Goates Blair J, Peterson Gary L, Bowden Robert L, Maddux Larry D
USDA-ARS, Aberdeen, ID.
USDA-ARS, Frederick, MD.
Plant Dis. 2011 Apr;95(4):478-484. doi: 10.1094/PDIS-10-10-0732.
Dwarf bunt caused by Tilletia contraversa is a disease of winter wheat that has a limited geographic distribution due to specific winter climate requirements. The pathogen is listed as a quarantine organism by several countries that may have wheat production areas with inadequate or marginal climate for the disease-in particular the People's Republic of China. Field experiments were conducted in the United States in an area of Kansas that is a climatic analog to the northern winter wheat areas of China to evaluate the risk of disease introduction into such areas. The soil surface of four replicate 2.8 × 9.75 m plots, planted with a highly susceptible cultivar, was inoculated with six teliospore concentrations ranging from 0.88 to 88,400 teliospores/cm. A single initial inoculation was done in each of three nurseries planted during separate seasons followed by examination for disease for 4 to 6 years afterward. Any diseased spikes produced were crushed and returned to the plots where they were produced. One nursery had no disease during all six seasons. In two nurseries, the disease was induced at trace levels at the three highest inoculation rates. Disease carryover to the second year occurred during one year in one nursery in plots at the highest inoculation rate, but no disease occurred the following three seasons. A duplicate nursery planted in a disease conducive area in Utah demonstrated that the highest rate of inoculum used in the experiments was sufficient to cause almost 100% infection. This study demonstrated that in an area with marginal climatic conditions it was possible to induce transient trace levels of dwarf bunt, but the disease was not established even with a highly susceptible cultivar and high levels of inoculum. Our results support the conclusions of the 1999 Agreement on U.S.-China Agricultural Cooperation which set a tolerance for teliospores in grain, and supports the Risk Assessment Model for Importation of United States Milling Wheat Containing T. contraversa.
由矮腥黑粉菌（Tilletia contraversa）引起的矮腥黑穗病是冬小麦的一种病害，由于对冬季气候有特定要求，其地理分布有限。该病原菌被多个国家列为检疫性生物，这些国家可能有小麦产区，其气候条件不利于或勉强适宜该病发生——尤其是中华人民共和国。在美国堪萨斯州一个气候与中国北方冬小麦产区相似的地区进行了田间试验，以评估该病传入此类地区的风险。在四个重复的2.8×9.75米地块上种植了高感品种，土壤表面接种了六种冬孢子浓度，范围从0.88至88400个冬孢子/平方厘米。在三个不同季节种植的苗圃中，每个苗圃都进行了一次初始接种，之后连续4至6年检查病害情况。产生的任何病穗都被碾碎并返还至其产生的地块。在所有六个季节中，有一个苗圃未发病。在两个苗圃中，在三个最高接种率下诱发出了痕量水平的病害。在一个苗圃中，最高接种率的地块在一年中出现了病害越冬至次年的情况，但随后三个季节未发病。在犹他州一个病害易发生地区种植的一个重复苗圃表明，试验中使用的最高接种量足以导致近100%的感染率。本研究表明，在气候条件勉强适宜的地区，有可能诱发出痕量水平的短暂矮腥黑穗病，但即使使用高感品种和高接种量，该病也未能定殖。我们的结果支持了1999年《中美农业合作协议》的结论，该协议设定了谷物中冬孢子的容忍度，并支持了对含有矮腥黑粉菌的美国制粉小麦进口的风险评估模型。
