First report of Leveillula clavata causing powdery mildew on Euphorbia leucocephala from India

In December 2020, Euphorbia leucocephala plants exhibiting symptoms of powdery mildew were observed in the Botanical Garden of Tuljaram Chaturchand College, Baramati, Maharashtra, India. Based on morphological identification, DNA sequence analysis, and pathogenicity, the fungal pathogen of the disease was identified as Leveillula clavata. This is the first report of L. clavata on Euphorbia leucocephala from India and in general.     

Identification,pathogenicity and control of powdery mildew caused by Erysiphe elevata on Eucalyptus pellita in Sumatra,Indonesia

Powdery mildews are biotrophic ascomycetes that do not typically kill their hosts, but instead interfere with normal plant growth. In Indonesia, white powdery spots were observed forming on the upper part of fully developed leaves of Eucalyptus pellita planted in sand beds of a clonal nursery. Thus, this study aimed to identify the causal agent of eucalypt powdery mildew in Indonesia as well as to develop control strategies to better manage the disease. Pathogen identification was based on morphology, molecular characterization of DNA sequencing the ITS region and pathogenicity test. In addition, considering that some powdery mildews are inhibited by free moisture on leaves, efficacy of foliar watering was tested for disease control. Phylogenetic analyses showed that isolates collected from infected eucalypt plants grouped together with other sequences of the Erysiphe elevata clade with bootstrap support of 99%; a similar result was also confirmed by morphological observations. Pathogenicity of powdery mildew on eucalypt plants was confirmed through artificial inoculation, thus fulfilling the Koch's postulates. For disease control, foliar watering reduced the incidence of powdery mildew on mother plants. The reduction of the disease incidence began to be more evident at 2 weeks after trial establishment, and in the fourth week, the incidence was below 10% in all three treatments, while the control was above 20%. Therefore, we concluded that E. elevata is the causal agent of powdery mildew in Indonesia and that one application of foliar watering per week was enough to minimize the disease impact in the nursery.     

Erysiphe australiana: the cause of powdery mildew on Lagerstroemia speciosa in Brazil

Powdery mildew symptoms and signs were observed on seedlings of Lagerstroemia speciosa within an ornamental plant nursery in Viçosa, State of Minas Gerais, Brazil. Signs were most prominent as intense mycelial growth and sporulation on the shoots, new branches and leaves, which led to tissue necrosis. Based on morphological characteristics and phylogenetic analyses of ITS and 28S rDNA sequences, the powdery mildew pathogen of L. speciosa was identified as Erysiphe australiana, a well‐known powdery mildew pathogen infecting Lagerstroemia spp. worldwide. To our knowledge, this is the first report of E. australiana causing powdery mildew on L. speciosa in Brazil.     

First report of Erysiphe kenjiana causing powdery mildew of elm in Romania

Erysiphe kenjiana is an Asian fungus causing powdery mildew of Ulmus spp. In 2017, 10 years after its introduction in Europe, it was detected in Romania on Ulmus pumila, the Siberian elm, which is cultivated in urban environments as an ornamental and shade tree. The identification of the fungus was based on morphological characteristics and molecular data (rDNA internal transcribed spacer region). This is the first report of E. kenjiana in Romania, and only the third from a European country.     

冈尼桉引种繁殖试验

在我国中亚热带地区的湖南长沙开展了耐寒桉树冈尼桉的引种繁殖试验,初步研究结果表明：冈尼桉播种前应先用0.1%高锰酸钾浸种30 min,再播种于黄心土和沙土为3：1的基质中,萌发率为34.1%;冈尼桉实生苗不适应湖南长沙的夏季高温,引种第二年的夏季陆续死亡;冈尼桉种子经0.25%HgCl2消毒后,接种于MS＋BA0.2mg·L-1＋IBA 1 mg·L-1培养基中萌发率为28.8%,之后在MS＋BA 0.2 mg·L-1＋IBA 0.8 mg·L-1培养基中继代培养,生长良好。     

桉树与环境

本文收集了国内外的一些桉树与环境关系的研究资料。依据众多的研究成果分别从桉树与水分,桉树与土壤养分,桉树水土保持,桉树与其它生物的关系等方面论述了桉树与环境的相互关系;同时阐述笔者对云南发展桉树的看法：桉树每生产单位干物质所消耗的水分和养分少于其它植物,桉树对绿化荒山,保持水土,增加经济收入是有益的。因此,有计划、有步骤地继续在云南发展桉树实有必要。     

桉树体细胞培养研究进展

体细胞培养能获得稳定的遗传材料,还能通过变异获得抗性的育种材料。在现代科学技术的支撑下,通过体细胞培养来获得次生代谢物和进行细胞育种的技术不断完善。本文从桉树愈伤组织培养、原生质体培养、悬浮培养、体细胞胚胎发生和人工种子等五个方面对二十世纪八十年代以来桉树体细胞培养的研究进展进行了综述。     

桉树CTMP法制浆性能的研究

应用正交试验设计方法分析预浸时间、预浸温度、NaOH用量、Na2SO3用量对尾巨桉CTMP制浆性能的影响并选取最优方案,在此基础上,对4年生和6年生尾巨桉分别进行制浆抄纸,并对纸张物理性能进行测定。研究表明,适当的预浸时间、预浸温度、NaOH用量、Na2SO3用量可制得质量较好的CTMP。     

Erysiphe diffusa causing powdery mildew on Mimosa caesalpiniifolia in Brazil: A soya bean pathogen found on an important native Brazilian tree

Mimosa caesalpiniifolia: Fabaceae (sansão‐do‐campo or sabiá, in Brazil) is a small tree or shrub native to the Brazilian semi‐arid forest and widely used as a hedge plant in Brazil. Although of economic relevance, little is known of fungal pathogens infecting this plant. Recently, plants growing in an urban situation at Ouro Preto, and also on the roadside in Viçosa (state of Minas Gerais, Brazil), were found to be severely attacked by a powdery mildew which led to progressive leaf blight and serious defoliation. Based on morphology and molecular phylogenetic analysis of nuclear rDNA sequences, the fungus was identified as Erysiphe diffusa—a pathogen best known attacking soya bean, particularly in highland plantings.     

桉树水分胁迫研究进展

综述了桉树叶、根的形态性状、生理生化、分子遗传等方面与水分胁迫关系等研究成就,为研究桉树抗旱机理、抗旱育种提供参考。     

植物对白粉菌的亲和性研究进展

植物对白粉菌的亲和性是当前植物病理学研究的热点与难点之一。该研究在理论上为进一步了解活体寄生菌抑制植物防卫反应和利用植物活体营养的分子机制奠定了基础,在生产实践上,对于通过诱导植物对白粉菌感病基因发生突变或使基因沉默来培育植物抗白粉病新品种有重要意义。本文就细胞、生化以及分子水平上简要阐述了该方面的研究进展。     

桉树对种植地土壤质量的影响

从土壤的养分、水分、生物多样性以及生态稳定性4个方面论述了桉树人工林对其林地土壤质量造成的影响。据此提出今后发展桉树应开展的重点研究工作。     

不同桉树无性系造林对比试验

通过7个桉树无性系在3个不同立地条件的造林对比试验研究,结果表明:7个桉树无性系在本区表现良好,不同桉树无性系间在胸径、树高、蓄积量生长方面均存在显著差异;适宜本区发展的桉树无性系首选为尾赤桉201-2,其次为尾巨桉3229和尾圆桉184-1;海拔在300 m以下的适宜种尾赤桉201-2、尾圆桉184-1、尾巨桉3229等,海拔在300~460 m的适合种尾赤桉201-2和巨桉。     

桉树一次性授粉研究

以一次性授粉研究了细叶桉与粗皮桉等其他桉树花粉杂交情况,试验结果表明以细叶桉为母本,粗皮桉为父本的杂交成功率较高,授粉后至采种,成功率在93%以上,细叶桉与粗皮桉,EC18,U6的亲和性较大;与巨桉亲和性一般;与韦93亲和性相对较差。在母株相同的情况下,授粉过程中的人为影响是主要因素,包括操作过失对花蕾、树枝的无意伤害等;授粉后至采种主要受自然环境的影响,包括风、雨等因素。     

桉树无性系苗期光合作用特性研究

对6个桉树人工林高产无性系的苗期光合作用特性进行了测定,结果表明:尾叶桉净光合速率与光强呈显著的二次曲线相关关系,光响应的饱和点为1967 7μmol·m-2·s-1。桉树无性系具较高的净光合速率与蒸腾速率,不同无性系各项光合生理生态指标差异显著,尾×巨桉、尾×细桉等生长量较好的无性系较尾×赤桉和尾叶桉无性系的水分利用效率更高,光合能力更强。净光合速率、蒸腾速率及气孔导度三者日变化进程较为相似,而胞间CO2浓度的日变化趋势则与净光合速率相反。净光合速率、气孔导度与蒸腾作用与树高、胸径、单株材积等生长指标存在一定程度的正相关关系,可应用于优良无性系的早期选择。     

桉树杂交育种技术

桉树杂交育种是桉树遗传改良不可缺少的重要组成部分,能显著地提高按树人工林产量,也是开展抗性育种的有效途径。本文将桉树杂交育种过程中应注意的三个技术要点即明确杂交目的、杂交亲本的选择、确定杂交方式进行了概述。     

Morphology and molecular phylogeny of Erysiphe japonica var. japonica found on Quercus aliena in Korea

In October 2022, Erysiphe powdery mildew from the section Typhulochaeta was found on Quercus aliena for the first time in Korea. Based on morphological characteristics and molecular-phylogenetic analysis of the internal transcribed spacer region (ITS) and large subunit (LSU) gene sequences of the rDNA, the fungus was identified as Erysiphe japonica var. japonica. This is the first report of E. japonica var. japonica in Korea and the third report of this mildew on Q. aliena, with this current fungus-host association spreading to China and Japan. Based on Korean samples, this study provides detailed morphology and molecular phylogeny of E. japonica var. japonica.     

燃煤烟气脱硫副产物对桉树生长影响的研究

通过盆栽和大田试验,探讨脱硫副产物及以其为原料制作的土壤调理剂对提高桉树生长量的作用,结果表明:(1)适量施用脱硫副产物可有效提高桉树生长量,将其制作成土壤调理剂施用,可进一步提高产量。(2)供试物量过高或过低会导致肥效下降而引起桉树生长量下降。(3)适量施用供试物可有效防治因桉树微量元素供应不足导致的缺素垂梢病。     

闽西地区桉树引种栽培适应性调查分析

通过对闽西桉树引种栽培适应性调查分析,结果表明不同地理位置、海拔高度、立地质量及施肥次数对桉树生长存在显著差异,相同或相似条件下,不同的桉树品种(品系)生长量也不相同,所表现的耐寒性亦有差异。本文针对闽西地区目前桉树引种栽培存在的问题,提出了闽西今后发展桉树造林关键措施。     

Eucalyptus in agroforestry: its effects on agricultural production and economics

The economics of eucalyptus in agroforestry and its effects on agricultural crops have been studied with the help of observations made during the harvests in agricultural fields and from the information supplied by progressive farmers. Three rotations of eucalyptus in agroforestry were selected for comparative study of its returns and relative loss to the crops, in order to ascertain the optimum rotation: i.e. the one giving the maximum internal rate of return with minimum loss to agricultural crops.