降香黄檀叶枯病菌的鉴定及其生物学特性

近年来,降香黄檀叶枯病的危害越来越严重,为深入了解该病菌特征,本研究对该病原菌进行鉴定,以期为制定更有效的防治措施提供依据。本研究对降香黄檀叶枯病病株进行病原菌分离,并对病原菌进行了形态学观察及rDNA-ITS序列测定,确定该病原菌为天门冬拟茎点霉菌[Phomopsis asparagi (Sacc.) Bubak]。通过观察该病原菌在不同培养基、温度、pH、光照等4种环境因素中的生长情况,发现该病原菌在马铃薯果糖琼脂培养基（PFA）中菌丝生长最快;菌丝在10~30 ℃均能生长,最适宜的生长温度为25~30 ℃;最适宜的pH为6;光照对该病原菌的生长没有显著影响。     

海南桑树青枯病病原菌鉴定及其分子鉴定

桑树青枯病是由青枯雷尔氏菌引起的细菌性病害,热带、亚热带地区发病严重,严重影响蚕桑产业的可持续发展。雷尔氏菌不同种间致病力和宿主各不相同,其防治策略也相应不同,准确地分离鉴定病原菌是青枯病有效防控的先决条件。本研究采集、分离了海南省琼中县桑青枯病发病桑园（‘桂桑优62’）桑树根部、茎部病原菌,并通过致病性、生理小种、生化变种测定,结合16S rDNA、特异性引物、复合PCR检测体系、序列变种等分子鉴定方法初步确定了病原菌的种类和分类地位。结果表明,引发海南省琼中县桑青枯病的病原菌属于青枯雷尔氏菌（Ralstonia solanacearum）、生理小种5（race 5）、生化变种Ⅴ（biovar Ⅴ）,病原菌遗传进化分析结果显示病原菌属演化型Ⅰ（phylotype Ⅰ）即亚洲分支菌株,序列变种12（sequevar 12）。这些结果将为海南桑青枯病的有效防控奠定基础。     

木麻黄红根病病原菌鉴定及其生物学特性测定

对引起木麻黄红根病的病原菌进行鉴定,并测定该病原菌的生物学特性。结果表明:致病性测定接种后木麻黄罹病症状与田间症状相似,根据病原菌子实体形态、显微结构和ITS序列分析,确定引起木麻黄红根病病原菌为热带灵芝[Ganoderma tropicum(Jungh.)Bres.]。病原菌生物学特性测定结果表明:光照对菌丝生长有抑制作用;菌丝生长的最适宜温度为30℃,最适p H值为6.0;在以大豆蛋白胨为氮源的培养基中生长最好,最适碳源为蔗糖。     

香茅草挥发物及其主要成分对3种茶树病原真菌的抑制性研究

采用固相微萃取和气相-质谱联用仪检测了香茅草鲜草茎和叶的挥发成分,分析确定了香茅草鲜草茎和叶中共51种挥发成分,主要成分为柠檬醛[包含(E)-柠檬醛与(Z)-柠檬醛]和香叶醇,茎中相对含量分别为81.39%(58.48%和22.91%)和4.79%;叶片中相对含量分别为78.50%(51.63%和26.87%)和3.68%。采用菌丝生长速率法,研究了柠檬醛和香叶醇分别对茶树炭疽病病原菌(Colletotrichum gloeosporioides)、轮斑病病原菌(Pestalotiopsis theae)、褐芽病病原菌(Phoma adianticola)的抑制活性。活性初测结果表明,500 mg·L^-1处理96 h,两种成分对供试轮斑病病原菌抑制率均低于56%;而对供试茶炭疽病和褐芽病病原菌的抑制率均可达100%。进一步活性测试结果表明,柠檬醛对茶炭疽病和褐芽病病原菌的抑制中浓度(EC₅₀)值分别为(230.56±3.49) mg·L^-1和(124.79±10.29) mg·L^-1;香叶醇对两种病原菌的EC₅₀值分别为(238.38±5.51) mg·L^-1和(115.38±10.96) mg·L^-1。本研究初步明确了香茅草鲜草挥发成分及其对茶树病害病原菌抑制活性的主要物质基础,为茶园种植香茅草具有潜在防病害作用提供了理论依据。     

红毛丹炭疽病菌生物学特性研究

对红毛丹炭疽病病菌进行分离,鉴定病原菌为胶孢炭疽菌[Colletotrichum gloeosporioides(Penz.)Sacc.]。研究培养基、温度、湿度、pH值、光照、营养对红毛丹炭疽病菌生长和孢子萌发的影响。结果表明,该菌菌丝在PDA、CA和CZ培养基上生长较好,10~35℃下均能生长,适宜生长温度为25~28℃,分生孢子萌发的最适温度为28℃;病原菌在pH3~11都能生长,pH5~8生长较好,菌丝生长及孢子萌发最佳pH值为7;分生孢子在饱和湿度中萌发快,相对湿度低于99%时不能萌发;光照对病原菌的生长有明显的促进作用,病原菌的致死温度为:55℃,10min;PDA培养基中加入不同的糖对病原菌生长有明显的促进作用,以鼠李糖、果糖、半乳糖、麦芽糖、甘露糖和木糖最好;PDA培养基中添加2%的不同的无机氮源对病原菌的生长有明显的促进作用。     

甜瓜棒孢叶斑病病原菌鉴定及其生物学特性研究

对海南三亚发生的甜瓜棒孢叶斑病的危害症状进行了系统的描述,采用致病性试验、形态学观察及分子生物学的方法对引起该病的病原菌进行了鉴定,同时采用菌落生长法和玻片法测定了病原菌的生物学特性。结果表明：甜瓜棒孢叶斑病的病原菌为多主棒孢霉[Corynespora cassiicola（Berk. & Curst.）Wei];病原菌菌丝生长的最适宜培养基为大豆培养基,最适温度为 24~28 ℃,致死温度和时间为55 ℃、15 min,最适pH为 8~10,光照有利于菌丝生长,最适碳源为乳糖,最适氮源为NaNO3;分生孢子萌发的最适温度为 24 ℃,致死温度和时间为50 ℃、20 min。     

油梨根腐病病原菌的鉴定、生物学特性及室内药剂筛选

根腐病是油梨的毁灭性病害之一,该病害为害根部,引起根部变黑腐烂,严重时导致植株死亡。从发病典型的植株根部分离、纯化菌株,并开展致病性测定、形态学特征和多基因位点（ITS、LSU和COXⅡ）系统发育树分析相结合的病原菌鉴定。结果表明,引起海南油梨根腐病的病原菌为樟疫霉（Phytophthora cinnamomi）。还研究了不同培养条件和10种药剂对病原菌菌丝生长的影响。结果表明,病原菌在PDA培养基上生长较好,最适生长温度为28 ℃,最适pH为8,黑暗条件更适合病原菌的生长;烯酰吗啉对病原菌的抑制作用最强,EC₅₀为0.0929 μg/mL。本研究结果为油梨根腐病的田间防控提供了一定的理论依据。     

一种火龙果腐烂病病原菌鉴定及生物学特性研究

对火龙果腐烂病的病原进行鉴定,并对其病原菌的生物学特性进行分析研究。结果表明:该病原菌为双间柱顶孢[Scytalidium dimidiatum(Penz.)Sutton and Dyko],生长最适温度为30℃,生长最适pH为7,病原菌生长的最佳碳源是棉子糖、葡萄糖、蔗糖,最佳氮源是硫酸铵、蛋白胨;连续光照有利于病菌生长。病原菌的致死温度为75℃,时间为10 min。     

芒果树回枯病病原菌鉴定及其生物学特性研究

对芒果树回枯病病原菌进行鉴定,并对该病病原菌进行生物学特性测定。结果表明：引起芒果树回枯病的病原菌为可可球二孢菌（Botryodiplodia theobromae Pat.）。该菌菌丝最适生长温度为28～32 ℃,致死温度为60 ℃、10 min,最适pH值5～9;菌丝生长最佳碳源为蔗糖,木糖不适于该菌生长;最佳氮源是蛋白胨;全光照有利于该菌生长。     

胡椒瘟病病原菌对12种杀菌剂的敏感性测定

采用生长速率法测定了胡椒瘟病病原菌对常用的12种杀菌剂的敏感性。试验结果表明，胡椒瘟病病原菌对不同供试杀菌剂的敏感性存在明显差异，其中69　%烯酰吗啉·锰锌WP、25　%甲霜·霜霉WP、50 %烯酰吗啉WP和36 %霜休锰锌WP对病原菌的抑菌效果好且敏感性高，EC50分别为1.862　1、1.129 8、3.419 8和6.309 6　μg/mL；50 %琥铜甲霜WP次之。     

西瓜细菌性果斑病症状描述和病原菌鉴定

描述了近年来海南省乐东、东方等县西瓜种植区发生的一种细菌性病害在西瓜果实和叶片上的危害症状,测定了病原菌的形态、染色反应、培养性状、生理生化特性和寄主范围,将病原菌鉴定为Ａｃｉｄｏｖｏｒａｘ ａｖｅｎａｅ ｓｕｂｓｐ．ｃｉｔｒｕｌｌｉ（ｓｃｈａａｄ,ｅｔ ａｌ．）ｗｉｌｌｅｍｓ,ｅｔ ａｌ．     

水稻细菌性谷枯病病原菌的分离鉴定

经多年的病原菌分离监测, 于2006年从2份浙江省稻种(来自海南的健康籼稻)上分离到6株病原细菌,经25项主要生理生化特性、菌落形态、致病性、Biolog、脂肪酸分析和RAPD PCR鉴定,发现这种病原细菌为Burkholderia glumae, 是引起水稻细菌性谷枯病的病原菌。此外,实验证明“健康稻种”也可能存在水稻细菌性谷枯病菌。     

Isolation and Identification of Burkholderia glumae from Symptomless Rice Seeds

A survey on isolation and detection of the casual organism of bacterial grain rot of rice was conducted during 1997–2006. In 2006, six pathogenic bacterial strains were isolated from two symptomless seed samples of rice (Oryza sativa L.) originally produced in Hainan Province and then planted in Zhejiang Province, China. They were identified as Burkholderia glumae which is the causal organism of bacterial grain rot of rice by physiological characteristics, colony morphology, pathogenicity test, Biolog, fatt...     

红掌细菌性叶枯病的症状和病原菌鉴定

描述了近年来海南省琼山、儋州等市红掌栽培地发生的一种细菌性叶枯病的症状，测定了病原菌的形态、染色反应、培养性状、生理生化特性、寄主范围以及血清学反应，将病原菌鉴定为菇假单胞菌红掌致病变种（Pseudomonas agarici Young pv.anthurii）。     

湖北恩施马铃薯一种新记录病害

在湖北恩施从马铃薯上采集到一种叶斑病，病原菌鉴定为Ｍｙｃｏｖｅｌｏｓｉｅｌａ（Ｃｅｒ－ｃｏｓｐｏｒａ）ｃｏｎｃｏｒｓ（Ｃａｓｐ．）Ｄｅｉｇｈｔｏｎ，经文献检索该病害为湖北省内新记录。初步调查，马铃薯灰斑病（Ｍ．ｃｏｎｃｏｒｓ）在个别品种上零星发生。     

茶树嫩叶上的“白馒头”——茶饼病

茶饼病是真菌病害,可为害茶树嫩叶、茎和果实,主要发生在嫩叶上。文章介绍了茶饼病的分布与为害、病原菌生物学特征、流行规律和防治措施,以期为生产上该病的正确识别和有效防治提供参考。     

Evaluation of flusulfamide for the control of bacterial ring rot of potato

The potential of flusulfamide (2’, 4-dichloro- α, α, α, trifluoro-4’-nitro-m-toluenesulfonanilide) as a control agent for bacterial ring rot of potato was evaluated by testing the bactericidal activity of this compound against the causal agent,Clavibacter michiganensis subsp.sepedonicus inin vitro tests, followed by greenhouse and field trials involving treatment of inoculated seed tubers. In thein vitro tests, significant reduction in the size and number ofC. m. sepedonicus colonies was observed with complete inhibition of growth occurring at flusulfamide concentrations of 100 mg/1 or greater. In the greenhouse and field trials, tubers of potato cultivar Russet Burbank were inoculated with the causal organism of bacterial ring rot,C. m. sepedonicus, in one of three different ways (cutting, dipping, injection) and subsequently treated by dipping in an aqueous solution containing varying concentrations of flusulfamide. The “dip” and “cut” methods of inoculation were intended to simulate transmission that would occur during normal production practices, while the “inject” treatment was intended to assess the effect of flusulfamide on existing infections. In both the greenhouse and field experiments, foliar disease incidence and infection rates were reduced, but not eliminated, in plants that were inoculated by cutting or dipping and treated with flusulfamide, whereas plants that had been inoculated by injection showed little effect of treatment with flusulfamide. Based on the results of these experiments, flusulfamide appears to have protective rather than curative properties againstClavibacter michiganensis subsp.sepedonicus.     

Management of Cephaleuros parasiticaus Karst (Trentepohliales: Trentepohliaceae), an algal pathogen of tea plant,Camellia sinsensis (L) (O. Kuntze)

The efficacy of certain biocontrol agents were evaluated against Cephaleuros parasiticus Karst, a causal organism of red rust disease in tea plants. Spraying of systemic fungicides was found to be superior to biocontrol agents followed by algicides in controlling the disease under field condition. Dipping of shears in the solutions of fungicide, detergent or biocontrol agents failed to protect the disease spread. The study on the impact of different harvesting practices on disease development showed the highest disease incidence in continuously shear harvested fields and least in hand plucked fields. There was a reduction in disease incidence in spraying of a solution containing urea and murate of potash mixture at 1% level. The maximum green leaf yield and productivity index were recorded in biocontrol agents treated plots. Among the various group of biocontrol agents evaluated, Streptomyces sannanensis and Streptomyces griseus belong to actinomycetes was better than bacterial and fungal antagonists in terms of disease protection and increase in yield potential. Similarly, tea bush canopy architecture, physiological and biochemical parameters were also increased in plants treated with biocontrol agents. In the case of untreated control plots, the disease incidence was increased from 36% to 44.5% and the plants were found unhealthy in terms of chlorosis, stunted growth and heavy flowering with banji buds. The shoots collected from treated and untreated control plots were subjected to manufacture CTC black tea which revealed almost all the tea quality parameters were significantly improved in the treated plot over the untreated plots.     

Reducing the potential for bacterial soft rot in potato tubers by chemical treatments and drying

The potential for bacterial soft rot caused byErwinia carotovora in freshly inoculated potato tubers was reduced up to 99% by immersion for 5 min in solutions of sodium hypochlorite (chlorine bleach) containing up to 10,000 ppm chlorine. Reductions up to 93% were achieved using a combination treatment of immersion in 1% citric acid for 5 min followed by airdrying. Immersion treatment alone in 1% aqueous solutions of citric, acetic, ascorbic, or malonic acid also significantly reduced the soft rot potential. In contrast, no reductions accompanied treatment with solutions of potassium or calcium acetate. All treatments including the combination immersion/airdrying treatment were much less effective if tubers had been infiltrated initially with soft rotErwinia or had numerous mechanical injuries. If tubers had not been infiltrated with the causal organism, immersing them in 1% citric acid reduced the potential nearly as much as a similar treatment with 1000 ppm chlorine. A 30-sec immersion in the latter was less effective than a similar treatment with 500 ppm a.i. CGA 78039, an experimental bactericide. However, air-drying, coupled with provisions for keeping tuber surfaces free from moisture, remains the most effective means of reducing losses to bacterial soft rot.     

Bacterial top rot: a new disease of the potato

Summary ‘Top rot’, a new bacterial disease of potato was found to occur in India. Water-soaked lesions developed on succulent stems, petioles and leaves. On stems and petioles the lesions enlarged into stripes turning black, which ultimately enveloped the affected portion and caused a soft rot, resulting in toppling of the stem/leaf. The affected tissues were covered with whitish bacterial exudates under high humidity but became dried and shrivelled under dry conditions. Leaflet infection occurred through infected petioles, via mid-rib and veins, or through the margins, resulting in rotting and blighting. The bacterium also caused soft rot of tubers. The disease was favoured by high humidity and a temperature range of 25–30°C. The causal bacterium was identified asErwinia carotovora var.carotovora.