从墨西哥运输的小麦上，大部分（98.8%）在陆地边境口岸被截获。在所分析的17年期间，未从任何其他国家截获到印度腥黑穗病。大多数截获发生在汽车、卡车和火车车厢中的小麦上。大部分截获发生在得克萨斯州的拉雷多、布朗斯维尔、伊格尔帕斯和埃尔帕索以及亚利桑那州的诺加利斯。17年中每年都截获到印度腥黑穗病；然而，截获量在1986年和1987年达到峰值。平均来看，5月份的截获量（19.2%）比其他任何月份都多。我们的结果表明，至少自1984年以来，印度腥黑穗病可能已多次传入美国。由于该病相对不具侵袭性且其感染依赖相当严格的天气条件，我们推测这种疾病在首次传入与成为一种猖獗的、已确立的病害之间可能有很长的潜伏存活期。
