Worldwide, tree species sometimes fall victim to epidemics of microbial pathogens, usually spread by sap-sucking insects. One such example is the recent devastation of cabbage trees (Cordyline australis) in New Zealand by a damaging phytoplasm (‘Candidatus Phytoplasma australiense’). Cabbage trees are among New Zealand’s most emblematic plant species, playing an iconic role in many landscapes. They were first reported dying in Northland in 1987, of a condition given the name ‘sudden decline’. The small hemipteran Zeoliarus oppositus is now known to be the main vector spreading the disease. Here I document the establishment and spread of the disease throughout the North Island and upper South Island of New Zealand over a 24-year period. In this study, some 31,000 living and dead cabbage trees were counted on roadsides in the North Island and northern South Island, in 1990, 1995, 2000, 2006, and between 2012 and 2014. Infected trees lost their leaves, leaving dead white trunks standing until they rotted away over two or three years. Large, mature trees were particularly susceptible to infection and were all but wiped out in many parts of the North Island districts of Northland, Bay of Plenty, the Waikato, King Country, and Hawkes Bay, transforming some landscapes. The South Island was almost free of the disease, with the exception of Marlborough and Nelson. The percentage of dead trees peaked between 1990 and 2006 but declined by 2012–2014 as susceptible large trees became rarer. Differences in the insect vector’s regional abundance are thought to account for the national pattern of deaths.

在世界范围内，树木有时是微生物病原体流行病的受害者，这些病原体通常是通过吸吮树液的昆虫传播的。一个这样的例子是最近在新西兰的一种有害的植物质（' Candidatus Phytoplasma australiense'）毁坏了甘蓝树（Cordyline australis）。白菜树是新西兰最具代表性的植物之一，在许多景观中都起着标志性作用。据报道，他们于1987年在北国死亡，当时的状况被称为“突然下降”。小的半翅目Zeoliarus oppositus现在已知是传播这种疾病的主要媒介。在这里，我记录了该病在24年内在新西兰北岛和南岛上部的建立和传播。在这项研究中，分别在1990年，1995年，2000年，2006年以及2012年至2014年之间，在北岛和南岛北部的路边计数了约31,000棵活的和枯萎的白菜树。受感染的树失去了叶子，留下了枯白的树干直到他们腐烂了两三年。大而成熟的树木特别容易受到感染，并且在北岛的北岛地区，丰盛湾，怀卡托，国王乡村和霍克斯湾的许多地区几乎全部被消灭，从而改变了一些景观。除了马尔伯勒和纳尔逊，南岛几乎没有这种疾病。死树的百分比在1990年至2006年间达到峰值，但由于易感大树变得稀少，到2012-2014年间下降了。昆虫媒介区域丰度的差异被认为是造成死亡的国家模式。