[目的]明确火龙果茎溃疡病对火龙果植株茎组织真菌群落的影响,为揭示火龙果溃疡病发生机制及防治技术研究提供理论依据.[方法]采集火龙果健康植株和溃疡病发病植株茎组织,利用Illumina高通量测序平台对植株茎组织真菌rDNA的ITS序列进行测序,分析健康植株与发病植株茎组织中的真菌群落特征差异.[结果]火龙果健康植株茎组织的真菌群落多样性显著高于发病植株(P<0.05,下同),且健康植株与发病植株茎组织的真菌群落组成具有明显差异.与健康植株相比,发病植株茎组织的子囊菌门(Ascomycota)和担子菌门(Basidiomycota)相对丰度较高,分别为49.11%和10.90%,门分类水平的未知真菌(unclassified_k_Fungi)的相对丰度较低(39.97%).在属分类水平上,发病植株茎组织存在8个优势属,其中柱节孢属(Neoscytalidium)的相对丰度最高(33.29%),汉纳酵母属(Hannael-la)、Dirkmeia、丛赤壳科未知属(unclassified_f_Nectriaceae)和刺盘孢属(Colletotrichum)4个优势属的相对丰度显著高于健康植株,未在健康植株检测到柱节孢属、维希尼克氏酵母属(Vishniacozyma)和Meira;健康植株茎组织存在4个优势属,其中地霉属(Geotrichum)和链格孢属(Alternaria)的相对丰度显著高于发病植株.线性判别分析(LEfSe)结果显示,发病植株的柱节孢属和维希尼克氏酵母属以及健康植株的地霉属最能解释健康植株与发病植株间的差异.通过比对FUNGuild数据库预测真菌的营养型,发现发病植株中丰度最高的营养型为病理营养型(15.46%),健康植株中丰度最高的营养型是腐生营养型(7.95%).[结论]火龙果发生茎溃疡病后其茎组织的真菌群落多样性显著下降,真菌群落结构发生改变.当病原营养型真菌显著富集在茎组织中时会破坏茎组织的菌群平衡,可能促进了茎溃疡病的发生.

The pitaya canker disease is a serious fungal disease caused by Neoscytalidium dimidiatum. In recent years, the outbreak of the pitaya canker disease in the world’s pitaya producing areas has seriously affected the pitaya industry development. In order to study the expression level and function of genes responding to stress in N. dimidiatum, it is necessary to screen the reference genes that express stably when the pathogen grows under different cultural conditions. The N. dimidiatum strain LJ02 mycelia cultured in potato dextrose liquid medium（PDW）were taken as the control group, and the mycelia cultured in LB medium, and the mycelia cultured in PDW medium supplemented with hydrogen peroxide, pyrazolyl ester and difenoconazole, respectively, were taken as the treatment groups. The expression stabilities of 18candidate reference genes（CYT1, SDH2＿1, TBCC, SUI1, RPL19, PPH, ATP5B, UBE2＿16, RPL13, UBE2＿2, PRS17, SUCLA2, ATP5A,TUB1＿2, ACT1, EFTU, EF1A and GAPDH）were evaluated by real-time quantitative PCR（RT-qPCR）and stability evaluation software（geNorm, NormFinder, Bestkeeper and RefFinder）. Based on the results of RT-qPCR and software analysis, it was found that the Ct values of 18 candidate genes were within 14.80-24.66 under different culture conditions, with moderate expression levels. The reference gene with the highest stability was CYT1, followed by SUI1, while GAPDH and ACT1 were with the worst expression stability. Using at least two reference genes may improve analysis accuracy of RT-qPCR. At this time, SUCLA2 and ATP5A is the most stable reference gene combination. The results provide a theoretical basis for gene expression analysis in the biological process of N. dimidiatum.

通过田间药效试验的方法,评价9种常用杀菌剂对番茄灰霉病的防治效果,根据结果筛选出防治番茄灰霉病的有效药剂.结果 表明,按推荐剂量施药3次,400 g/L嘧霉胺悬浮剂,250 g/L嘧菌酯悬浮剂和50％腐霉利可湿性粉剂的防效分别为86.4％、82.3％和80.5％,高于其他供试药剂的防治效果.因此在生产上推荐轮换使用上述3种防效较高的杀菌剂,在灰霉病发生前期或初期开始喷药,每7～14d施药1次.

[目的]明确广西石漠化地区核桃主要病害种类,为其综合防控提供科学依据.[方法]调查广西河池市凤山县、东兰县、巴马县、天峨县、南丹县、环江县和金城江区等石漠化地区核桃病害的发生情况,并采集病害标本进行病原菌形态学特征观察;采用组织分离法分离病原菌,进行离体或活体接种确定其致病性,结合部分病原菌rDNA-ITS序列测定分析,鉴定主要病害的病原菌.[结果]广西石漠化地区核桃主要病害有胶孢炭疽菌(Colletotrichum gloeosporioides)引起的炭疽病,链格孢菌(Alternaria sp.)引起的黑斑病,胡桃楸拟茎点霉(Phomopsis juglandina)、多隔镰刀菌(Fusarium decemcellulare)和禾谷镰刀菌(F.graminearum)引起的枝枯病,葡萄座腔菌(Botryosphaeria dothidea)引起的溃疡病,腐皮镰刀菌(F.solani)和尖孢镰刀菌(F.oxysporum)引起的根腐病及胡桃球针壳(Phyllactinia juglandis)引起的白粉病.其中,多隔镰刀菌和禾谷镰刀菌引起核桃枝枯病为首次发现.核桃炭疽病可为害核桃的叶片、芽、嫩梢和果实;黑斑病可为害叶片、嫩梢和果实的青皮;枯枝病可为害小枝(尤其是1年生嫩枝);溃疡病可为害核桃树干及主侧枝基部;根腐病可为害根部;白粉病为害叶片.[结论]广西石漠化地区核桃主要病害有6种,其中发生最严重的是炭疽病,其次是黑斑病和枯枝病,生产上需重点防控.其他病害总体上发生较轻,但在局部地区发生严重时也需进行防控.

[目的]明确吡唑醚菌酯与苯醚甲环唑混配对核桃炭疽病菌(Colletotrichum gloeosporioides)的联合毒力和林间防治效果,为核桃炭疽病综合防控提供科学依据.[方法]采用菌丝生长速率法测定吡唑醚菌酯和苯醚甲环唑单剂及其不同配比混剂对核桃炭疽病菌菌丝生长的毒力;利用喷雾法进行林间防治试验,评价吡唑醚菌酯与苯醚甲环唑混剂对核桃炭疽病的林间防治效果.[结果]室内联合毒力测定结果表明,吡唑醚菌酯与苯醚甲环唑按质量比3:2和1:1进行复配对核桃炭疽病菌菌丝生长的毒力表现为增效作用,增效系数分别为1.61和1.57;其他配比的增效系数在0.91～1.41,表现为相加作用.林间对核桃炭疽病的防治试验结果表明,250 g/L吡唑醚菌酯乳油与250 g/L苯醚甲环唑乳油以质量比3:2进行混配(吡唑醚菌酯和苯醚甲环唑的含量分别为150和100 g/L),施用剂量为有效成分125.0、166.7和250.0 mg/L时对核桃炭疽病有很好的防治效果,施药3次后防治效果均在80.0％以上,分别与325 g/L苯甲·嘧菌酯悬浮剂(苯醚甲环唑125 g/L+嘧菌酯200 g/L)施用剂量为有效成分162.5、216.7和325.0 mg/L时的防治效果相当;250 g/L苯醚甲环唑乳油125.0 mg/L的林间防治效果也较好,而250 g/L嘧菌酯悬浮剂166.7 mg/L和250 g/L吡唑醚菌酯乳油166.7 mg/L的防治效果稍低.[结论]吡唑醚菌酯与苯醚甲环唑以质量比3:2混配具有较好的增效作用,林间对核桃炭疽病具有良好的防治效果,可作为防治核桃炭疽病的药剂推广应用.

Pitaya fruits collected from Nanning,Qinzhou and Fangchenggang counties were stored at 28 ℃ to investigate the occurrence of postharvest diseases..Pathogens were isolated from the diseased tissue and identified based on morphological characteristics and rDNA-ITS sequence analysis.Results showed that soft rot (Fusarium equiseti (Corda) Sacc.,Gilbertella persicaria (Eddy)Hesselt.),black spot (Alternaria alternata (Fr.) Keissl.,Bipolaris cactivora (Petrak)Alcorn)and canker (Neoscytalidium dimidiatum (Penz.) Crous & Slippers) were detected from the postharvest fruits.Fusarium equiseti causing soft rot disease in dragon fruit was reported at the first time.

[目的]明确吡唑醚菌酯等杀菌剂对火龙果溃疡病的室内抑菌活性和田间防效,为火龙果溃疡病综合防控提供科学依据.[方法]采用菌丝生长速率法测定吡唑醚菌酯等5种杀菌剂对火龙果溃疡病菌菌丝生长的室内抑菌活性;利用田间植株喷雾法评价250 g/L吡唑醚菌酯乳油125.0、166.7和250.0 mg/kg,250 g/L嘧菌酯悬浮剂250.0 mg/kg,430 g/L戊唑醇悬浮剂215.0 mg/kg,10％己唑醇悬浮剂60.0 mg/kg和400 g/L氟硅唑乳油133.3 mg/kg对火龙果溃疡病的田间防治效果.[结果]室内毒力测定结果表明,己唑醇、戊唑醇、氟硅唑和吡唑醚菌酯对火龙果溃疡病菌菌丝生长均有较好的抑制作用,抑制中浓度(EC50)分别为0.0749、0.2325、0.5277和1.8572μg/mL,而嘧菌酯的抑制作用稍弱,EC50为18.5655μg/mL.田间小区防治试验结果证明,250 g/L吡唑醚菌酯乳油对火龙果溃疡病有很好的防效,施药3次后,250 g/L吡唑醚菌酯乳油125.0、166.7和250.0 mg/kg对茎溃疡病的防效分别在60.0％、70.0％和80.0％以上,对果实溃疡病的防效分别在65.0％、75.0％和85.0％以上.250 g/L嘧菌酯悬浮剂250.0 mg/kg和430 g/L戊唑醇悬浮剂215.0 mg/kg对火龙果溃疡病也有较好的防效,分别与250 g/L吡唑醚菌酯乳油166.7和125.0 mg/kg的防效相当.10％己唑醇悬浮剂60.0 mg/kg和400 g/L氟硅唑乳油133.3 mg/kg的田间防效较差.[结论]吡唑醚菌酯、嘧菌酯和戊唑醇对火龙果溃疡病均具有良好的防效,可作为防治火龙果溃疡病的药剂在生产上推广应用.