College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing Agricultural University, Nanjing 210095, China.
Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Nanjing 210014, China.
Plant Dis. 2018 Dec;102(12):2511-2518. doi: 10.1094/PDIS-02-18-0243-RE. Epub 2018 Oct 15.
Peach (Prunus persica (L.) Batsch) is produced locally in Yangshan, Wuxi City, China. In recent years, a widespread shoot blight has been observed in many peach orchards of Yangshan that kills the twigs and results in high losses in fruit production. Disease incidences ranged from 10 to 20% in the affected orchards and, in extreme cases, 40% of the trees were affected. Shoot blight of peach is caused by a fungus, previously identified as Phomopsis amygdali. Between 2014 and 2015, samples were collected four times from three peach orchards located in Yangshan to understand the etiology of shoot blight. Interestingly, two types of shoot blight symptoms were observed: one characterized by necrotic lesions with rings and one without rings. Based on conidial morphology, cultural characteristics, and analysis of nucleotide sequences of three genomic regions (the internal transcribed spacer region, a partial sequence of the β-tubulin gene, and the translation elongation factor 1-α), isolates were identified as P. amygdali and Botryosphaeria dothidea. Remarkably, most of the P. amygdali isolates were recovered from twigs showing necrotic lesions without rings. In contrast, most of the B. dothidea isolates were recovered from twigs with rings in the necrotic lesions. Correlations among pathogens, sampling regions, and disease symptoms were noted, and growth rates of these pathogens were characterized. Pathogenicity tests showed that B. dothidea isolates could induce necrotic lesions with rings but P. amygdali isolates could only induce necrotic lesions. Moreover, the B. dothidea isolates exhibited higher levels of virulence than P. amygdali isolates on the peach twig. Additionally, high frequencies of detection of both P. amygdali and B. dothidea from buds indicated that buds may be the primary site of fungal invasion. Cankers and necrotic twigs may also serve as infection courts. Our results suggest that B. dothidea and P. amygdali are the common causal agents of peach shoot blight in Yangshan, China. This finding provides a basis for the development of effective management strategies.
桃（Prunus persica (L.) Batsch）在中国无锡阳山镇本地生产。近年来，阳山许多桃园普遍发生枝枯病，导致嫩枝死亡，果实产量损失严重。受影响果园的发病率在 10%至 20%之间，在极端情况下，有 40%的树木受到影响。桃枝枯病是由一种真菌引起的，以前被鉴定为李球腔菌。2014 年至 2015 年，从位于阳山的三个桃园采集了四次样本，以了解枝枯病的病因。有趣的是，观察到两种类型的枝枯病症状：一种特征为坏死环斑，另一种无环斑。根据分生孢子形态、培养特性以及三个基因组区域（内部转录间隔区、β-微管蛋白基因部分序列和翻译延伸因子 1-α）的核苷酸序列分析，分离物被鉴定为李球腔菌和多主枝孢菌。值得注意的是，大多数李球腔菌分离物是从无环斑坏死斑的嫩枝上回收的。相比之下，大多数多主枝孢菌分离物是从坏死斑有环的嫩枝上回收的。注意到病原体、采样区域和疾病症状之间的相关性，并对这些病原体的生长率进行了特征描述。致病性试验表明，多主枝孢菌分离物可引起有环斑的坏死斑，但李球腔菌分离物只能引起坏死斑。此外，多主枝孢菌分离物在桃嫩枝上的毒力水平高于李球腔菌分离物。此外，从芽中检测到李球腔菌和多主枝孢菌的高频率表明芽可能是真菌入侵的主要部位。溃疡和坏死嫩枝也可能成为感染法庭。我们的研究结果表明，多主枝孢菌和李球腔菌是中国阳山桃枝枯病的常见致病因子。这一发现为制定有效的管理策略提供了依据。
