Curent Situation of “Candidatus Liberibacter asiaticus” in Guangdong,China,Where Citrus Huanglongbing Was First Described

Citrus Huanglongbing （HLB,yellow shoot disease） was first observed in the coastal Chaoshan Plain of Guangdong Province,China,in the late 19th century based on descriptions of yellow shoot symptoms. “Candidatus Liberibacter asiaticus”has been considered as a putative pathogen associated with HLB since 1994.Information about the curent prevalence of this bacterium is important for HLB control in Guangdong and also provides useful reference for HLB study elsewhere.In 2007,we collected HLB symptomatic citrus samples from 16 cultivars in 12 prefecture cities,mostly in the north and west regions of Guangdong,where major citrus fruits are currently produced.Among the 359 samples collected,241 （67.1%） were positive for “Ca.L.asiaticus”,distributed in 15 out of the 16 cultivars from all 12 cities,indicating the widespread prevalence of “Ca.L.asiaticus” in Guangdong Province.The detection rates varied from 16.7 to 100% depending on location and cultivar.Lower detection rates were found in newer citrus cultivation cities among the previously less popular but now promoted cultivars.In reviewing the citrus management and pest control practice,we believe that infected nursery stocks play a key role in the current spread of “Ca.L.asiaticus”.

Digital Gene Expression Analysis of Huanglongbing Affected Mandarins(Citrus reticulata Blanco)In Response to Thermotherapy

Huanglongbing(HLB),which is mainly associated with“Candidatus Liberibacter asiaticus”(CLas),is currently threatening citrus production around the world.This destructive century-old disease results in callose deposition in phloem plasmodesmata and starch overaccumulation in leaf chloroplasts.Heat treatment with high humidity has proven to be effective in eliminating the CLas titers in potted citrus trees.This study explored the curative mechanisms and impact of heat treatment(from 32 to 48°C with 75%±5%relative humidity,14h in light and 10h in dark for four days)on mandarin trees(Citrus reticulata Blanco)that were severely infected by CLas using Solexa/Illumina’s digital gene expression(DGE)profiling.A total of 838 differentially expressed genes(DEGs)were identified,of which 510 were downregulated.Proteinprotein interaction analysis of the DEGs indicated that the thermotherapy of HLB trees downregulated the circadian clock related genes in chloroplasts and upregulated the RNA-editing process in the mitochondria,characterized by 141 genes encoding pentatricopeptide repeatcontaining proteins(PPR)being all upregulated.Furthermore,the expression of phenylpropanoid and flavonoid biosynthesis genes,and auxininduced genes were suppressed.The defense response pathway of the thermotherapy treated diseased trees was apparently disrupted,as indicated by the downregulation of LRR receptor-like serine/threonine-protein kinase FLS2 gene.This study improves our understanding of the curative mechanisms of heat treatment on HLB trees and CLas biological regulation.Importantly,this provides new insights on the involvement of RNA modification by PPR genes and changes in the circadian clock after the heat stress treatment of CLas-infected citrus.

Prevention and Control Measures of Citrus Huanglongbing and Application Ideas of Repellent Plants

Citrus huanglongbing is the most infectious and destructive disease in citrus production in the world.The essential characteristics,transmission routes and severity,and diagnosis of citrus huanglongbing,as well as control methods and effects of Diaphorina citri are summarized,and the application ideas of repellent plants is put forward.

Field Identification and Prevention and Control Techniques of Citrus Huanglongbing of Orah Mandarin

In order to promote the development of Orah mandarin industry in Guangxi and reduce the harm of citrus huanglongbing to Orah mandarin,the pathogen,characteristics,occurrence regularity and field symptoms of citrus huanglongbing were summarized,and scientific prevention and control measures were put forward,such as strict implementation of quarantine system,cultivation and use of disease-free seedlings,strengthening field management,timely control of psyllid,timely removal of diseased trees,etc.

A Rapid Identification Method for Germplasm Materials Resistant to Citrus Huanglongbing Disease

[Objectives]This study was conducted to develop a rapid identification method for citrus germline materials resistant to Huanglongbing disease and lay a basis for accelerating citrus breeding for resistance to Huanglongbing and increasing the breeding efficiency.[Methods]Thirty-six citrus germplasms suspected to be resistant to citrus Huanglongbing disease were collected.The method of direct high grafting to citrus trees infected with Huanglongbing pathogen was adopted.The resistance of the test materials was identified and evaluated by field symptoms combined with quantitative PCR.It was defined as the top grafting identification method.[Results]The test materials that were grafted in spring started to germinate after one month,and three months late(June 5,2018)typical mottled yellowing on leaves was observed on KH-14 for the first time.After four months(July 5,2018)of top grafting,typical mottled yellowing occurred on 23 materials,and 11 materials showed no such symptom.After six months(September 4,2018)of top grafting,although the growth of KH-18,KH-12,KHY-4,KHY-5 and KHY-6 were normal,yellowing was observed on their leaves.Only KH-21 grew well,and showed no yellow shoots and yellowing leaves.It was identified as the material with resistance to Huanglongbing disease.Quantitative PCR tests on the above six materials showed that KH-21 was negative and other five were positive.Real-time fluorescence quantitative PCR test indicated that the average Huanglongbing bacteria amount in KH-21 was 1870.0 cell/μg DNA,and the average Huanglongbing bacteria amount in the control material was 372285.5 cell/μg DNA,indicating KH-21 was resistant to Huanglongbing bacteria.[Conclusions]The method for infecting bacteria by top grafting takes six months,can detect large amount of seedlings,and is time-saving,efficient,cost-saving and accurate.This method can quickly identify the resistance of citrus varieties to citrus Huanglongbing disease,and can be popularized and used in the identification of citrus Huanglongbing disease resistance.

Epidemic Regularity and Control Effect of Huanglongbing (HLB) in Different Management Approaches

In order to reveal the epidemic regularity of Huanglongbing （HLB） in different management approaches, different citrus production areas were selected between 2002 and 2012 to compare epidemic regularity of different types and control effects of different management approaches with plant incidence rate. All survey data in 11 years were used to build a mathematical model, and epidemic evolution and control effects were quantitatively analyzed. The results indicated that diffusion and prevalence of HLB generally increased linearly. In naturally growing citrus orchards without artificial control, the annual diseased plant rate was 11.11%, and the epidemic diffusion model was y1 = 12. 24x - 1.382 8 （ n =9, r =0. 976 9 ＊ ＊ ）. Under general prevention and control conditions, the annual diseased plant rate was 4.69%, the epidemic diffusion model was Y2 = 5. 449 8x - 1.603 5 （ n = 11, r =0. 974 9 ＊ ＊ ）, and the control effect was 43.93% （22.93% - 55.04% ）. In citrus orchards with integrated prevention and control, the epidemic diffusion model was Y3 = 0. 366 3x - 0. 342 2 （ n = 11, r = 0. 989 8 ＊ ＊ ）, the control effect was 96.15% （94.95% -97.40% ）, and the annual diseased plant rate was 0.31%. Thus, HLB is preventable and controllable as long as integrated prevention and control work is implemented well.

Identification and Control of HLB Disease in Citrus grandis

HLB disease has been endangering citrus production,and it is an important task in Citrus grandis production to identify and control HLB disease. Diaphorina citri and Trioza erytreae are the main vectors for the spreading of HLB disease. Scientific and proper release of predatory natural enemies such as ladybugs,combined with chemical control can effectively control psyllid. For suspected HLB disease strains,a simple " HLB disease detection reagent" can be used for detection. This method is simple,cheap and accurate,and it is an economical and feasible identification method for ordinary growers.

Transcriptomic analysis reveals the defense mechanisms of citrus infested with Diaphorina citri

Huanglongbing(HLB) is a devastating disease that has led to an acute crisis for growers of citrus, one of the world's most important fruit crops. The phloem-feeding Asian citrus psyllid(ACP), Diaphorina citri, is the main pest at the new shoot stage and is the only natural vector of HLB pathogenic bacteria. Little is known about how plants perceive and defend themselves from this destructive pest. Here, we characterized changes in the expression of various genes in citrus plants that were continuously infested by D. citri for different durations(12, 24, and 48 h). A total of 5 219 differentially expressed genes(DEGs) and 643 common DEGs were identified across all time points. Several pathways related to defense were activated, such as peroxisome, alpha-linolenic acid metabolism, and phenylpropanoid and terpenoid biosynthesis, and some pathways related to growth and signal transduction were suppressed in response to D. citri infestation. The expression of genes including kinases(CML44, CIPK6, and XTH6), phytohormones(SAMT, LOX6, and NPR3), transcription factors(bHLH162, WRKY70, and WRKY40), and secondary metabolite synthesis-related genes(PAL, 4CL2, UGT74B1 and CYP82G1) was significantly altered in response to D. citri infestation. The findings of this study greatly enhance our understanding of the mechanisms underlying the defense response of citrus plants to D. citri infestation at the molecular level. Functional characterization of the candidate defense-related genes identified in this study will aid the molecular breeding of insect-resistant citrus varieties.

柑橘黄龙病菌在三红蜜柚发病早期对果实品质影响的定量分析

柑橘黄龙病是危害橘、橙、柚、柠檬等柑橘类水果的主要病害。与橘、橙相比,柚感染黄龙病后发病慢、症状轻。生产中蜜柚轻病树带病产果现象普遍。为明确黄龙病感染早期对蜜柚果实品质的影响,本研究在黄龙病轻病园中,对三红蜜柚果实品质与柑橘黄龙病菌含量做了定量分析。研究发现,蜜柚感染黄龙病早期,柑橘黄龙病菌含量在0至2^(14)范围内,果实外在品质的主要指标全果重、果形指数、果皮率都没有显著差异;果实内在品质可食率、可溶性固形物和固酸比下降,可滴定酸升高,变化差异都达到显著(P<0.05)或极显著的水平(P<0.01)。实验结果表明,柑橘黄龙病感染早期对三红蜜柚果重、果皮率等外在品质影响轻微,对三红蜜柚果实可溶性固形物等内在品质影响严重。生产上应重视柑橘黄龙病对蜜柚果实品质下降的影响。

The Citrus Huanglongbing Crisis and Potential Solutions

Citrus is one of the top three fruit crops worldwide.Citrus production is facing an unprecedented crisis due to Huanglongbing(HLB,also known as citrus greening),which is the most devastating disease of citrus.HLB was first reported in Asia a century ago.HLB is associated with Candidatus Liberibacter asiaticus(Las),Ca.L.americanus(Lam),and Ca.L.africanus(Bove,2006),which belong to the gramegative a-proteobacteria.Among them,Las is the most widely spread.Las and Lam are vectored by Diaphorina citri Kuwayama(ACP),whereas Laf is transmitted by Trioza erytreae.

Huanglongbing:An overview of a complex pathosystem ravaging the world's citrus

Citrus huanglongbing（HLB） has become a major disease and limiting factor of production in citrus areas that have become infected. The destruction to the affected citrus industries has resulted in a tremendous increase to support research that in return has resulted in significant information on both applied and basic knowledge concerning this important disease to the global citrus industry. Recent research indicates the relationship between citrus and the causal agent of HLB is shaped by multiple elements, in which host defense responses may also play an important role. This review is intended to provide an overview of the importance of HLB to a wider audience of plant biologists. Recent advances on host-pathogen interactions, population genetics and vectoring of the causal agent are discussed.

Detection of Huanglongbing(citrus greening) based on hyperspectral image analysis and PCR

Huanglongbing (HLB, citrus greening) is one of the most serious quarantine diseases of citrus worldwide. To monitor in real-time, recognize diseased trees, and efficiently prevent and control HLB disease in citrus, it is necessary to develop a rapid diagnostic method to detect HLB infected plants without symptoms. This study used Newhall navel orange plants as the research subject, and collected normal color leaf samples and chlorotic leaf samples from a healthy orchard and an HLB-infected orchard, respectively. First, hyperspectral data of the upper and lower leaf surfaces were obtained, and then the polymerase chain reaction (PCR) was used to detect the HLB bacterium in each leaf. The PCR test results showed that all samples from the healthy orchard were negative, and a portion of the samples from the infected orchard were positive. According to these results, the leaf samples from the orchards were divided into disease-free leaves and HLB-positive leaves, and the least squares support vector machine recognition model was established based on the leaf hyperspectral reflectance. The effect on the model of the spectra obtained from the upper and lower leaf surfaces was investigated and different pretreatment methods were compared and analyzed. It was observed that the HLB recognition rate values of the calibration and validation sets based on upper leaf surface spectra under 9-point smoothing pretreatment were 100% and 92.5%, respectively. The recognition rate values based on lower leaf surface spectra under the second-order derivative pretreatment were also 100% and 92.5%, respectively. Both upper and lower leaf surface spectra were available for recognition of HLB-infected leaves, and the HLB PCR-positive leaves could be distinguished from the healthy by the hyperspectral modeling analysis. The results of this study show that early and nondestructive detection of HLBinfected leaves without symptoms is possible, which provides a basis for the hyperspectral diagnosis of citrus with HLB.

Detection of citrus Huanglongbing based on image feature extraction and two-stage BPNN modeling

Citrus Huanglongbing(HLB),which is spread by the citrus psyllid,is the most destructive disease of citrus industry.While no effective cure for the disease has been reported,detection and removal of infected trees can prevent spreading.Symptoms indicative of HLB can be present in both HLB-positive trees and HLB-negative trees,making identification of infected trees difficult.A detection method for citrus HLB based on image feature extraction and two-stage back propagation neural network(BPNN)modeling was investigated in this research.The identification method for eight different classes including healthy,HLB and non-HLB symptoms was studied.Thirty-four statistical features including color and texture were extracted for each leaf sample,following the two-stage BPNN to model and identify HLB-positive leaves from HLB-negative leaves.The discrimination accuracy can reach approximately 92%which shows that this method based on visual image processing can perform well in detecting citrus HLB.

黄龙病发病芦柑根际土壤细菌群落组成与多样性特征

【目的】本研究旨在研究福建南平地区芦柑(Citrus reticulata)植株根际土壤细菌群落,并分析黄龙病对其细菌群落的影响,为南平地区芦柑黄龙病的防控提供科学依据。【方法】采用五点法采集了健康和黄龙病发病的芦柑植株根际土壤样本,通过扩增子测序技术和生物信息学方法,深入研究了黄龙病发病芦柑根际土壤细菌群落的多样性和组成变化,分析了土壤理化因子与细菌群落的关联性。【结果】研究结果表明,黄龙病发病的芦柑植株根际土壤细菌群落的多样性略高于健康植株。黄龙病发病芦柑根际土壤中的变形菌门相对丰度明显升高,而放线菌门相对丰度显著降低。在属水平上,与健康植株相比,黄龙病发病芦柑植株根际土壤细菌群落中蔷薇属和嗜酸性杆菌属的相对丰度显著增加,与速效钾、有效磷以及有机质呈现显著负相关,而与pH值呈现显著正相关。相反地,康奈斯氏杆菌属和褚氏杆菌属的相对丰度明显低于健康植株,并与速效钾、有效磷以及有机质呈现显著正相关,同时与p H值呈现显著负相关。【结论】黄龙病菌感染改变了柑橘土壤理化特性,并显著减少根际土壤中有益细菌的相对丰度,从而导致了芦柑植株根际细菌群落的多样性和组成出现显著变化。与此同时,黄龙病发病的芦柑植株可能通过招募固氮和促进植物根际生长的有益细菌来对抗病原菌的侵害。

柑橘黄龙病菌效应子致病机制研究进展

柑橘黄龙病(Citrus Huanglongbing,HLB)是全世界范围内为害最严重的柑橘病害之一,每年对柑橘生产造成巨大损失,严重影响全球柑橘产业发展。在中国岭南地区,重要药用植物茶枝柑、化州柚、广佛手等均受到柑橘黄龙病的威胁。亚洲韧皮部杆菌(Candidatus Liberibacter asiaticus,CLas)是最常见的柑橘黄龙病致病菌株,该菌定殖于植物的韧皮部,主要感染芸香科柑橘属(CitrusL.)植物。目前尚无体外成功培养亚洲韧皮部杆菌的报道,因此对柑橘黄龙病致病机制研究和黄龙病防治均有较高难度。效应子(又称效应蛋白)是病原菌向宿主分泌的一类致病因子,是病原菌侵染植物的重要武器。效应子能够靶向宿主细胞关键免疫信号转导和调控组分,从而抑制植物防御反应,增强病原菌致病性。柑橘黄龙病菌能够分泌近百个效应子,根据分泌途径的不同,主要分为Sec依赖型效应子和非经典分泌效应子,其中Sec依赖型效应子有90个、非经典分泌效应子有15个。这些效应子在柑橘黄龙病菌侵染宿主过程中发挥关键作用。已有研究发现,黄龙病菌效应子能够靶向包括植物免疫信号转导、细胞自噬、水杨酸信号途径等多个生物学过程,从而干扰宿主柑橘的防御反应,以促进黄龙病菌的定殖。该文结合近年来有关柑橘黄龙病菌效应子致病机制的研究,阐述了柑橘黄龙病研究概况、黄龙病菌效应子的分类,重点综述了影响柑橘防御反应的柑橘黄龙病菌效应子的致病机制,最后展望了黄龙病菌效应子的未来研究趋势和方向,讨论了基于效应子靶标寻找黄龙病重要抗性基因的可能性,期望通过亚洲韧皮部杆菌效应子研究,为柑橘黄龙病致病机制研究和病害防控提供指导。

柑橘黄龙病菌亚洲种分子检测引物评价及绝对定量PCR体系优化

柑橘黄龙病是对柑橘产业最具毁灭性的病害,目前没有可用的有效药剂和抗病品种,分子检测对黄龙病有效防控至关重要。本研究对国内外常用的常规PCR和巢式PCR检测引物进行评价,针对多拷贝的nrdB和16S rDNA基因,构建质粒标准品并筛选适用于绝对定量PCR的最佳质粒。结果表明,使用Es Taq MasterMix对感染Candidatus Liberibacter asiaticus(C Las)的柑橘样品进行常规PCR检测时,在评价的16对引物中,OI1/OI2c、Las606/LSS和HLBF468/R877灵敏度最高,推荐同时使用检测黄龙病菌含量低的样品;各组巢式PCR检测引物有其适用扩增体系,部分引物用Es Taq MasterMix扩增时出现非特异性扩增,F1/B1→F3/B3则适用Es Taq MasterMix体系,且最高可稳定特异检出10^(5)倍稀释感染C Las柑橘总DNA样品(2×10^(-3) ng/μL),是灵敏度最高的引物组,OI1/OI2c→S3/S4在Es Taq MasterMix和Ex Taq DNA聚合酶体系中均可稳定特异检出104倍稀释感染C Las柑橘总DNA样品(2×10^(-2) ng/μL),是适用扩增体系最广的引物组;构建的5个绝对定量PCR质粒标准品中,pnrdB83扩增效率最接近100%,且在2次重复试验中波动最小,稳定性最强,并且作为标准品对黄龙病待测样品进行绝对定量时,各样品在2次重复试验中的拷贝数差值最小,是本研究筛选的最佳质粒。本研究的结果将为柑橘黄龙病菌的定性和定量分子检测提供参考。

基于可见光谱特征波长提取和分类算法的柑橘黄龙病快检研究

柑橘黄龙病(HLB)是由亚洲韧皮杆菌引起的一种严重病害,目前无法根治。其防控具有重要意义和经济价值。当前利用健康和患病叶片的光谱差异对其进行诊断显示了良好的应用前景。因患病叶片在叶绿素反射区及O—H伸缩振动区的可见光谱与健康叶片存在显著差异,而可见光谱检测在采集和数据处理方面具有成本低、简便的优势,研究可见光谱的黄龙病快速检测方法具有可行性和重要意义。为了减少光谱数据冗余和计算量,实现精准的黄龙病的早期鉴别以及降低黄龙病相似病症的误诊率,采集了黄龙病患病地区共160个叶片样本。经qPCR测定分别将其分类标定为健康、轻度疾病、重度疾病和缺镁症四类。根据叶片样本在可见光波段450~800 nm的反射光谱特征,通过S-G平滑以及降采样等预处理光谱数据后,为了优选出尽可能囊括光谱特征信息的特征波长,分别使用遗传算法(GA)、连续投影算法(SPA)以及竞争自适应重加权采样法(CARS)对采集到的可见光谱数据进行特征波长提取和降维优选出特征波长,进一步降低模型复杂度,提高预测精度。综合泛化能力及检测速度的考量,在定性判别分析模型的选择中采用训练速度快,分析准确率高的最小二乘支持向量机(LS-SVM)以及随机森林(RF)对两种变量筛选算法降维后的数据进行分类判别。通过对不同的模型的验证优选,筛选出最佳的快检方案。对比发现,在建立的模型中,SPA-RF模型与其他模型比较,对于训练集和测试集的判别准确率分别达到了100%和97.5%。结果表明,连续投影算法以及随机森林的组合分类模型可以很好地实现黄龙病早期的病理鉴别,同时也能够很好地识别出黄龙病病叶与其他相似病症的差异,为柑橘黄龙病快速检测及防治提供了一种方法依据。

柑橘黄龙病菌亚洲种重复序列分析及其检测引物筛选

由柑橘黄龙病菌亚洲种(Candidatus Liberibacter asiaticus,CLas)引起的黄龙病(Huanglongbing,HLB)对柑橘产业危害严重,通过加强病原检测有利于减少病害传播。利用高拷贝重复序列位点设计引物,虽能提高黄龙病检测的灵敏度,但重复序列的多态性很难保障引物检测特征稳定。通过比较11个CLas全基因组的重复序列,以期获得保守的重复序列,利于开发通用型CLas检测引物。结果显示,CLas全基因组有4段长度>50 bp的高拷贝重复序列,其重复数量和序列在11个菌株中均具有保守性。基于4段重复序列开发了CLas特异的6对引物,均能稳定检测田间柑橘黄龙病样品,熔解曲线吸收峰单一,熔解温度稳定。比较6对引物的灵敏度,发现基于5个拷贝重复序列开发的IR16-fr灵敏度最高。使用IR16-fr和常规引物CQULas-FR对50份田间柑橘叶片样品进行检测,结果显示,CQULas-FR对CLas的检出率为20%,而IR16-fr的检出率为26%。新引物IR16-fr可为田间CLas高效率检测提供技术支撑。

发根农杆菌介导的柑橘黄龙病抗性快速评价体系优化及应用

【目的】黄龙病(Huanglongbing,HLB)是一种毁灭性柑橘病害,主要由韧皮部杆菌属亚洲种(Candidatus Liberibacter asiaticus,CLas)侵染引起。本研究旨在探究侵染初期CLas在柑橘毛状根中的增长规律,优化发根农杆菌(Agrobacterium rhizogenes)介导的黄龙病抗性快速评价体系并应用于抗菌肽的抗性评价。【方法】基于植物表达载体pGNGM1300,通过发根农杆菌K599介导的毛状根转化体系转化不同柑橘品种,筛选毛状根诱导快、转化率高的品种;接种CLas后,利用实时荧光定量PCR(real-time quantitative PCR,qPCR)对毛状根中的CLas进行定期检测,揭示其增长规律;在优化黄龙病抗性评价体系的基础上,通过CLas和相关基因的(RT-)qPCR、胼胝质含量检测、显微结构观察和症状观察等开展抗菌肽的黄龙病抗性评价。【结果】供试的11个柑橘品种中,香橼(Citrus medica)的毛状根诱导最快(15 d)、诱导率最高(73.75%),并且毛状根中转基因阳性率高(53.54%)。qPCR定期监测结果显示,在接种后第20—30天(days post inoculation,dpi),CLas开始在根中定殖;在30—50 dpi,CLas含量呈显著上升的趋势;CLas含量在60—120 dpi时略有波动,但与50 dpi时差异不显著。抗菌肽MaSAMP(stable antimicrobial peptide)、HBD-4(homo sapiens defensin beta 4)和CB(cecropin B)的抗性评价结果分析显示,在50—120 dpi,MaSAMP和CB表达植株中CLas含量均低于对照,且差异显著,除90 dpi外HBD-4表达植株中CLas含量也显著低于对照。3种抗菌肽表达植株中的胼胝质含量均显著低于对照(60 dpi),韧皮部细胞壁增厚不明显,未出现明显的淀粉粒和胼胝体沉积,并且均未发现根部死亡等现象(90 dpi)。【结论】揭示了侵染早期CLas在柑橘毛状根中的增长规律;优化了发根农杆菌介导的黄龙病抗性快速评价体系;明确转基因过表达抗菌肽MaSAMP、HBD-4和CB可显著抑制CLas的增殖,减少胼胝质沉积,减轻黄龙病症状,具有用于黄龙病防控实践的潜力。

网室栽培对广东惠州地区柑桔生长及病虫害发生的影响

柑桔黄龙病是柑桔生产上的毁灭性病害,在田间主要通过柑桔木虱(Diaphorina citri Kuwayama)传播,目前尚无有效防治柑桔黄龙病的药剂。防虫网室种植柑桔是目前国内多个黄龙病高发区用以防控柑桔木虱及黄龙病的新型种植方式。2020年1月至2021年2月在广东惠州(黄龙病流行区)的一个沙糖桔结果园中,设置防虫网覆盖区和露天区,对网室区与露天区的树势、黄龙病流行状况、柑桔木虱发生情况、其他害虫发生情况及温湿度进行跟踪调查,并分析其差异。结果显示,与露天比较,防虫网室种植有利于增强健康植株的树势,对产量无不利影响;网室对温湿度的影响主要表现在湿度上,5月和7月网室内相对湿度分别升高1.96和1.81百分点,10月和11月网室内相对湿度分别降低6.73和7.20百分点;网室种植能减少柑桔害虫发生种类,减少柑桔木虱发生数量,减轻黄龙病病情,但会引起全年性粉虱数量增加和秋季(10-11月)柑桔全爪螨暴发。