An Aqueous Extract of the Dry Mycelium of Penicillium chrysogenum Induces Resistance in Several Crops under Controlled and Field Conditions

We have examined the effect of Pen, an aqueous extract of the dry mycelium of Penicillium chrysogenum, on plant–pathogen interactions. Pen controlled a broad range of pathogens on several crop plants under greenhouse and field conditions. Pen protected grapevine from downy and powdery mildew (caused by Plasmopara viticola and Uncinula necator), tomato from early blight (caused by Phytophthora infestans), onion from downy mildew (Peronospora destructor) and apple trees from apple scab (caused by Venturia inaequalis) to a similar extent as fungicides such as copper and sulphur or well-known inducers such as benzothiadiazole or β-aminobutyric acid. Pen had no major direct fungicidal effect and is thus supposed to protect plants by activating their defense mechanisms. The raw material for extraction of Pen was available in constant quality, a prerequisite for commercial application. Under certain conditions, Pen caused phytotoxic side effects. The symptoms mostly consisted of small necrotic spots or, more rarely, of larger necrotic areas. The development of the symptoms was dependent on several parameters, including concentration of Pen, the number of applications, the persistence on the plant tissue, the plant species and variety and environmental conditions. In grapevine, a partially purified fraction of Pen was much less toxic than the crude Pen extract, but protected the plants to a similar extent against P. viticola. Our data show that Pen has interesting and unique properties as a plant protection agent, but more research is needed to further reduce its phytotoxic side effects.     

安徽省烟草黑胫病菌的交配型及其地理分布研究

 Total 69 isolates of Phytophthora nicotianae var. nicotianae were isolated and identified from tobacco black shank samples collected from different areas of Anhui province, and mating types of the oomycete were investigated by the method of partnership culture in vitro on L-tryptophan medium with β-sitosterol. The results showed that A2 mating type was the predominant in isolates of P. nicotianae var. nicotianae, next was A₀ mating type, A₁ and other mating types were not observed. It was suggested that sexual reproduction of P. nicotianae var. nicotianae might not take place frequently, and Anhui province might not be the original center of P. nicotianae var. nicotianae. The results indicated further that mating type geographical distribution of P. nicotianae var. nicotianae in Anhui province was in line with that in China. In addition, the significance of the test results and the possible reason for A₁ mating type being absent were discussed.     

西葫芦根腐病病原的鉴定

通过对所采集的西葫芦根腐病病株进行分离培养,共得到5种病原菌,分属于疫霉菌Phytophthora和镰刀菌Fusarium2个属。经致病性测定,确定引起西葫芦根腐病的主要致病菌为疫霉菌,镰刀菌对西葫芦根腐病的发生有加重作用。经鉴定该致病疫霉菌为烟草疫霉菌(Phytophthora nicotanae),主要致病镰刀菌为尖孢镰刀菌(Fusarium oxysporum)。     

Pathogenicity and RAPD analysis of Phytophthora nicotianae pathogenic to pepper in Tunisia

Nine isolates of Phtophthora nicotianae were isolated from infected pepper plants. Their pathogenicity was studied in Capsicum annuum in comparison with P. nicotianae isolates from tomato and tobacco. The pathogenicity test showed that pepper isolates of P. nicotianae are adapted to their host. Banding patterns obtained by RAPD analysis with six oligonucleotide primers revealed polymorphism that grouped the isolates independently of the plant host. The polygenic dendrogram showed that pepper isolates were more similar to tomato isolates than to tobacco isolates. The RAPD bands of 1300 and 1500 bp, detected with primers OPD-01 and OPD-10, respectively, appeared specific to the most pathogenic pepper isolates. The OPK-08-1950 seems specific to the isolates of P. nicotianae from tomato. These results suggest that host specified might occur in P. nicotianae and that may be due to interspecific hybridization events resulting in novel pathogenic behavior.     

甲霜灵·刺复配剂对棉疫病菌的联合毒力

在实验室条件下，测定了甲霜灵和霜霉威复配剂对棉疫病菌（Phytophthora boehmeriae）的联合毒力。结果表明，复配剂MPA、MPB、MPC对棉疫病菌的DC5。分别为0．0555,0．1044μg／mL和0．0845μg／mL，对照单剂甲霜灵和霜霉威对棉疫病菌的EC50分别为0．0391μg／mL和10．6183μg／mL；联合毒力分析表明，甲霜灵和霜霉威按1：1．5复配有增效作用，按1：1和1．5：1复配有相减作用。     

Phytophthora boehmeriae boll rot: a new threat to cotton cultivation in the mediterranean region

A boll rot of cotton (Gossypium hirsutum L.) was observed for the first time in Greece in August 1993 in Larissa and Volos counties, and in August and September 1995 in Trikala and Phthiotis counties. Fungi of the genusPhytophthora were isolated from diseased plants. Morphological characteristics of the pathogen were recorded on mounts made directly from the infected tissues or after growth of the isolated fungus on corn meal agar or sterile distilled water. Colony morphology, growth rates, features of asexual and sexual structures and maximum growth temperatures were examined. APhytophthora species new to Europe,Phytophthora boehmeriae Sawada, attacking cotton bolls, was identified. The pathogenicity of the isolates was confirmed by artificial inoculations of detached cotton bolls. Analysis of α-esterase isozymes revealed unique banding patterns for isolates ofP. boehmeriae compared with those ofP. cactorum andP. parasitica, which arePhytophthora species with similar morphology.     

苎麻疫霉对棉苗致病力的遗传与变异研究

 以分离自江苏省棉铃疫病病组织的苎麻疫霉(Phytophthora boehmeriae Sawada)野生型菌株JS-5为亲本,采用菌丝块创伤接种法测定了苎麻疫霉对棉苗致病力在游动孢子无性系和卵孢子后代的遗传。结果表明,苎麻疫霉对棉苗的致病力在单游动孢子无性系连续两代稳定遗传,而在单卵孢第1代(OG₁)则发生连续性变异。从OG₁中选致病力强、弱2个单卵孢株为亲本,分别建立单卵孢第2代(OG₂)和单游动孢子无性系,并测定其对棉苗的致病力。结果为上述2个单卵孢株的游动孢子后代对棉苗的致病力均与其各自亲本相似,而在它们的单卵孢株群体(即OG₂)中对棉苗的致病力继续发生复杂的连续性变异。上述结果表明,苎麻疫霉对棉苗的致病力可能由细胞核杂合多基因控制。     

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。