Keith L, Sugiyama L, Strauss A, Kai R, Zee F, Hamasaki R, Yamasaki M, Nakamoto S
USDA-ARS, Hilo, HI.
University of Hawaii, Manoa.
Plant Dis. 2008 Nov;92(11):1590. doi: 10.1094/PDIS-92-11-1590A.
Blueberries (Vaccinium corymbosum L.) are a potential high-value, niche market crop for Hawaii. In May of 2007, rust-like symptoms were observed on multiple blueberry plants in a private nursery in Waimea, HI. In September of 2007, a similar leaf rust was observed on one bush of V. corymbosum cv. Sharpblue in the corner of a 36.6 × 9.1-m experimental plot at Mealani Research Station in Waimea. Within a month, rust was observed throughout the plot on 'Biloxi', 'Emerald', 'Jewel', 'Misty', 'Sapphire', and 'Sharpblue'. Preliminary field observations suggest that 'Sharpblue' and 'Sapphire' are highly susceptible to the rust and 'Biloxi' shows some tolerance. Leaf lesions began as approximately 1-mm chlorotic flecks that expanded and developed into reddish brown, necrotic spots with a chlorotic halo. New lesions and uredinia kept appearing over the course of 4 months. Defoliation occurred on plants where infection was severe. Yellowish orange pustules containing urediniospores first appeared on the abaxial side of older leaves and later appeared on new leaves. Urediniospores were elliptical to obovate (19.4 to 24.8 × 15.2 to 19.8 μm) with a thick, slightly roughened wall and a well-developed pore. Urediniospore morphology and dimensions were consistent with the description of Pucciniastrum vaccinii (G. Wint.) (1). A pathogenicity test was conducted with two 18-month-old 'Sharpblue' plants. Fully expanded leaves were sprayed with freshly collected urediniospores (3.8 × 10 spores per ml) suspended in a 0.05% solution of Tween 20 in water. The control plant was sprayed with sterile distilled water (SDW). Plants were covered with plastic bags for 48 h and held in a growth chamber at 20 to 22°C under continuous fluorescent lighting. The plastic bags were then removed and the plants were maintained in the growth chamber. Yellowish orange pustules that were identical to the original symptoms developed on 100% of inoculated leaves after 10 days. The plant inoculated with SDW remained symptomless. While leaf rust caused by P. vaccinii has been reported on Ohelo berry (V. reticulatum) (2), it has not been reported on V. corymbosum in Hawaii. To our knowledge, this is the first report of P. vaccinii on blueberry plants in Hawaii. This rust disease may pose a threat to the potential blueberry industry in Hawaii. References: (1) P. R. Bristow and A. W. Stretch. Page 20 in: Compendium of Blueberry and Cranberry Diseases. F. L. Caruso and D. C. Ramsdell, eds. The American Phytopathological Society, St. Paul, MN, 1995. (2) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA, 2008.
蓝莓（Vaccinium corymbosum L.）是夏威夷一种具有潜在高价值的小众市场作物。2007年5月，在夏威夷州威美亚的一家私人苗圃中，多株蓝莓植株上出现了类似锈病的症状。2007年9月，在威美亚米拉尼研究站一块36.6×9.1米试验地角落的一株夏普蓝品种（V. corymbosum cv. Sharpblue）蓝莓灌木丛上，发现了类似的叶锈病。在一个月内，试验地内的‘比洛克西’‘翡翠’‘宝石’‘薄雾’‘蓝宝石’和‘夏普蓝’植株上均发现了锈病。初步田间观察表明，‘夏普蓝’和‘蓝宝石’对锈病高度敏感，‘比洛克西’表现出一定的耐受性。叶片病斑最初为约1毫米的褪绿斑点，随后扩大并发展为带褪绿晕圈的红棕色坏死斑。在4个月的时间里，新的病斑和夏孢子堆不断出现。感染严重的植株出现落叶。含夏孢子的橙黄色脓疱最初出现在老叶背面，随后出现在新叶上。夏孢子椭圆形至倒卵形（19.4至24.8×15.2至19.8微米），壁厚，略有粗糙，具明显的孔。夏孢子形态和尺寸与vaccinii柄锈菌（G. Wint.）的描述一致（1）。对两株18个月大的‘夏普蓝’植株进行了致病性测试。用新鲜采集的夏孢子（每毫升3.8×10个孢子）悬浮于含0.05%吐温20的水溶液中，对充分展开的叶片进行喷雾。对照植株喷施无菌蒸馏水（SDW）。植株用塑料袋覆盖48小时，然后置于生长室，温度为20至22°C，持续荧光光照。之后取下塑料袋，植株继续置于生长室。10天后，接种叶片上100%出现了与最初症状相同的橙黄色脓疱。接种SDW的植株无症状。虽然在奥黑洛莓（V. reticulatum）上曾报道过由vaccinii柄锈菌引起的叶锈病（2），但在夏威夷的V. corymbosum上尚未见报道。据我们所知，这是夏威夷蓝莓植株上首次报道vaccinii柄锈菌。这种锈病可能对夏威夷潜在的蓝莓产业构成威胁。参考文献：（1）P. R. 布里斯托和A. W. 斯特雷奇。载于：《蓝莓和蔓越莓病害汇编》第20页。F. L. 卡鲁索和D. C. 拉姆齐德尔编。美国植物病理学会，明尼苏达州圣保罗，1995年。（2）D. F. 法尔等人。真菌数据库。系统植物学和真菌学实验室。在线出版物。美国农业部农业研究局，2008年。
