Centre for Horticultural Science, Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Ecosciences Precinct, Dutton Park 4102, Queensland, Australia.
Centre for Horticultural Science, QAAFI, The University of Queensland, Queensland Bioscience Precinct, St. Lucia 4072, Queensland, Australia.
Phytopathology. 2020 Oct;110(10):1680-1692. doi: 10.1094/PHYTO-02-20-0047-R. Epub 2020 Aug 27.
Citrus black spot, caused by , is characterized by fruit blemishes and premature fruit drop, resulting in significant economic losses in summer rainfall areas. The pathogen forms both conidia and ascospores during its life cycle. However, the occurrence of these spores and their contributions to infection of fruit in field conditions are not well understood. Our research using direct leaf litter monitoring and volumetric spore trapping in Queensland orchards revealed that pseudothecia and ascospores in leaf litter as well as trapped ascospores had low abundance, while pycnidia and conidia were highly abundant. Both and endophytic spp. were identified, with being dominant. In replicated field trials, we determined that infection of Imperial mandarin fruit by occurred from fruit set until week 20 of fruit development, with the key infection events taking place between weeks 4 and 16 in Queensland subtropical conditions. These results demonstrate that protecting fruit during weeks 4 to 16 significantly reduced infection. We found no significant correlation between the disease incidence in fruit and conidial abundance in leaf litter or ascospore abundance measured by volumetric spore trapping. Therefore, it is suggested that inoculum sources in the tree canopy other than those detected by spore trapping and direct leaf litter monitoring may play a major role in the epidemiology of citrus black spot. Improved knowledge regarding epidemiology of and an understanding of propagules causing infection may aid in development of more effective disease management strategies.
柑橘黑斑病由引起，其特征是果实出现斑点和提前落果，在夏季多雨地区会造成重大经济损失。该病原体在其生命周期中形成分生孢子和子囊孢子。然而，这些孢子的发生及其对田间果实感染的贡献尚不清楚。我们在昆士兰州果园进行的直接叶凋落物监测和容积孢子捕捉研究表明，叶凋落物中的假囊壳和子囊孢子以及捕获的子囊孢子数量较少，而分生孢子数量较多。鉴定出假囊壳和内生，其中占优势。在重复的田间试验中，我们确定在果实发育的第 20 周之前，从果实设定开始，就已经发生了对帝王柑果实的感染，在昆士兰亚热带条件下，关键的感染事件发生在第 4 周到第 16 周之间。这些结果表明，在第 4 周到第 16 周期间保护果实可以显著减少的感染。我们发现，果实中的病害发生率与叶凋落物中的分生孢子数量或容积孢子捕捉测量的子囊孢子数量之间没有显著相关性。因此，建议树冠中的接种体来源可能除了通过孢子捕捉和直接叶凋落物监测检测到的来源之外，在柑橘黑斑病的流行病学中可能发挥主要作用。更好地了解和理解引起感染的繁殖体可能有助于制定更有效的疾病管理策略。
