South Africa is the largest producer of macadamias in the world, producing an estimated 61,288 tons nut-in-shell in 2022. In order to ensure the sustainability of the industry, it is important that research focuses on the control and eradication of economically important pests and diseases. Macadamia trees in the Mpumalanga Lowveld of South Africa have for some time shown severe chlorosis, which coincides with a significant drop in production, with losses of up to 60% being recorded. The disease has since been coined Macadamia Chlorosis Disease (MCD). In an attempt to determine whether MCD may be associated with a virus, high-throughput Illumina sequencing was performed on RNA extracted from both diseased and healthy trees collected from farms in Mpumalanga. Subsequent data analyses could not link a specific virus to MCD, however, reads spanning the full genome of a novel virus belonging to the Orthotospovirus genus were obtained. An RT-PCR assay was optimized for the detection of this virus and subsequent surveys linked the virus to ringspot symptoms which are commonly observed on different macadamia cultivars. The virus has to date been identified from orchards in Mpumalanga, Limpopo and KwaZulu-Natal. Other viruses described in the genus are known to cause severe crop losses and it is therefore important that the virus, provisionally named macadamia ringspot-associated virus (MRSV), be further studied to determine whether association with this virus can lead to yield losses, and whether appropriate control strategies must be implemented to prevent the spread of MRSV.

南非是世界上最大的澳洲坚果生产国，预计到 2022 年将生产 61,288 吨带壳坚果。为了确保该行业的可持续性，研究重点是控制和消灭具有重要经济意义的害虫非常重要和疾病。一段时间以来，南非普马兰加省低地草原的澳洲坚果树出现了严重的失绿现象，同时产量也大幅下降，损失高达 60%。此后，这种疾病被称为澳洲坚果黄化病（MCD）。为了确定 MCD 是否与病毒有关，我们对从普马兰加省农场收集的患病树木和健康树木中提取的 RNA 进行了高通量 Illumina 测序。随后的数据分析无法将特定病毒与 MCD 联系起来，但是获得了属于正孢病毒属的新型病毒的完整基因组的读数。RT-PCR 检测针对该病毒的检测进行了优化，随后的调查将该病毒与不同澳洲坚果品种上常见的环斑症状联系起来。迄今为止，已在姆普马兰加省、林波波省和夸祖鲁-纳塔尔省的果园中发现了该病毒。已知该属中描述的其他病毒会导致严重的作物损失，因此，进一步研究该病毒（暂时命名为澳洲坚果环斑相关病毒（MRSV））以确定与该病毒的关联是否会导致产量损失非常重要，并且是否必须实施适当的控制策略来防止 MRSV 的传播。