采用38%吡虫啉。噻嗪酮悬浮剂防治芒果介壳虫。田间试验结果表明，38%吡虫啉·噻嗪酮悬浮剂对芒果介壳虫具有较好的防治效果，按照253mg/kg的使用量，第一、二次田间使用该药剂，防效分别为82.94%、89.96%，明显高于对照药剂35%吡虫啉悬浮剂(使用量253mg/kg)的防效(76.84%、82.18%)和40%噻嗪酮悬浮剂(253mg/kg)的防效(76.85%、83.96%)。试验期间未发现该药剂在供试剂量下对芒果产生药害。

Previous studies indicate that the plant genus Allium,including bulb onion(A.cepa L.),can be infected by at least seven species of Botrytis at the stages of growth and/or storage(Nielsen et al.,2002).Of these Botrytis species,three,namely B.aclada,B.allii,and B.byssoidea,were reported to be most commonly associated with neck rot of onion(Nielsen et al.,2002).B.aclada was regarded as synonymous with B.allii until 2003,when Yohalem et al.(2003)suggested that both B.aclada and B.allii are valid names.Further analysis showed that B.allii is a hybrid of B.aclada and B.byssoidea(Nielsen and Yohalem,2001)and the hybrid status of B.allii was confirmed in a molecular phylogenetic study conducted by Staats et al.(2005).In China,B.allii was reported to cause brown rot of onion bulbs(Tan et al.,1997),whereas rot of onion bulbs caused by B.aclada has not been documented in this country.In spring of 2006,a kind of rot disease was observed among sold onion bulbs in the supermarket near the campus of Huazhong Agricultural University,Wuhan,China.Surveys of five randomly-selected stacks of onion bulbs in that market indicated that the percentage of diseased bulbs varied from 6 to 50%.Diseased onion bulbs became soft rotten and abundant conidia were produced on the surface of diseased bulb tissues of onion showing a grey powdery appearance.Eight fungal isolates were obtained from 8 diseased bulbs of onion showing the grey mould symptoms.They were individually incubated on potato dextrose agar(PDA)at 20℃ and identified on the basis of cultural and morphological characteristics.Results showed that all of these isolates produced abundant grey-brownish,ovoid-or oblong-shaped conidia,which were budded from terminal ampullae formed on dichotomously-branching conidiophores.The size of conidia for these isolates varied from 7.6 to 10.4 μm in length and from 4.2 to 5.6 μm in width.No sclerotia were produced by these isolates on PDA even after incubation for 30 days.These characteristics of the investigated fungal isolates are similar to those described for B.aclada by Yohalem et al.(2003).One of the eight fungal isolates,OnionBc-15,was used for further identification using molecular methods.Genomic DNA(gDNA)was extracted from mycelia of OnionBc-15 and used as template for amplification of certain DNA regions.The first targeted DNA region is the internal transcribed spacer(ITS)of the ribosomal RNA gene.It was amplified with the universal primer pair ITS1 and ITS4(Nielsen et al.,2002).A 539-bp DNA fragment was generated,cloned and sequenced(GenBank Acc.No.EU093077).The sequence contained two SphI restriction sites and was 99%identical in nucleotides to that of B.aclada strain PRI006(GenBank Acc.No.AJ716295).It is different from B.allii and B.byssoidea,which have only one SphI restriction site for the ITS1/ITS4-amplified DNA sequence(Nielsen et al.,2002).The second targeted DNA region is the L45-550 sequence(Nielsen&Yohalem,2001).It was amplified with the Botrytis-specific primer pair BA2f and BA1r(Nielsen et al.,2002).A 413-bp DNA fragment was generated,cloned and sequenced.Sequencing analysis showed that the 413-bp DNA fragment did not contain any ApoI restriction sites.This is also similar to B.aclada,but different from B.allii and B.byssoidea,which have one ApoI restriction site in the BA2f/BA1r-amplified DNA sequence(Nielsen et al.,2002).Additionally,three house-keeping genes encoding glyceraldehyde-3-phosphate dehydrogenase(G3PDH),heat-shock protein 60(HSP60)and DNA-dependent RNA polymerase subunit II(RPB2)were amplified from the gDNA of OnionBC-15 with the specific primer pairs reported by Staats et al.(2005).The generated DNA fragments were 886 bp for G3PDH,977 bp for HSP60 and 1093 bp for RPB2,which were cloned and sequenced.They were assigned with GenBank accession numbers as EU100386,EU100387 and EU093078,respectively.Phylogenetic trees were established on the basis of the sequence information of G3PDH,HSP60 or RPB2 cloned from OnionBC-15 in this study and from the 22 species of Botrytis reported by Staats et al.(2005)using the neighbor-joining(NJ)method implemented in the MEGA3.1 package.Each phylogenetic tree was tested with bootstrap(1000 replicates).Results showed that OnionBc-15 was more closely related to B.aclada and B.allii than to other species of Botrytis in each phylogenetic tree.Therefore,it is appropriate to identify the strain OnionBC-15 as B.aclada.This research was funded by the Natural Science Foundation of China(Grant No.30570079).[1]Nielsen K,Yohalem DS.Origin of a polyploid Botrytis pathogen through interspecific hybridization between Botrytis aclada and B.byssoidea.Mycologia,2001,93:264~271.[2]Nielsen K,Yohalem DS,Jensen DF.PCR detection and RFLP differentiation of Botrytis species associated with neck rot of onion.Plant Disease,2002,86:682~686.[3]Staats M,van Baarlen P,van Kan JAL.Molecular phylogeny of the plant pathogenic genus Botrytis and the evolution of host specificity.Molecular Biology and Evolution,2005,22:333~346.[4]Tan WZ,Wang XY,Zhang LX.Two newly recorded fungal diseases of Allium in Yunnan province,China.J.Southwest Agri.Univ.,1997,19:165~167.[5]Yohalem DS,Nielsen K,Nicolaisen M.Taxonomic and nomenclatural clarification of the onion neck rotting Botrytis species.Mycotaxon,2003,85:175~182.

豆瓣菜（Nasturtium officinale R.Br.）又名西洋菜、水蔊菜、水田芥，属十字花科豆瓣菜属植物。枝叶柔嫩青翠，性喜冷凉，较耐霜冻，是深受人们喜爱的冬春上市的水生绿叶蔬菜。有关豆瓣菜菌核病国内尚未有专门报道。该病1999年在武汉旱地栽种的豆瓣菜田中仅见零星发生，到2001年春发病田中的发病面积可达1.61%，甚至到10%左右，表明病害有增重的趋势。豆瓣菜的茎、叶、叶柄均可受害。以中、下部贴近地面匍匐或半匍匐生长的枝叶受害最重。田间病害呈点片状发生，不规则分布。因豆瓣菜分枝多，生长繁茂，茎呈匍匐或半匍匐丛生，故发病初期常需拨开丛生状植株，才能发现感病枝叶，后期因植株枯死而呈现近圆形至不规则形病区。茎部受害，水渍状，淡褐色，边缘不清晰，从病处向两端扩展，空气湿度大时生茂密的绵毛状白霉，继而在植株表面及病茎的空腔中菌丝集结成近球形、扁球形、鼠粪状或不规则的菌核。菌核初白色，成熟后黑色，内部白色。罹病植株病部软腐，但无恶臭，最后失水干枯而呈枯草黄色。叶柄症状与茎部同。病叶受侵处灰褐色或浅黄褐色，湿度大时亦生较稀疏的绵毛状白霉，最后病叶腐烂或干枯。该病一般在12月上中旬出现病株，1月下旬至2月上中旬是大棚中豆瓣菜菌核病的盛发期，大棚和露地均在3月上旬病情趋于稳定。在近几年的调查观察中，一直未见浅水栽植的豆瓣菜有菌核病发生，而旱地栽植的豆瓣菜，不论大棚或露地种植的条件下均可受害，并且大棚中的病情有较露地重的趋势。病茎失水干枯后，菌核极易脱落，而病茎空腔内的菌核则随病株残体遗留在土中。该病的初侵染，来自遗留在土中的菌核产生的子囊孢子。子囊孢子不能侵染健壮的枝叶，而极易侵染中下部贴近地面匍匐或半匍匐生长的衰老叶片，此后才能侵染健壮的枝叶。再侵染主要通过病患组织接触，由病部长出的绵毛状菌丝体完成。豆瓣菜的匍匐或半匍匐生长及分枝多、生长繁茂、枝叶交错的植物学性状和病原菌侵染循环特点，决定了其有利于菌核病菌的接触蔓延，而不利于子囊孢子的气流较远距离的传播，因而造成了植株中、下部枝叶发病的现象，这样就使豆瓣菜菌核病具有一定的“隐蔽性”，也导致田间病害呈点片状发生及不规则分布的特点。菌丝管状、无色，有分枝具隔膜，田间自然情况下菌丝体白色绵毛状，在病茎表面及被害茎的空腔里均可形成菌核。在测量的87个菌核中，其大小（长径）为2.0～7.0mm。菌核无休眠期。将菌核置培养皿中双层浸湿的滤纸上，13.5～16.0℃，室内散射光下培养很易萌发。一个菌核可生出一至数个子囊盘，子囊盘高足杯状，初淡褐色，后为暗褐色。柄长短因环境而异，在黑暗无光条件下，柄长可达6.0 cm以上。子囊盘中生有大量子囊和侧丝，子囊无色棒状，内生8个排列一行的子囊孢子。子囊孢子椭圆形，无色单胞，大小8.7～13.7μm×4.9～8.1μm。子囊孢子成熟后稍受震动（如打开供菌核萌发的培养皿的盖），即可看到状如烟雾的子囊孢子放射现象。据上鉴定，认为豆瓣菜菌核的分离物为Sclerotonia sclerotiorum（Lib.）de Bary。这是我们首次在豆瓣菜上发现有由核盘菌引起的菌核病。进一步研究发现该菌菌丝生长温度范围很广，其中在4～5℃时，菌落在PDA平皿上扩展速度为8.3mm/天、33℃时为2.0 mm/天、当温度达到35℃时，菌落几乎停止生长。病菌菌丝生长最适温度是21℃，在此温度下，菌落扩展速度达32.2 mm/天。

梅树炭疽病是梅树上的主要病害，在武汉地区，从4～10月份都有发生。从梅雨季节开始炭疽病开始大流行。2006～2007年8月调查，武汉地区的梅树炭疽病发病率高达97%以上。笔者从东湖梅园采集炭疽病标本。用常规组织分离法对病组织进行了分离，再进行单孢分离；采用柯赫氏法则给予回接鉴定，确认为炭疽病的病原。所有菌株均在PDA平板上于25℃下培养，并于PDA试管斜面上4 ℃保存。共分离获得22个菌株，研究发现这些菌株在菌落形态、色素分泌、产孢、孢子形态等存在显著的差异。可将这些菌株分成7种类型，其中Ⅰ型菌株：菌丝颜色为白色到灰黄色，菌丝生长较稀疏易产拟菌核和大量橘红色分生孢子团，分生孢子12.5～15μm×4.5～5.5μm；Ⅱ型菌株：菌丝颜色为灰黄色，菌落扩展速度最慢，易产生菌核不易产生分生孢子团，分生孢13.8～16μm×5～7.5μm；Ⅲ型菌株：菌丝颜色为白色较为稀疏，菌落扩展较慢，能产生大量的拟菌核和分生孢子团，菌核较Ⅰ型小且多，分生孢子15～20μm×5～6.3μm；Ⅳ型菌株：菌丝颜色为墨绿色，菌丝生长茂盛，菌落扩展最快，较少产拟菌核和分生孢子团，分生孢子12.5～13.8μm×3.8～5.5μm；Ⅴ型菌株：菌丝颜色为中间墨绿色边缘白色，菌丝生长致密气生菌丝少，菌落扩展较快，易产生大量的拟菌核但不产生分生孢子团，菌核较Ⅲ型菌核小且多，分生孢子10.5～12.5μm×3.8～5μm；Ⅵ型菌株：菌丝颜色为纯白色，菌丝生长茂密厚实，菌落扩展较快，不易产生拟菌核和分生孢子团，分生孢子18.7～22.1μm×7～10.5μm；Ⅶ菌株：菌落颜色为白色，菌丝生长密实，较Ⅵ型气生菌丝少，菌落易扇变，也不易产生拟菌核和分生孢子团，分生孢子13.8～15μm×5～7.5μm。将这7种类型菌株分别在梅树及樱树、桃树、梨树、苹果树、杏树和山楂等蔷薇科果树上的致病力进行了比较。结果表明这7种类型的菌株在这些植物上致病力存在显著的差异。其中：Ⅰ型菌株M17对上述植物的致病力最强，刺伤接种后在这些植物叶片上均能形成典型的病斑，病斑的大小因接种植物不同而略有差异，如在梅花、梨树、桃树、樱树、杏树、山楂和苹果等植物叶片上形成的病斑大小分别为：（2.7±0.2）cm、（2.5±0.2）cm、（2.3±0.2）cm、（2.1±0.2）cm、（1.9±0.2）cm、（1.9±0.2）cm和（1.3±0.2）cm；但在不刺伤的条件下，菌株M17仅能在樱树、梨树、桃树、山楂树等叶片上形成病斑。Ⅲ型菌株M11-1的致病力最弱，仅能在刺伤叶片上形成较小的病斑，如在梅花、桃树、苹果、樱树、杏树、梨树和山楂等植物叶片上形成的病斑大小分别为：（0.73±0.2）cm、（0.36±0.2）cm、（0.32±0.2）cm、（0.30±0.2）cm、（0.65±0.2）cm、（0.5±0.2）cm和（0.45±0.2）cm。所有上述菌株对吉祥草、高粱、大叶黄杨、黄瓜和豇豆等植物均不致病。利用引物对PITS1和PITS4扩增这些菌株的ITS DNA片段，连接至T-载体后，转化E.coli JM109，获得携带ITS DNA的克隆，对克隆进行测序，并在GenBank上进行Blastn序列分析。结果发现上述7个菌株的ITS序列与该数据库中的胶孢炭疽菌（Colletotrichum gloeosprioides）的ITS序列等同性在99.0%以上。因此，这些菌株应该同属于胶孢炭疽菌，但是它们在形态和致病力等方面存在显著差异。