Abstract Bull's eye rot is a postharvest disease of pome fruit caused by Neofabraea and Phlyctema species infecting the lenticels of fruit in the orchard with symptoms only becoming apparent after months in storage. Chemical control is a valuable method to manage postharvest diseases on pome fruit. In this study, the efficacy of the fungicides fludioxonil (299 mg/L) and pyrimethanil (500 mg/L) was tested on Phlyctema vagabunda Desmazieres, the prevalent bull's eye rot species in South Africa. Although both fungicides are registered on pome fruit against other fungal pathogens, neither are specifically registered against bull's eye rot in South Africa. Fruit trials involved curative dip, drench, and thermofogging applications of the fungicides on P. vagabunda inoculated 'Cripps Pink' and 'Fuji' apple fruit. Furthermore, the variation of pyrimethanil (500 and 1000 mg/L) sensitivity in planta in a dip application was evaluated on six P. vagabunda isolates from the Western Cape of South Africa. The effect of incubation time before treatment was tested in relation to the efficacy of the fungicides. Fludioxonil was highly effective in controlling P. vagabunda incidence as a dip application and moderately effective as a drench and thermofog application. Pyrimethanil had moderate efficacy on both cultivars as a thermofog application. The pyrimethanil dip application was ineffective in controlling disease incidence while the drench application had little efficacy on 'Fuji' apples and no efficacy on 'Cripps Pink' inoculated fruit. There was no variation in the efficacy of pyrimethanil to P. vagabunda isolates. Incubation time had a significant effect on pyrimethanil efficacy. Delaying pyrimethanil application after inoculation significantly decreased the efficacy of the fungicide in controlling P. vagabunda incidence. The longer inoculated fruit was incubated, the less susceptible the fungicide became. As a recommendation, further investigation into the ability of the fungicides to reduce P. vagabunda as a postharvest application should be conducted on pre-harvest, naturally infected, or conidial suspension inoculated fruit.

中文翻译：

---

氟啶虫胺和嘧霉胺在南非苹果收获后防治苹果上的应用

摘要 牛眼腐病是一种梨果果实采后病害，由新法氏和桃属种感染果园果实的皮孔引起，贮藏数月后症状才明显。化学防治是管理梨果采后病害的一种有价值的方法。在这项研究中，杀菌剂氟菌腈 (299 mg/L) 和嘧霉胺 (500 mg/L) 对南非流行的牛眼腐病菌 Phlyctema vagabunda Desmazieres 进行了测试。尽管这两种杀菌剂都在梨果果实上注册以对抗其他真菌病原体，但在南非都没有专门针对牛眼腐病进行注册。水果试验涉及杀菌剂在 P. vagabunda 接种的“Cripps Pink”和“Fuji”苹果果实上的治疗性浸渍、浸渍和热雾化应用。此外，对来自南非西开普省的 6 个 P. vagabunda 分离株，评估了浸涂中植物中嘧霉胺（500 和 1000 mg/L）敏感性的变化。测试处理前孵育时间的影响与杀真菌剂功效的关系。Fludioxonil 作为浸渍施用在控制迷走疟原虫发病率方面非常有效，作为淋涂和热雾施用的效果适中。嘧霉胺作为热雾应用对两个品种都有中等功效。嘧霉胺浸药对控制发病率无效，而浸药对'富士'苹果几乎没有效果，对'Cripps Pink'接种的果实没有效果。嘧霉胺对 P. vagabunda 分离株的效力没有变化。孵育时间对嘧霉胺功效有显着影响。接种后延迟嘧霉胺的施用会显着降低杀菌剂控制 P. vagabunda 发病率的功效。接种的果实孵化时间越长，杀菌剂变得越不敏感。作为建议，应在收获前、自然感染或分生孢子悬浮接种的果实上进一步研究杀菌剂在收获后应用时减少 P. vagabunda 的能力。