Adsorption of systemic pesticides on ground stems and in the apoplastic pathway of stems,as related to lignification and lipophilicity of the pesticides

The adsorption of five systemic fungicides (carbendazim, triadimefon, nuarimol, triarimol, and fenarimol) and one herbicide (fluometuron) on ground stems and in the apoplastic pathway of excised pepper, cotton, and bean stems was studied. Adsorption on ground and water extracted stems, as well as retention in the apoplast of excised stems, increased with the 1-octanol/water partition coefficients of the pesticides. Methylation of ground stems increased their adsorption capacity (carbendazim excluded), while extraction with organic solvents did not affect it. Woody stems adsorbed more of the pesticides than herbaceous ones. Binding of pesticides in the apoplastic pathway of stems seems to be related to their degree of lignification and to the lipophilicity of the pesticides.     

Adsorption of systemic fungicides and a herbicide by some components of plant tissues,in relation to some physicochemical properties of the pesticides

Lignin, an important component of plant tissues, adsorbed five systemic fungicides and one herbicide (carbendazim, triadimefon, nuarimol, triarimol, fenarimol and fluometuron) more strongly than bovine serum albumin, cellulose, ethylcellulose or sodium polygalacturonate. Significant correlations were found between the extent of the adsorption of the pesticides on the lignins extracted from three different plant species, and the log Poet (Poet is the octan-1-ol/water partition coefficient) of the compounds. The more lipophilic fungicides triarimol and fenarimol (log Poet about 2.6) were adsorbed to the greatest extent. Fluometuron, triadimefon and nuarimol (log Poet about 2.0) were moderately adsorbed, whereas carbendazim with the lowest log Poet (1.34 at pH 5.0), was adsorbed more than expected from its Poet value. The anomaly of carbendazim is discussed; it is ascribed to it's partial protonation at pH 5.0, whereas the other pesticides were non-ionised.     

Metabolism of some sterol inhibitors in fungi and higher plants,with special reference to the selectivity of fungicidal action

The metabolism of triforine, chloraniformethan, the α-(pyrimidin-5-yl)benzhydryl alcohols (fenarimol, nuarimol and triarimol), the trityl-azoles (fluotrimazole and clotrimazole), and the morpholine types of sterol inhibitors is reviewed; the metabolism of the azolyl-alkane derivatives (mainly triadimefon and triadimenol) is discussed in detail. Redox and hydrolytic reactions are of primary importance. Enzymic inactivation may be one factor influencing fungicide selectivity. Metabolism is the dominant factor of selectivity if it represents the activation process, as with triadimefon. Transformations in higher plants do not differ significantly from those occurring in fungi, except that factors such as the formation of conjugates with natural compounds of plant tissues also play a role, as with triforine and triadimenol. The selectivity of fungitoxic action may be influenced by metabolism both in the host plant and the pathogen.     

Similarities between the systemic fungicides triforine and triarimol

The fungicides triforine and triarimol, though structurally unrelated have a similar antifungal spectrum. Neither fungicide inhibited germination of conidia of Cladosporium cucumerinum, but both inhibited subsequent mycelial growth. Triforine, like triarimol, proved to be an effective inhibitor of ergosterol biosynthesis. Two mutants of C. cucumerinum selected for resistance to triarimol also exhibited resistance to triforine and to the triarimol analogues ancymidol and bis(4-chlorophenyl)-3-pyrimidinemethanol. Resistance of these mutants, however, did not extend to the sterol inhibitors triparanol and trans-clomiphene or to sodium o-phenylphenate and 2,6-dichloro-4-nitroaniline, two compounds usually tolerated by fungi exhibiting general hydrocarbon resistance. Toxicity of either triforine or triarimol to C. cucumerinum was annuled by β-carotene, vitamin A, progesterone, testosterone and farnesol. The various similarities between triforine and triarimol suggest a common mode of action for the two compounds.     

Soil application of azadirachtin and 3-tigloyl-azadirachtol to control western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae): translocation and persistence in bean plants

To study the systemic effects of active neem ingredients, the substrate of bean plants was treated with a 170 g kg(-1) azadirachtin (NeemAzal-U; Trifolio-M GmbH, Lahnau, Germany, registration pending). This product was used at a dose rate of 10 mg AZA (azadirachtin a) and 1.2 mg 3-tigloyl-azadirachtol (azadirachtin b) per treated bean plant. Afterwards, the translocation and persistence of AZA and 3-tigloyl-azadirachtol and the effects on western flower thrips, Frankliniella occidentalis (Pergande), were studied. Residues of AZA and 3-tigloyl-azadirachtol from substrates with different contents of organic matter [pure culture substrate (CS), CS-sand mixture] and from various plant parts were quantified by high-performance liquid chromatography-mass spectrometry (HPLC-MS). The dissipation trends of AZA and 3-tigloyl-azadirachtol were similar within the same substrates. A slower decline of both active ingredients was measured with CS than with CS-sand mixture. Residue analysis of the bean plants showed that only small proportions of the initial amounts of AZA and 3-tigloyl-azadirachtol applied to the substrate were present in the plant (0.3-8.1%). Variable amounts of residues of the active components in relation to plant parts and time of analysis indicated a different translocation pattern for the two active ingredients. Higher residues of the active ingredients were found in roots and stems after neem application using CS, whereas higher residues were found in leaves after CS-sand mixture treatments. Mortality of F. occidentalis after NeemAzal-U soil applications reached up to 95% on CS-sand mixture, compared with 86% in CS.     

Study of Bacterial Determinants Involved in the Induction of Systemic Resistance in Bean by Pseudomonas putida BTP1

The ability of Pseudomonas putida BTP1 to induce resistance in bean to Botrytis cinerea was demonstrated in soil experiments on plants pre-inoculated at the root level with the bacteria before challenge with the leaf pathogen. As a first step to characterize the molecules from BTP1 responsible for induction of systemic resistance in bean, heat-killed cells and supernatant from culture in an iron-limited medium were tested for their protective effect. Most of the resistance-eliciting activity of the strain was retained in the crude cell-free culture fluid. In vivo assays with samples from successive fractionation steps of the BTP1 supernatant led, (i) to the conclusion that salicylic acid, pyochelin and pyoverdin, previously identified as Pseudomonas determinants for induced systemic resistance (ISR), were not involved in systemic resistance triggered by BTP1, and (ii) to the isolation of fractions containing one main metabolite that retained most of the resistance-inducing activity in bean. Although this molecule remains to be structurally characterized, its isolation is an addition to the range of determinants from plant growth-promoting rhizobacteria (PGPR) known to stimulate plant defences.     

Leaf Spot Disease of Broad Bean (vicia faba L.) Caused by Alternaria tenuissima— A New Disease in Japan

Farmers' fields were surveyed for a new disease on broad bean in different parts of Shimane Prefecture. The disease was found in all surveyed fields. The fungus frequently associated with diseased broad bean leaves having the characteristic leaf spot symptom was identified as Alternaria tenuissima, based on morphological characteristics. The initial lesion was brown, water soaked, circular to slightly irregular. Then the lesion enlarged and became concentric. Mature leaves had coalescing necrosis surrounded by yellowing. Older leaves of the plant were particularly affected. In a later stage of the disease, the leaves became blighted from the margin to the center and most of the diseased plants defoliated. In severely infected fields, circular to irregularly shaped lesions also appeared on stems and pods, and plants defoliated completely. All tested isolates were pathogenic to broad bean leaves. Different isolates of the fungus varied in pathogenicity on different broad bean cultivars. In a comparison of symptoms of the disease and morphological characteristics of the isolated fungus with other broad bean diseases, this disease represented a new, as yet undescribed disease of broad bean in Japan. Therefore, we propose the name "leaf spot of broad bean" and "Soramame hanten-by?" in Japanese. Received 12 April 2001/ Accepted in revised form 18 October 2001     

土壤湿度对蚕豆根病及其生长的影响

 土壤湿度是影响蚕豆(Vicia faba L.)生长和根腐病发生的主要环境因素之一。本文以来源于蚕豆产区的田间土壤,分别以30%、50%和70%的土壤饱和持水量(WHC)处理进行盆栽试验,在室外自然条件下生长,测定了出苗率、出苗速度、株高、生长速度、叶面积、总叶绿素含量、净光合速率、结荚数、根瘤数、生物量干重、根腐病严重度及死亡率。结果表明50% WHC的土壤含水量为蚕豆生长的最佳土壤湿度,有利于蚕豆健康生长,减少根腐病的发生与危害。在30%、50%和70%WHC土壤湿度条件下,播后10周蚕豆生物量干重和植株的死亡率依次分别为1.53、3.16、2.68g和18.5%、4.8%、25.6%。     

Resistance to triforine: A nonexistent problem?

Permanent resistance to triforine in Cladosporium cucumerinum was obtained after UV irradiation of spore suspensions and selection of resistant strains in the presence of triarimol or triforine. About 50 strains were examined for mycelial growth on malt agar, viability upon routine subculturing, growth and inhibition by triforine in thin-layer chromatographic bioassays, and virulence towards cucumber seedlings. In addition, sporulation and spore germination, as well as effects of ergosterol were investigated in a restricted number of strains. Although all strains differed considerably from each other in these characteristics, they were quite similar in a reduced overall-fitness. These triforine-resistant mutants of C. cucumerinum might, therefore, have a greatly reduced chance of survival in competition with the wild-type strain, as was actually demonstrated for two strains in greenhouse experiments with mixed-inoculations of cucumber seedlings. Such a reduced chance of survival might also explain why under practical conditions development of resistance to triforine has not been observed yet.The triforine-resistant C. cucumerinum strains showed cross-resistance to a number of systemic fungicides known or supposed to inhibit ergosterol biosynthesis, viz. Denmert, fenarimol, imazalil, triadimefon and triarimol. The practical implications and potential hazards of such cross-resistance for the use of already established fungicides are discussed.     

Electrophoretic and serological comparisons of pathogenesis-related (b) proteins from different plant species

Preparations of pathogenesis-related (b) proteins (PRs) from differentNicotiana species, tomato,Gynura aurantiaca, bean, and cowpea were compared to each other and to bean chitinase and a constitutive apple agglutinin by electrophoresis in polyacrylamide gels both in the absence and in the presence of SDS, and by serological double diffusion analysis using antisera against tobacco PRs and bean chitinase. PRs from different plant genera displayed a similar but not identical range of relative mobilities in both native and SDS gels, whereas bean chitinase and apple agglutinin were clearly different. None of the antisera reacted with any of the PR preparations from plant genera other than the one from which the antigen(s) had been derived. Whilst PRs within the genusNicotiana are serologically related and can be identical, PRs from different plant genera seem to be sufficiently different to be considered as genus-specific.     

植物生长调节剂DTA-6在甜豌豆上的应用效果

以美国菜用甜豌豆“甜脆蜜”为试验材料, 研究了植物生长调节剂DTA 26 对甜豌豆产量和品质的影响。结果表明,DTA 26 处理能: 1) 显著提高甜碗豆单株生产能力, 单位面积产量均高于清水对照; 2) 提高了根系还原力和叶片叶绿素含量; 3) 使甜豌豆主要营养成分如可溶性糖、可溶性蛋白、游离氨基酸的含量均有提高。DTA 26 处理菜用甜豌豆可使产量和品质协同提高。     

菜豆种子普通细菌性疫病菌检测

 由Xanthomonas axonopodis pv. phaseoli和Xanthomonas fuscans subsp. fuscans引起的菜豆普通细菌性疫病是严重影响菜豆生产的限制因子之一,可造成严重的产量和品种损失。染菌种子是病原菌传播的主要途径。本研究对5个菜豆主要产区的60份菜豆种子样品进行普通细菌性疫病菌检测。在MT选择性培养基上有36份种子样品浸提液检测到目标病原菌, 种子样品带菌量为2.49×10²~5.20×10⁷ CFU/粒。选择36个分离物接种感病品种“英国红”植株,所有分离物均引起接种植株发病。特异PCR检测结果表明,有20个分离物为X. fuscans subsp. fuscans,16个分离物为X. axonopodis pv. phaseoli。试验结果表明,我国一些菜豆主产区商业种植和研究用种子多数污染普通细菌性疫病菌,建议建立无菌种子生产区和加强种子管理,以有效控制病害发生。     

基于连续14年国家绿豆品种区域试验的中国绿豆品种产量和性状变化

利用GGE双标图、变异系数法、相关性分析、多元回归和聚类分析等方法,分析了2003—2016年共14 a国家绿豆品种区域试验中来自内蒙古自治区、黑龙江省、吉林省、辽宁省、山西省等12个绿豆主产省（市、自治区）的29个育种单位提供的130个参试品种的生育天数、株高、主茎节数、主茎分枝数、荚长、单株荚数、荚粒数、千粒重以及产量在春播组和夏播组的变异,并比较了性状间的相关性以及不同育种单位选育的绿豆品种的性状差异。结果表明：2003—2016年春播组和夏播组绿豆产量分别增加14.0%和25.4%,年均增幅分别为1.0%和1.8%;主茎分支数分别减少12.0%和15.9%;其他性状变化不明显。春播组绿豆主要农艺性状的变异系数为5.14%~17.01%,均值为11.33%;遗传多样性指数为1.91~2.08,平均为1.99。夏播组绿豆主要农艺性状的变异系数为5.96%~19.99%,均值为12.52%;遗传多样性指数为1.98~2.17,平均为2.07。相关性和偏相关性分析表明,春播组中产量与荚长、单株荚数和荚粒数显著正相关,与其他性状的相关性不明显;夏播组中产量与单株荚数和荚粒数显著正相关,与株高、主茎分支数和荚长显著负相关。多元回归分析表明,春播组绿豆生育天数、株高、主茎分支数、荚长和单株荚数共同决定产量60.9%的变异;夏播组绿豆株高、主茎分枝数、单株荚数、荚粒数和千粒重共同决定产量87.7%的变异。依托品种选育区域的聚类分析表明,65个春播组品种被分为4类,在北京市、河北省、山西省、河南省、山东省、吉林省和陕西省综合表现较好;65个夏播组品种被分为6类,在河南省、河北省和山东省综合表现较好。2003—2016年,国家每轮区试的绿豆品种产量稳步提升,表明我国绿豆育种水平有了一定提升;但品种遗传基础狭窄,育种方法多样化程度较低,缺少突破性品种。     

一种蚜虫持久性传病的长豇豆黄化型病毒

 1983年6月,在南京郊区的长豇豆上采到1株表现植株矮缩症状的C-7病毒分离物。接种试验证明,它不能摩擦接种传病,但可以由豆蚜(Aphis craccivora)、棉蚜(A.gossypii)和桃蚜(Myzus persicae)以持久性方式传病。寄主范围测定的结果表明:分离物可以侵染长豇豆、豇豆、蚕豆、大豆、菜豆、豌豆、赤豆、利马豆、苜蓿、红三叶、地三叶、绛三叶、葫芦巴,紫云英和苕子等15种豆科植物和曼陀罗1种茄科植物。这些植物大都出现植株矮化,叶片扭曲,卷缩或僵缩,不能开花结实等症状。豆蚜的传病性状中,获毒饲育的最短传病时间为3小时,接毒饲育最短传病时间为10分钟,循回期是24小时左右。但是,传病率最高的获毒饲育时间是2~3天,接毒饲育时间在1天以上。接种1头蚜虫就具有传病能力,5头蚜虫能达到100%的传病率。蚜虫可以终身传毒,蜕皮不影响其传毒力,但传毒有间歇性。根据它的基本性状,病毒C-7分离物是一种豆科植物的黄化型病毒,可能是属于大麦黄矮病毒组(Luteovirus Group)的成员。     

Screening faba bean for chocolate spot resistance: evaluation methods and effects of age of host tissue and temperature

Chocolate spot is an important disease of faba bean (Vicia faba) caused by the necrotrophic fungus Botrytis fabae. The aims of this work were: i) to compare different methods of screening for resistance; ii) to assess the influence of the age of host tissue and temperature on this pathosystem. To this effect, a collection of 42 faba bean accessions was evaluated in mature plant stage in the field in Cordoba (Southern Spain) and in detached leaflet and whole plant tests under controlled conditions. Field results correlated better with those of the whole plant test than with those of the detached leaflet assay. Integration of results from the field and whole plant experiments resulted in the selection of six accessions of interest as sources of resistance. Influence of leaf age on disease development was found to be genotype dependent. Older leaves were more susceptible than younger ones in 23 accessions, while no difference between leaf ages was detected in the remaining accessions. The effects of plant age and temperature were assessed by a whole plant test on seven accessions at two plant ages (4 and 7 weeks) and three temperatures (13, 20, and 25°C). Results showed that the differential genotypic responses to B. fabae were not significantly influenced by either plant age or temperature, although there was a tendency towards lower susceptibility to chocolate spot in faba bean plants as they become older. Further, a partial high-temperature, young-plant resistance was detected.     

Fungitoxicity and growth regulation involving aspects of lipid biosynthesis

Triarimol and triforine inhibit ergosterol biosynthesis in fungi and cause accumulation of free fatty acids, 24-methylenedihydrolanosterol, obtusifoliol and 14α-methyl-δ^8,24(28)-ergostadienol. Triparanol also inhibits ergosterol synthesis and causes accumulation of free fatty acids, but not of the latter 3 sterols. Triparanol appears to inhibit prior to lanosterol in the sterol biosynthetic pathway of Ustilago maydis and at unidentified sites subsequent to lanosterol which lead to the accumulation of a sterol which migrates with desmethylsterols on TLC plates. Quantitative abnormalities in sterols and free fatty acids in U. maydis are not produced by the fungicides carbendazim, chloroneb, carboxin and cycloheximide. A deficiency in nitrogen leads to a marked increase in triglycerides, but a normal distribution pattern for other lipids.Inhibition of oxidative demethylation of the sterol 14α-methyl group is probably the prime mechanism of inhibition of ergosterol biosynthesis by triarimol. Rates of formation of obtusifoliol and 14α-methyl-δ^8,24(28)-ergostadienol in triarimol-treated U. maydis cells suggest that C-4 demethylation occurs along an abnormal pathway which operates effectively only at high substrate concentrations. The growth retardant action of triarimol and ancymidol in higher plants most likely results from inhibition of a reaction in the gibberellin biosynthetic pathway analogous to sterol C-14 demethylation.Free fatty acid accumulation in U. maydis cells treated with inhibitors of sterol synthesis are derived mainly from polar lipid degradation and from de novo synthesis as a consequence of the disproportionality between fatty acid synthesis and utilization. The free fatty acids may play a significant role in the lethality of these inhibitors in this organism.     

Some physicochemical factors influencing foliar uptake enhancement of glyphosatemono(isopropylammonium) by polyoxyethylene surfactants

Structure-concentration–foliar uptake enhancement relationships between commercial polyoxyethylene primary aliphatic alcohol (A), nonylphenol (NP), primary aliphatic amine (AM) surfactants and the herbicide glyphosatemono(isopropylammonium) were studied in experiments with wheat (Triticum aestivum L.) and field bean (Vicia faba L.) plants growing under controlled-environment conditions. Candidate surfactants had mean molar ethylene oxide (EO) contents ranging from 5 to 20 and were added at concentrations varying from 0·2 to 10 g litre^?-1 to [¹⁴C]glyphosate formulations in acetone–water. Rates and total amounts of herbicide uptake from c. 0·2–μl droplet applications of formulations to leaves were influenced by surfactant EO content, surfactant hydrophobe composition, surfactant concentration, glyphosate concentration and plant species, in a complex manner. Surfactant effects were most pronounced at 0·5 g acid equivalent (a.e.) glyphosate litre^?-1 where, for both target species, surfactants of high EO content (15–20) were most effective at enhancing herbicide uptake: surfactants of lower EO content (5–10) frequently reduced, or failed to improve, glyphosate absorption. Whereas, at optimal EO content, AM surfactants caused greatest uptake enhancement on wheat, A surfactants gave the best overall performance on field bean; NP surfactants were generally the least efficient class of adjuvants on both species. Threshold concentrations of surfactants needed to increase glyphosate uptake were much higher in field bean than wheat (c. 2 g litre^?-1 and < 1 g litre^?-1, respectively); less herbicide was taken up by both species at high AM surfactant concentrations. At 5 and 10 g a.e. glyphosate litre^?-1, there were substantial increases in herbicide absorption and surfactant addition could cause effects on uptake that were different from those observed at lower herbicide doses. In particular, the influence of EO content on glyphosate uptake was now much less marked in both species, especially with AM surfactants. The fundamental importance of glyphosate concentration for its uptake was further emphasised by experiments using formulations with constant a.i./surfactant weight ratios. Any increased foliar penetration resulting from inclusion of surfactants in 0·5 g litre^?-1 [¹⁴C]glyphosate formulations gave concomitant increases in the amounts of radiolabel that were translocated away from the site of application. At these low herbicide doses, translocation of absorbed [¹⁴C]glyphosate in wheat was c. twice that in field bean; surfactant addition to the formulation did not increase the proportion transported in wheat but substantially enhanced it in field bean.     

黄瓜炭疽病菌对杀菌剂的敏感性的优化测定方法研究

本文以黄瓜炭疽病菌(GloeosporiumorbiculareArs)为研究对象,采用随机试验设计,比较了不同培养基、孢子萌发方法对病菌孢子萌发的影响,建立了一套测定炭疽病菌分生孢子对杀菌剂敏感性的简易方法。结果表明:不同培养基培养的分生孢子,均以使用玻片水琼胶表面萌发法的萌发效果最好,且以PDA培养基培养的分生孢子在玻片水琼胶表面萌发率最高、最稳定。此外使用该方法测定了黄瓜炭疽病菌对福美双、百菌清的敏感性。     

菜豆普通细菌性疫病菌在土壤和植株残体中的越冬能力

为评估菜豆普通细菌性疫病菌地毯草黄单胞杆菌菜豆致病变种或褐色黄单胞菌褐色亚种在土壤及植物残体中的越冬能力,对采自黑龙江、内蒙古、山西、河北及新疆的18块菜豆生产田的20份土壤及14份植物残体样品进行病原菌分离和鉴定。在MT选择性培养基上有12个土壤样品和13个植株残体样品提取液产生典型的类似黄单胞菌菌落。选取29个分离物进行致病性测定,有27个分离物对菜豆品种"英国红"致病。利用地毯草黄单胞杆菌菜豆致病变种和褐色黄单胞菌褐色亚种的特异性引物X4c/X4e及褐色黄单胞菌褐色亚种特异性引物Xf1/Xf2对29个分离物进行多重PCR检测,其中17个分离物为地毯草黄单胞杆菌菜豆致病变种,10个分离物为褐色黄单胞菌褐色亚种。结果表明,菜豆普通细菌性疫病菌可以在黑龙江、内蒙古、山西、河北的一些菜豆种植区的土壤及植株残体中越冬存活。     

豆科功能植物作为东亚小花蝽产卵基质的适合度评价

东亚小花蝽Orius sauteri (Poppius)作为一种重要的捕食性天敌,被广泛用于多种温室害虫的防控。由于该天敌具有在植物组织内产卵的特殊习性,其卵的发育离不开植物,导致筛选适宜的产卵基质植物一直是其规模繁育的重要基础。豆科植物不仅可以作为绿肥和保护型生物防治的功能植物,而且还可以作为东亚小花蝽的适宜产卵基质。因此,本研究以产卵量、产卵持续时间、卵孵化时间、卵孵化率及净生殖力等为指标,在实验室内评价了豇豆、菜豆、大豆、豌豆、绿豆和花生6种豆科植物作为东亚小花蝽产卵基质的适合度。结果表明：东亚小花蝽在绿豆上的总产卵量和净生殖力最高,分别为72.0粒和59.5头,显著高于菜豆、大豆和花生;卵孵化率最高的是花生,为86.79%,但与绿豆并无显著差异;东亚小花蝽在6种植物上的产卵持续时间无显著差异,在绿豆上卵的孵化时间最短,显著低于菜豆和花生。东亚小花蝽在绿豆上的产卵位置也优于其他植物,所以综合考虑绿豆为所试6种植物中东亚小花蝽的最适产卵基质植物。