Emmitt R S, Stevenson K L, Brenneman T B, Buck J W
Department of Plant Pathology, University of Georgia, Griffin Campus, Griffin 30223.
Department of Plant Pathology, University of Georgia, Tifton Campus, Tifton 31793.
Plant Dis. 2016 Jan;100(1):188-191. doi: 10.1094/PDIS-06-15-0648-RE. Epub 2015 Nov 11.
Daylily (Hemerocallis spp.) is a popular herbaceous perennial plant and was considered to be relatively disease free until 2000, when daylily rust, caused by Puccinia hemerocallidis, was first detected in the United States. Management of daylily rust in nurseries is dependent on the use of fungicides, which are typically applied to the foliage of large blocks of plants at 21- or 28-day intervals. The objectives of this study were to determine the most effective fungicides or fungicide combinations and application intervals for managing daylily rust in the field. Foliar sprays of azoxystrobin alone at 14-, 21-, or 28-day intervals, combinations of azoxystrobin + propiconazole, azoxystrobin + chlorothalonil, propiconazole + chlorothalonil, and chlorothalonil + thiophanate-methyl applied at intervals of 21or 28 days, and a nontreated control were evaluated under high disease pressure, at three locations in Griffin, GA in 2014. In all three fields, all treatments that included azoxystrobin were effective at reducing area under the disease progress curve (AUDPC) compared with the nontreated control. At two of the three locations, azoxystrobin applied at 14-day intervals had significantly lower AUDPC than when applied at 21- or 28-day intervals. The addition of propiconazole or chlorothalonil to azoxystrobin did not improve rust control. Disease ratings for propiconazole + chlorothalonil and thiophanate-methyl + chlorothalonil applied at 21- or 28-day intervals did not differ from the untreated control. The 21-day treatments resulted in significantly lower disease than 28-day treatments (all fungicides) in the middle and end of the season. Elimination of less efficacious active ingredients and unnecessary applications can help growers maximize profitability by reducing expenses as well as simplifying fungicide inventory and storage.
萱草（萱草属）是一种广受欢迎的多年生草本植物，在2000年之前被认为相对无病害，当时由萱草柄锈菌引起的萱草锈病首次在美国被发现。苗圃中萱草锈病的防治依赖于使用杀菌剂，通常每隔21天或28天对大片植株的叶片进行喷施。本研究的目的是确定在田间防治萱草锈病最有效的杀菌剂或杀菌剂组合以及施药间隔。2014年在佐治亚州格里芬的三个地点，在高病害压力下，对单独每隔14天、21天或28天喷施嘧菌酯，嘧菌酯+丙环唑、嘧菌酯+百菌清、丙环唑+百菌清以及百菌清+甲基托布津的组合，以及一个未处理对照进行了评估。在所有三个田块中，与未处理对照相比，所有包含嘧菌酯的处理在降低病害进展曲线下面积（AUDPC）方面都有效。在三个地点中的两个，每隔14天喷施嘧菌酯的AUDPC显著低于每隔21天或28天喷施时。在嘧菌酯中添加丙环唑或百菌清并没有改善锈病防治效果。每隔21天或28天喷施丙环唑+百菌清以及甲基托布津+百菌清的病害评级与未处理对照没有差异。在季节中期和末期，21天的处理（所有杀菌剂）导致的病害显著低于28天的处理。去除效果较差的活性成分和不必要的施药可以帮助种植者通过减少开支以及简化杀菌剂库存和储存来实现利润最大化。
