Neopestalotiopsis eucalypti,a causal agent of grapevine shoot rot in cutting nurseries in China

Grapevine (Vitis vinifera L.) is an economically important fruit crop in the world, and China ranks first in the production of grapes with approximately 15% of the world's total yield. However, diseases that cause the death of grapevine shoots pose a severe threat to the production of grapes. In this study, the fungus Neopestalotiopsis eucalypti was identified as a causal pathogen of grapevine shoot rot based on the morphology of conidia and a phylogenetic analysis. The phylogenetic analysis was performed with three isolates based on the combined sequence of internal transcribed spacer (ITS) region of ribosomal DNA, part of the translation elongation factor 1-alpha (Tef) and the β-tubulin (Tub2) genes. The three isolates were all identified as N. eucalypti. Pathogenicity tests of the three fungal isolates were conducted on grapevines shoots in vitro and in vivo. The results showed that all three fungal isolates caused severe rot lesions on the inoculated grapevine shoots, and N. eucalypti was re-isolated from the inoculated grapevine shoots. Therefore, N. eucalypti was confirmed as a causal agent of the grapevine shoot rot. This is the first report of N. eucalypti causing grapevine shoot disease in China.     

桉树云斑天牛大尺度范围的危害特征分析

【目的】研究桉树云斑天牛大尺度范围的危害特征，为进一步科学有效制定云斑天牛防控措施提供参考依据。【方法】2017年7-9月系统调查了重庆市19个区县102个桉树林云斑天牛危害样点，通过解剖受害树干系统分析云斑天牛的危害特征及其相关影响因素。在此基础上，利用主成分分析法研究桉树云斑天牛致灾的关键因素，并评估各调查点桉树云斑天牛危害的风险水平。【结果】重庆桉树林调查点云斑天牛轻度、中度及重度危害的受害株率分别为3.4%，15.8%和55.3%，平均值达到40.2%，为重度且成灾水平。危害特征分析结果表明，当年有效刻槽数（虫口密度）与无效刻槽数在云斑天牛重度危害下存在显著相关性（P<0.05）；无论是同一树高不同危害程度间还是同一危害程度不同树高间，当年株均无效刻槽数均有明显的规律变化，且出现了显著性差异（P<0.05）。当年虫口密度在轻度、中度及重度危害下均以树高区间≤1.0 m为主，且≤1.0 m显著多于3.1 m以上（P<0.05）；同一树高区间虫口密度均为重度危害显著大于轻度和中度危害（P<0.05），轻度和中度危害间差异不显著（P>0.05）。在轻度和中度危害下，受害株率与虫口密度的关系模型更适合用三次函数方程表示，但多数差异不显著（P>0.05）；在重度及总危害条件下，树高≤1.0 m及总高度上受害株率与虫口密度的关系可用幂函数表示，其他高度受害株率与虫口密度的关系符合三次函数关系，且多数差异显著（P<0.05）。相关性和主成分分析结果表明，受害株率与虫口密度均受到林分类型和桉树品种的极显著影响（P<0.01）。基于调查点各因素得分的PCA排序表明，无危害和轻度危害样点的生境条件及危害特征相似性高，重度危害则差异很大，而中度危害居于前2类中间，呈明显的过渡特征。铜梁、璧山、丰都、渝北、垫江、长寿和永川等区县具有高风险危害中心。【结论】重庆各调查样点桉树云斑天牛种群数量呈上升趋势，危害程度总体属于重度且成灾水平；不同危害程度下受害株率与虫口密度的关系可用三次函数或幂函数表示；重度危害下各样点桉树云斑天牛的危害特征与生境条件差异很大，林分类型和桉树品种是云斑天牛致灾的关键因素。     

桉树紫斑病病原菌探讨

桉树紫斑病的原病菌，据以往报道，我国仅有桉壳针孢（Septoria mortarlensis Penz.et Sacc)一个种。本文作者基于滇中、滇西的赤桉和大叶桉紫斑病标本，根据病原菌之产孢方式为全壁芽生环痕式hb-ann)，孢子梗顶部具1－3个环痕，分生孢子浅褐色，表面多有小粒状突起显粗糙等特征，确认其并非桉壳针则是桉壳褐针孢（Phaeoseptoria eucalypti Hansf.)该病原在我国属首次报道。文中讨论了上述两个种形态特点的主要差异。     

Ralstonia solanacearum decreases volumetric growth of trees and yield of kraft cellulose of Eucalyptus spp.

Ralstonia solanacearum is currently one of the most important plant pathogenic bacteria worldwide, with a wide geographical distribution and host diversity. The pathogen infects more than 200 plant species belonging to approximately 50 plant families, including Eucalyptus spp. Although, high losses have been reported in nurseries, little is known on the negative impact of the disease in the field. In this study, we evaluated the incidence of R. solanacearum and its effect on volumetric growth and cellulose yield of discoloured wood chips obtained from infected trees of one clone of Eucalyptus urophylla and two hybrid clones of Eucalyptus urophylla × E. grandis. The average incidence of bacterial wilt ranged between 60.6% and 72.4%. Volumetric growth of infected trees disease decreased 78.6% and 81.7% at 18 and 30 months, respectively. The pulp screen yield of three clones decreased between 3.2 and 6.4%, with an average 4.3%. The results of this work provide useful information on the losses of volumetric growth and pulp yield of eucalypt caused by R. solanacearum.