Pretorius Z A, Boshoff W H P, Kema G H J
Department of Plant Pathology, University of the Free State, Bloemfontein 9300, South Africa.
ARC-Small Grain Institute, Private Bag X29, Bethlehem 9700, South Africa.
Plant Dis. 1997 Apr;81(4):424. doi: 10.1094/PDIS.1997.81.4.424D.
During August 1996, stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici, was observed for the first time on bread wheat (Triticum aestivum) in the Western Cape, South Africa. Ensuing surveys during the growing season indicated that stripe rust occurred throughout most of the wheat-producing areas in the winter rainfall regions of the Northern, Western, and Eastern Cape provinces. The disease was also observed on irrigated wheat in the summer rainfall area south of Kimberley. Stripe rust was most severe in the Western Cape, where prolonged cool and wet conditions favored epidemic development and necessitated extensive and often repeated applications of triazole fungicides. Due to spike infection and destruction of foliage, significant losses in grain quantity and quality occurred in certain fields. Avirulence/virulence characteristics of 32 stripe rust isolates, collected from commercial wheat fields, trap nurseries, and triticale, were determined on 17 standard differential wheat lines and seven supplementary testers supplied by C. R. Wellings, Plant Breeding Institute, Cobbitty, Australia. All isolates were representative of one pathotype, characterized by avirulence to Chinese 166 (Yr1), Vilmorin 23 (Yr3), Moro (Yr10), Strubes Dickkopf, Suwon 92/Omar, Clement (Yr2,9), Triticum aestivum subsp. spelta var. album (Yr5), Hybrid 46 (Yr4), Reichersberg 42 (Yr7), Heines Peko (Yr2,6), Nord Desprez (Yr3), Carstens V, Spaldings Prolific, Heines VII (Yr2), Federation*4/Kavkaz (Yr9), and Avocet-S/Yr15, and by virulence to Kalyansona (Yr2), Heines Kolben (Yr2,6), Lee (Yr7), Compair (Yr8), and Federation 1221. Cultivars Trident (Yr17), Avocet-R (YrA), and Selkirk (YrSk) appeared heterogeneous for stripe rust reaction. The pathotype resembled race 6E16, previously detected in East and North Africa, the Middle East, and western Asia. Pathotype identity was confirmed at IPO-DLO, Wageningen, using one South African isolate of P. striiformis f. sp. tritici. In view of the rapid dispersal of the pathogen during 1996, susceptibility of several high-yielding cultivars, and favorable climatic conditions in many wheat-growing areas, stripe rust is considered potentially damaging to South African wheat production. Field observations and seedling tests have shown, however, that certain cultivars are resistant to the introduced pathotype. At present the genetic basis of this resistance is largely unknown.
1996年8月，南非西开普省的面包小麦（普通小麦）上首次发现了由条形柄锈菌小麦专化型（Puccinia striiformis f. sp. tritici）引起的条（黄）锈病。在生长季节随后进行的调查表明，条锈病发生在北开普省、西开普省和东开普省冬季降雨区的大部分小麦产区。在金伯利以南夏季降雨区的灌溉小麦上也发现了这种病害。条锈病在西开普省最为严重，那里长期凉爽潮湿的条件有利于病害流行，因此需要大量且经常重复施用三唑类杀菌剂。由于穗部感染和叶片受损，某些田块的谷物产量和质量遭受了重大损失。从商业麦田、诱捕苗圃和小黑麦上采集了32个条锈菌分离株，在由澳大利亚科比特蒂植物育种研究所的C. R. 韦林斯提供的17个标准鉴别小麦品系和7个补充测试品种上测定了其无毒/毒性特征。所有分离株均代表一种致病型，其特征是对中国166（Yr1）、维尔莫林23（Yr3）、莫罗（Yr10）、施特鲁贝·迪克科普夫、水原92/奥马尔、克莱门特（Yr2,9）、普通小麦亚种斯佩尔特变种白粒（Yr5）、杂交46（Yr4）、赖歇斯贝格42（Yr7）、海涅斯佩科（Yr2,6）、诺德·德普雷（Yr3）、卡斯滕斯V、斯波尔丁斯高产、海涅斯七世（Yr2）、联邦*4/高加索（Yr9）和阿沃塞特-S/Yr15无毒，而对卡利安索纳（Yr2）、海涅斯科尔本（Yr2,6）、李（Yr7）、康佩尔（Yr8）和联邦1221有毒。品种三叉戟（Yr17）、阿沃塞特-R（YrA）和塞尔柯克（YrSk）在条锈病反应上表现出异质性。该致病型类似于先前在东非、北非、中东和西亚检测到的6E16小种。利用南非的一个条形柄锈菌小麦专化型分离株，在瓦赫宁根的国际植物病理研究所确认了致病型的一致性。鉴于1996年病原体的迅速传播、几个高产品种的易感性以及许多小麦种植区有利的气候条件，条锈病被认为可能对南非的小麦生产造成损害。然而，田间观察和幼苗试验表明，某些品种对引入的致病型具有抗性。目前，这种抗性的遗传基础在很大程度上尚不清楚。
