Draper M A, Secor G A, Gudmestad N C
Department of Plant Pathology, North Dakota State University, Fargo 58105.
Plant Dis. 1997 Jun;81(6):693. doi: 10.1094/PDIS.1997.81.6.693D.
Powdery scab is a serious disease of potatoes (Solanum tuberosum L.) that can cause extensive surface defects on susceptible potato cultivars. The pathogen, Spongospora subterranea (Wallr.) Lagerh. f. sp. subterranea J. A. Tomlinson, is an important concern in seed potato production because current seed certification standards in North Dakota have a zero tolerance for this pathogen. Powdery scab had not previously been identified in North Dakota. Until recently this disease was not thought to be present in U.S. commercial potato-producing areas. Powdery scab has now been shown to be more widely distributed than previously thought (1), having been identified in several locations in eastern and western North America. However, environmental conditions in North Dakota, including high soil pH, low rainfall, and high temperatures, are not considered favorable for powdery scab development. Diseased potatoes were found in a field from Griggs County, ND, in the fall of 1994 and characteristic cystosori were present in erumpent lesions on infected tubers. The field was an irrigated circle planted to three different cultivars. The cultivars Goldrush and Red Norland were symptomless, while cv. Red La-Soda was severely affected. Up to 30% of the tuber surfaces were diseased and disease incidence approached 25%. The infected crop was destroyed. Pathogenicity was confirmed by planting pieces of diseased tuber tissue adjacent to healthy seed pieces of Russet Burbank. Transmission of the obligate parasite occurred naturally by simulating conditions that were favorable for infection, acidic potting mix (Jiffy-Mix) maintained at a high water potential. Progeny plants were found to be infected on both tubers and roots after 60 days. Control plants that were not exposed to diseased tuber pieces were unaffected. North Dakota, a major seed-potato-producing state, ships seed to every other potato-producing area in the U.S. and much of Canada. Infected seed shipped to areas with a favorable environment for disease development may result in crops becoming diseased and unmarketable. The cooler temperatures and higher than normal rainfall during the 1992 to 1995 seasons may account for powdery scab development in North Dakota. Recent increases in irrigated agriculture and potato production in North Dakota could lead to the infestation of new areas, restricting the value of that land for potato production. Reference: (1) B. Christ et al. Am. Potato J. 65:583, 1988.
粉痂病是马铃薯（Solanum tuberosum L.）的一种严重病害，可导致易感马铃薯品种出现大面积的表面缺陷。病原菌为马铃薯粉痂菌（Spongospora subterranea (Wallr.) Lagerh. f. sp. subterranea J. A. Tomlinson），在种薯生产中是一个重要问题，因为北达科他州目前的种子认证标准对这种病原菌零容忍。此前北达科他州尚未发现粉痂病。直到最近，人们还认为这种病害在美国商业马铃薯产区并不存在。现已证明，粉痂病的分布范围比之前认为的更广（1），在北美东部和西部的多个地点都有发现。然而，北达科他州的环境条件，包括高土壤pH值、低降雨量和高温，被认为不利于粉痂病的发生发展。1994年秋季，在北达科他州格里格斯县的一块田地中发现了患病马铃薯，受感染块茎的破裂病斑上出现了典型的粉痂孢子堆。这块田地是一个灌溉圈，种植了三个不同的品种。“淘金者”和“红诺兰”品种无症状，而“红拉索达”品种则受到严重影响。高达30%的块茎表面患病，发病率接近25%。受感染的作物被销毁。通过将患病块茎组织块种植在“褐皮伯班克”健康种薯块旁边，证实了其致病性。通过模拟有利于感染的条件，即保持高水势的酸性盆栽混合料（Jiffy-Mix），专性寄生菌自然传播。60天后，发现后代植株的块茎和根系都受到了感染。未接触患病块茎块的对照植株未受影响。北达科他州是主要的种薯生产州，向美国其他马铃薯产区以及加拿大的大部分地区运送种薯。将受感染的种薯运往有利于病害发展的地区可能会导致作物染病而无法销售。1992年至1995年期间较为凉爽的气温和高于正常水平的降雨量可能是北达科他州出现粉痂病的原因。北达科他州近期灌溉农业和马铃薯生产的增加可能会导致新地区受到侵染，限制该土地用于马铃薯生产的价值。参考文献：（1）B. 克里斯等人，《美国马铃薯杂志》65:583，1988年。
