Wunsch Anna O, Miranda Sazo Mario, van Zoeren Janet, Lamour Kurt H, Hurtado-Gonzales Oscar P, Khan Awais, Fuchs Marc
Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, USA.
Cornell Cooperative Extension Lake Ontario Fruit Program, Albion, NY 14411, USA.
Plants (Basel). 2024 Oct 14;13(20):2866. doi: 10.3390/plants13202866.
A sudden, unexplained decline and collapse of young apple trees on dwarfing and semi-dwarfing rootstocks has been reported across North America over the past decade. Although viruses have been detected in declining trees, no information is available on their potential causal role in the decline phenomenon. To this end, virus-inoculated apple trees were established in a high-density experimental orchard and monitored over five years. Tree decline was observed in year 4 (2022), resulting in 17% mortality, with declining trees exhibiting marked vascular tissue necrosis. However, none of the eight viruses and one viroid detected in the experimental orchard was significantly more prevalent in declining trees. Extreme temperature fluctuations in January 2022, followed by a severe water deficit in summer 2022, were recorded at the experimental orchard. Similar but distinct observations were made in a nearby commercial orchard with foliar nutrient imbalances documented in trees exhibiting symptoms of rapid decline. Together, our findings suggest that viruses are not primarily responsible for the rapid decline phenomenon and highlight the need for future work to investigate the roles of tree physiology and water stress in tree decline, as well as the potential efficacy of horticultural mitigation practices.
在过去十年中，北美各地均有报道称，矮化和半矮化砧木上的幼龄苹果树突然出现不明原因的衰退和死亡。尽管在衰退的树木中检测到了病毒，但关于它们在衰退现象中可能的因果作用尚无相关信息。为此，在一个高密度实验果园中种植了接种病毒的苹果树，并进行了为期五年的监测。在第4年（2022年）观察到树木衰退，死亡率达17%，衰退的树木表现出明显的维管组织坏死。然而，在实验果园中检测到的8种病毒和1种类病毒，在衰退的树木中均未显著更普遍。实验果园记录到，2022年1月温度剧烈波动，随后在2022年夏季出现严重缺水。在附近一个商业果园也有类似但不同的观察结果，表现出快速衰退症状的树木存在叶片营养失衡现象。我们的研究结果共同表明，病毒并非导致快速衰退现象的主要原因，并强调未来有必要开展工作，研究树木生理学和水分胁迫在树木衰退中的作用，以及园艺缓解措施的潜在效果。
