Histology of Sclerotium cepivorum infection of onion roots and the spatial relationships of pectinases in the infection process

Sclerotium cepivorum (isolate Sc4) hyphae penetrated the epidermis and hypodermis of onion roots and grew into the cortex. Immediately following penetration only the cells through which S. cepivorum grew were lysed, but subsequently cells were killed and cell walls disintegrated ahead of the infection hyphae. Sclerotium cepivorum produced two polygalacturonases (PG) and two pectinesterases (PE) in culture. These isozymes were also found in infected onion root tissues and another PG and a PE were occasionally detected. Two isozymes of PG and three isozymes of PE diffused ahead of the infection hyphae. The spatial distribution of these enzymes was associated with cell death and cell wall degradation. The epidermis, hypodermis, endodermis and vascular tissues were more resistant to hydrolysis than the cortex, but only the endodermis and cells within it retained nuclei following hydrolysis of the surrounding cortical tissues. The cavity within the root cortex became filled with swollen, vacuolate S. cepivorum hyphae.     

翻面法培养白绢病菌菌核的研究

采用翻面法对白喙病菌最适培养基的最、最佳翻面的时机等进行了研究,结果表明：翻面法的最适培养基使用量,以每个直径为８５ｍｍ培养皿使用２０ｍｌ为佳,培养的菌核数量多,成熟度一致;翻面时机为菌丝长满平板时最佳,形成的菌核数量多,成熟快。     

Influence of soil type and indigenous pathogenic fungi on bean hypocotyl rot caused by Rhizoctonia solani AG4 HGI in Cuba

Calcisol, ferralsol and vertisol soils, representative of different bean production areas of Villa Clara province in Cuba, were selected to determine the impact of soil type on bean hypocotyl rot severity caused by Rhizoctonia solani AG4 HGI (isolate CuVC-Rs7). In inoculated autoclaved soil, hypocotyl rot was most severe in calcisol soil, followed by ferralsol soils and then vertisol soils. In inoculated natural soils, disease severity was lower in vertisol and calcisol soils and higher in ferralsol soil, indicating that biological factors are suppressing or stimulating the pathogenic efficiency of R. solani. Native binucleate Rhizoctonia AGF, Sclerotium rolfsii and R. solani AG 4 HGI were isolated from bean plants grown in natural calcisol, vertisol and ferralsol soils, respectively. Subsequent studies about the interaction between these fungi and R. solani indicated that they were involved in the variability of disease severity caused by R. solani. The addition of R. solani AG4 HGI (isolate CuVC-Rs7) into each autoclaved soil inoculated with binucleate Rhizoctonia or S. rolfsii resulted in a reduction of disease severity caused by this pathogen while in soils inoculated with native R. solani AG4 HGI, disease severity increased. Irrespective of fungal interactions, calcisol was always the most disease conducive soil and vertisol the most disease repressive soil. The mechanisms by which native pathogenic fungi could influence disease severity caused by R. solani are discussed.     

宜油系列油菜品种对菌核病的抗性鉴定与评价

[目的]为宜油系列油菜品种推广利用提供理论依据。[方法]对宜油系列油菜品种进行田间施放菌核、自然诱发鉴定试验。[结果]结果表明,宜油系列油菜品种间抗菌核病能力有明显的差异。所鉴定的6个宜油品种中,宜油13号表现为高抗菌核病,宜油15中抗菌核病,宜油11号、宜油12号低抗菌核病,宜油9号、宜油10号低感菌核病。宜油13号和宜油15在抗菌核病和产量方面都表现出明显的优势。[结论]宜油13号、宜油15有较强的抗菌核病能力和高产性能,具有较大的推广潜力,适宜四川及类似生态区域推广种植。     

Effect of sewage sludge on suppressiveness to soil-borne plant pathogens

The objective of this study was to evaluate the effect of sewage sludge on soil suppressiveness to the pathogens Fusarium oxysporum f. sp. lycopersici on tomato, Sclerotium rolfsii on bean, Sclerotinia sclerotiorum on tomato, Rhizoctonia solani on radish, Pythium spp. on cucumber, and Ralstonia solanacearum on tomato. Soil samples were collected from an experimental corn field in which sewage sludge had been incorporated once a year, since 1999. Sludge from two sewage treatment stations in Brazil (Franca and Barueri, SP) were applied at the rates of one (1N), two (2N), four (4N) and eight (8N) times the N recommended doses for the corn crop. Soil suppressiveness was evaluated by methods using indicator host plants, baits and mycelial growth. There was no effect of sewage sludge on soil suppressiveness to Fusarium oxysporum f. sp. lycopersici in tomato plants. For S. rolfsii, reduction of the disease in bean was inversely proportional to the dose of Franca sludge. The incidence of dead plants, caused by S. sclerotiorum, was directly proportional to sludge doses applied. For R. solani and R. solanacearum, there was a linear trend with reduction in plant death in soils treated with increasing amounts of sludge from Franca. There was an increase in the pathogen community of Pythium spp., proportional to the amounts of sewage applied. The effects of sewage sludge varied depending on the pathogen, methodology applied and on the time interval between the sewage sludge incorporation and soil sampling.     

双曲孢菌(Nakataea Sigmoidea Hara)生物学特性初步研究

报道了东北地区水稻小球菌核菌无性世代的分生孢子－双曲孢属（Nakataea sigmoidae Hara)，并对其人工培养条件进行了初步的探讨，结果表明，自然光照能促进该菌产生分生孢子，在自然光条件下，病原菌在水琼脂培养基上产生分生孢子，生长物质和微量元素均不能促进孢子产生，碳氮比对菌核萌发直接产生分生孢子有影响，其中10：1时产孢率最高，为54．23％。     

羊肚菌产核条件研究

对羊肚菌(Morchella spp.)的两个重要菌株在不同温度、不同培养皿大小、不同碳源、不同氮源、不同微量元素以及不同浓度的KH2PO4和MgSO4、不同酸碱度等实验条件下进行了室内培养菌株最佳产核条件的研究，并观察不同种的菌株在培养皿上菌株产核的阶段性表现以及菌核培养特征。实验结果表明：供试菌株A在15℃～20℃、菌株B在20℃～25℃恒温条件下，pH值在5～7范围内产核最好；营养方面两菌株能利用多种碳、氮源，其中以葡萄粮或蔗糖作为碳源，以酵母粉或蛋白胨作为氮源最佳；另外，两菌株对微量元素的需求不明显，而KH2PO4和MgSO4对菌株产核却有重要作用；培养皿则以采用9.0cm规格的产核早且多。     

非洲桃花心木苗叶斑病研究初报

非洲桃花心木苗叶斑病研究初报李云，骆土寿关键词非洲桃花心木苗，叶斑病，咖啡生小核菌，药剂防治非洲桃花心木（ＫｈａｙａｓｅｎｅｇａｌｅｎｓｉｓＡ．Ｊｕｓｓ．）是著名的热带速生珍贵用材树种和优良的行道及庭园绿化树种。非洲桃花心木苗病害过去有过调查报道，但...     

Application of an emulsifiable mixture of 1,3-dichloropropene and chloropicrin against root knot nematodes and soilborne fungi for greenhouse tomatoes in Italy

A mixture of 1,3-dicloropropene 60.5% w/w and chloropicrin 33.3% w/w (Telone C35 EC) may be registered in Italy for soil drip fumigation. Five experiments on greenhouse tomatoes in Northern, Central and Southern Italy compared the effectiveness of this mixture in comparison with methyl bromide to find the optimum application rate in soils infested by Fusarium oxysporum f.sp. lycopersici, F. oxysporum f.sp. radicis lycopersici, Sclerotium rolfsii, Meloidogyne javanica and M. incognita. Its efficacy against F. oxysporum f.sp. radicis lycopersici and M. incognita was confirmed when applied to soils at 100, 200, 300 and 400 l ha⁻¹ (132.4, 268.4, 402.6 and 536.8 kg ha⁻¹) under gas-tight films with 15–45 mm of application water (900–1200 mg Telone C35 EC l⁻¹). In sandy soils, with slight F. radicis lycopersici infections and with heavy nematode (M. incognita) attacks, the mixture, drip applied at 900 mg l⁻¹ during late summer (fumigation: late summer; transplant: late-summer/autumn; last harvest: early spring), performed well up to 132.4 kg ha⁻¹ (100 l ha⁻¹). In sandy loam soils with slight F. radicis lycopersici infections and severe infections of F. lycopersici and galling nematodes (M. javanica), 268.4 kg ha⁻¹ (200 l ha⁻¹) of the mixture applied at 900 mg l⁻¹ as a drip provided yields similar to those of methyl bromide treated plots both in spring and summer cycles. In sandy loam soils, the diseases (F. lycopersici, F. radicis lycopersici) were controlled at rates 268.4 kg ha⁻¹ (containing 90 kg ha⁻¹ of chloropicrin), but the mixture was ineffective against Sclerotium rolfsii occasionally observed in sandy loam soils. In both sandy and sandy loam soils, no significant relationships were found between the rates of mixture applied (132.4, 268.4, 402.6 and 536.8 kg ha⁻¹) and the degree of nematode infestation.     

微生物菌剂拌种对花生土传病害的防治效果及产量影响

为探索微生物菌剂拌种防治花生根部病害的防治效果及对产量的影响,以鲁花8号为试验材料,选择3个微生物菌制剂和1个化学药剂,设置1000亿CFU/mL解淀粉芽胞杆菌、200亿CFU/mL多粘类芽胞杆菌、1亿CFU/g真菌生防菌（TB）、1000亿CFU/mL解淀粉芽胞杆菌+1亿CFU/g真菌生防菌（TB）、200亿CFU/mL多粘类芽胞杆菌+1亿CFU/g真菌生防菌（TB）和25%咯菌腈拌种处理进行田间药效试验。结果表明： 6种供试药剂拌种处理均对花生有一定的增产作用,且对根腐病和白绢病均有一定的控制效果,其中1000亿CFU/mL解淀粉芽胞杆菌+1亿CFU/g真菌生防菌（TB）种子处理的出苗率、增产率和综合防效最高,其出苗率和增产率分别为94.35%和23.15%;出苗30 d后根腐病防效为76.95%,出苗60 d后根腐病和白绢病防效分别为83.54%和83.88%,在绿色防控技术推广应用中具有良好的应用前景。