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1.
A model system consisting of chemically isolated cuticular membranes placed on agar was used to study the penetration of various formulations of 14C-labelled clopyralid, fluroxypyr, triclopyr, picloram, and 2,4-D into and through cuticular membranes. Clopyralid, commercially formulated as the acid, or 1-decyl ester was rapidly absorbed after 12 h by isolated cuticles of Euonymus fortunei. There was less absorption of the monoethanolamine and potassium salt formulations when compared to the acid and 1-decyl ester. However, in terms of the absorbed 14C-activity that partitioned into the agar, there was no difference between the acid and salt formulations with approximately 90% being partitioned after 48 h. Conversely, the 1-decyl ester formulation of clopyralid was retained in the cuticle; less than 5% of the absorbed fraction was recovered in the agar after 48 h. When the acid forms of clopyralid, fluroxypyr, triclopyr, picloram, and 2,4-D were compared, there was little or no difference in absorption among the herbicides. However, the 14C-activity from clopyralid partitioned the most (90%) and triclopyr the least (50%) into the agar. When ester formulations of clopyralid, fluroxypyr, and triclopyr were compared, at least 95% of the 14C-activity was absorbed 24 h after application. However, of the amount absorbed, significantly more of the butoxyethyl ester of triclopyr (36%) partitioned into the agar than did the 1-decyl ester of clopyralid (6%) or the 1-methylheptyl ester of fluroxypyr (5%). Differential retention of various herbicide formulations in this model system may explain, in part, the differences in absorption and translocation among radiolabelled clopyralid formulations observed in previous research (Kloppenburg & Hall, 1990). 相似文献
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利迪链霉菌E12的发酵液对多种植物病原真菌具有较强的抑制活性。采用琼脂稀释法考察了淀粉和葡萄糖对利迪链霉菌发酵液抑菌活性的影响;采用大孔树脂吸附层析和浓缩沉淀提取发酵液中的抑菌活性物质;利用聚丙烯酰胺凝胶(SDS-PAGE)与含β-1,3-葡聚糖的琼脂糖凝胶直接反应测定粗提物的分子质量及β-1,3-葡聚糖酶活性并采用琼脂扩散法测定其抑菌活性。结果表明:当以淀粉作为惟一碳源时发酵液的抑菌率为89.2%,当以葡萄糖作为惟一碳源时发酵液无抑菌活性;在SDS-PAGE上仅出现1条大小为3 kDa左右的条带,且该条带具有抑菌活性,与其位置对应的琼脂糖凝胶上出现透明带。以上结果表明,利迪链霉菌E12可能产生一种具有β-1,3-葡聚糖酶活性的抑菌活性物质。 相似文献
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Several physicochemical factors which can influence the interactions between pest and pesticide are described. These relate mainly to the pesticides partition, reaction and diffusion processes. The combination of diffusion and partition processes in controlled release formulations is examined in some detail via theoretical consideration of encapsulated material. Extensive control of release can be obtained this way with the release time ranging from minutes to years. The advantages and disadvantages of controlled release are discussed and the relevance of theoretical considerations of this type to commercial objectives is touched upon. 相似文献
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A. P. Kole Louis Hsu Wei Tchong 《European journal of plant pathology / European Foundation for Plant Pathology》1958,64(4):297-300
Samenvatting Droge en natte zaadontsmettingsmiddelen werden respectievelijk verstoven en verspoten op strookjes filtreerpapier. Voor het bepalen van de integrale werking werd ieder strookje rechtstreeks op een voedingsbodem met een toetsschimmel gelegd; bij het bepalen van de dampwerking werd direct contact tussen het filtreerpapier en de voedingsbodem vermeden door op de voedingsbodem eerst een reepje glas en daarop het strookje filtreerpapier te leggen.Summary Two factors are of importance for the laboratory evaluation of seed dressings: the integral action consisting of the sum of the direct action by diffusion and the vapour action, and the vapour action separately. In testing seed dressings for the integral action, the fungicide is applied to filter-paper strips which are placed on the surface of potato-dextrose agar mixed with a conidial suspension of the fungusGlomerella cingulata in Petri dishes. After incubation for three days at 23°C the width of the inhibition zone along the paper strips was taken as a measure for the fungicidal action. If seed dressings have to be tested for vapour action only, direct contact between the paper strips and the agar is avoided by putting a piece of glass (one half of a slide cut lengthwise) of the size of the paper strips between these and the agar. Dusts were applied to the paper strips with an apparatus according toLoosjes (1955) and steeps with a spraying apparatus according toten Houten & Kraak (1949). The method was applied to evaluate some commercial products. 相似文献
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In studies on competition between crops and weeds it may be desirable to manipulate time of emergence, density and spatial arrangement of weeds. This requires a method to obtain a fast and uniform emergence of weeds. Two planting methods were compared that differed in the medium (agar or blotting paper) on which seeds were germinated, and in the method of transplanting the seeds (with or without the medium). In wet soil, emergence started earlier when seeds were germinated on agar and subsequently planted with agar. Root tips of seeds germinated on blotting paper may have been damaged to a greater extent during transplanting, because root tips tended to grow into the blotting paper. The duration, heterogeneity and final level of emergence were not affected by the planting method. In dry soil in a greenhouse experiment, the final level of emergence was much less when seeds were planted using the blotting paper method than when they were planted using the agar method. The agar may have provided a small source of water which reduced dehydration of emerging plants. The results were similar for the three species studies, namely, Chenopodium album L., Senecio vulgaris L. and Solanum nigrum L. 相似文献
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The effects of several nonionic surfactants on [14C]glyphosate mono(isopropylammonium) diffusion across isolated tomato fruit cuticles (Lycopersicon esculentum Mill.) were compared under controlled atmospheric conditions (25°C; 65% R.H.) using a model system consisting of 1-μl droplets applied to isolated cuticles on agar blocks. Rates of diffusion for glyphosate (10 g acid equivalent litre?1 in the applied solution) and overall amounts recovered in underlying agar blocks were influenced by the ethylene oxide (EO) chain length for a homologous nonylphenol surfactant series (10 g litre?1). Glyphosate uptake increased with EO content, reaching an optimum at a mean of 17 EO, then decreasing below control values for surfactants with 40 EO. There was a strong influence of the hydrophobe on glyphosate penetration for different surfactants with similar mean EO content (10 EO). The primary aliphatic amine enhanced penetration the most, followed by the nonylphenol while the aliphatic alcohol showed no improvement on glyphosate transfer across cuticles. Water soprtion was greatly enhanced by a primary aliphatic amine (10 EO) and by a nonylphenol (17 EO). The aliphatic alcohol (10 EO) and a shorter-chained nonylphenol (4 EO) did not significantly enhance water sorption. Comparison of water sorption with glyphosate diffusion across cuticles suggests a strong relationship between the two. Change in solution pH over a limited range had no significant effect. Promotion of cuticular hydration by surfactants may thus play an important role in the enhancement of foliar uptake of water-soluble herbicides such as glyphosate. 相似文献
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Mumtaz Alam 《Pest management science》1977,8(2):167-171
A method is described for the analysis of trace levels of hexachlorobenzene in pesticide formulations. The method involves the conversion of hexachlorobenzene to pentachlorophenol which is converted to the acetate and analysed on a gas chromatograph using microcoulometric detection. This technique allows separation of hexachlorobenzene from most constituents of the pesticide formulations. 相似文献
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玉米矮花叶病毒HC-Pro的纯化及抗血清制备 总被引：3，自引：1，他引：3
本实验提纯了玉米矮花叶病毒(MDMV)的辅助成份-蛋白酶(HC-Pro),并制备了其抗血清。MDMV HC-Pro的分子量约为57kD,提纯产量为0.3mg/100 g病叶。琼脂免疫双扩散测定证明MDMV HC-Pro抗血清的效价为1:16;微量免疫沉淀法测定时其效价为1:1024。该抗血清只与MDMV HC-Pro有明显的反应,与健康玉米汁液和MDMV无反应。MDMV HC-Pro抗血清可以专化性地抑制HC-Pro的蚜传活性。 相似文献
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ABSTRACT Fusarium oxysporum f. sp. erythroxyli is being investigated as a mycoherbicide for the narcotic plant coca. Sporulation of the fungus in seven formulations containing different organic substrates and movement of its propagules through soil were studied. The formulations were a granular wheat flour/kaolin (pesta); an extruded wheat and rice flour (C-6); and five alginate pellet products containing corn cobs, soybean hull fiber, canola meal, rice flour, or rice flour plus canola oil. Formulations were incubated at 25 degrees C for 6 weeks in desiccators with various salt solutions to provide nine relative humidities (RH), ranging from 100% (pure deionized water) to 0% (anhydrous (CaSO(4)). Hyphae of F. oxysporum f. sp. erythroxyli grew out of alginate pellets with canola meal, rice, and rice plus canola oil as early as 24 h at 100% constant RH. Alginate pellets of rice plus canola oil and granular C-6 and pesta formulations consistently produced more microconidia, macroconidia, and CFU than the other four formulations at all RH tested. The C-6 formulation produced more propagules than the other formulations at low RH (<53%). Canola meal pellets produced more spores than three other formulations when exposed to fluctuating RH (100 to 75%). The effect of percolating water on spore movement through soil was studied using a plant-pathogenic isolate of F. oxysporum f. sp. niveum. To determine the effect of water percolation on propagule movement, formulations were placed on soil columns and artificial rain was applied. In general, 10-fold fewer CFU were recovered at a 8- to 10-cm depth compared with a 0- to 2-cm depth. 相似文献
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玉米灰斑病研究方法：Ⅰ玉米灰斑病菌孢子的培养 总被引：1，自引：0，他引：1
为了明确玉米灰斑病菌的产孢条件,将玉米灰斑病菌接种到马铃薯蔗糖（PSA）、燕麦番茄碳酸钙（OTCA）、玉米叶粉碳酸钙（MLPCA）、燕麦粉（OA）、粗面粉(CWPA)等5种培养基上,于25 ℃下培养,测定该菌生长速度、产孢时间和产孢量。结果表明,菌丝在上述培养基上生长速度均较慢,每天平均生长0.33 mm左右,其中以在OA和PSA上生长速度相对较快。基于上述结果,构建了玉米灰斑病菌孢子培养的二级分段培养法,即将菌丝块接种于加有10～15粒直径为5 mm玻璃珠的马铃薯蔗糖（PS）液体培养基三角瓶里,在25 ℃,180 r/min条件下振荡培养15 d,形成菌丝悬液,再取菌丝悬浮液涂布在MLPCA 培养基上,避光培养13 d左右,可获得大量供接种的分生孢子。长期光照促进菌丝生长,不利于孢子的形成,而长期黑暗不利于菌丝生长,但有利于孢子的形成。 相似文献
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Characterizing the mechanism of biological control of postharvest diseases on fruits with a simple method to study competition for nutrients 总被引：1，自引：0，他引：1
ABSTRACT Biocontrol agents may compete with pathogens for nutrients and space to delay or prevent decay of fruits after harvest. These mechanisms of biological control have been difficult to study because no method has been available to determine the significance of each of the components of competition. We developed a nondestructive method using tissue culture plates with cylinder inserts containing defusing membrane at one end to study competition for nutrients without competition for space. Other biocontrol mechanisms in which direct contact between an antagonist and a pathogen is not required also can be studied. The method was used to determine the competition between the yeastlike biocontrol agent, Aureobasidium pullulans, and Penicillium expansum for limited nutrients in apple juice during 24 h incubation, simulating a fruit wound. The antagonist depleted amino acids and inhibited germination of P. expansum conidia. Exposing these conidia to fresh apple juice increased conidial germination to the level comparable to that exhibited by conidia which were not exposed to the antagonist. Because the culture plate method was nondestructive, follow-up experiments in an agar diffusion test were conducted. Juice in which the antagonist grew did not inhibit germination of P. expansum conidia that were seeded on the plates. This corroborates findings from the culture plate method that inhibition of the conidia germination resulted from competition for nutrients. The new method can be coupled with existing techniques to improve understanding of antagonist-pathogen interaction for biological control of postharvest diseases. 相似文献
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首次尝试将羧甲基壳聚糖与改性膨润土复合用作除草剂莠去津的载体,制备得到控释型颗粒剂,以延缓莠去津的释放,减少淋溶损失,提高药效及控制其污染。通过水中释放实验研究了制剂配方对莠去津释放速率的影响,并借助半经验方程探讨了其释放机理,采用土壤薄层实验考察了复合载体对降低莠去津淋溶的效果。 结果表明,采用复合载体时莠去津的半数释放时间(t 50)可达700 h 以上,比对照采用单一羧甲基壳聚糖作载体时延长了1倍以上。莠去津由颗粒剂向水相释放的过程主要受费克扩散(Fickian diffusion)控制,且经9次淋洗后莠去津的累计淋出率仅为6.0%,表明该复合载体控释制剂可显著减少莠去津对地下水的污染。 相似文献
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建立了一种测定6类液体农药制剂中烷基酚（alkylphenols,APs）及其聚氧乙烯醚类（alkylphenol ethoxylates,APEOs）助剂的高效液相色谱-荧光分析方法。乳油、水剂、水乳剂、悬浮剂、可溶液剂和微乳剂样品均经甲醇超声辅助提取,稀释后过聚丙烯膜,采用Poroshell 120 EC-C18（4.6 mm×100 mm,2.7 μm）分离,V（甲醇）:V（乙腈）:V（水）=75.5:6.5:18.0三元流动相等度洗脱,荧光检测器检测,外标法定量。结果表明:在0.05~10或0.1~20 mg/L范围内,APs和APEOs的峰面积与其质量浓度间呈良好线性关系（R2均大于0.999 8）;在添加水平范围内（APs:0.5、2、5 mg/g;APEOs:1、5、25、50 mg/g）,6类液体农药剂型中APs和APEOs的平均回收率为73%~110%,相对标准偏差为0.6%~14.9%,方法的定量限在0.5~1 mg/g。该方法简单、快速、准确,适用于不同液体农药制剂中烷基酚及其聚氧乙烯醚类助剂的测定。 相似文献
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Germling development by Erysiphe graminis f. sp. hordei was compared between conidia held in a simulated air-borne state on microthreads constructed from safety-line threads produced by orb--weaving spiders (Araneus diadematus), and conidia inoculated onto glass, agar, or living or dead barley coleoptile epidermes. Suspended conidia germinated but generally produced only multiple short germ tubes. Conidia on living or dead coleoptiles, bathed from beneath with 0.01
Ca(NO3)2 solution, generally produced one short germ tube and a second germ tube which elongated and formed a normal appressorium. On glass and agar, multiple short germ tubes were sometimes formed but long germ tubes were formed less frequently than on host epidermis. When conidia with short germ tubes were transferred from microthreads to coleoptiles, they produced a long germ tube which differentiated an appressorium. Conidia with a single short germ tube were also transferred from microthreads so that only the tip of the short germ tube was in contact with a leaf epidermal strip layed on agar, whilst the conidium rested on the agar. Long germ tubes were formed more frequently by such conidia than by controls which had no contact with the leaf epidermis. This suggested that a stimulus causing elongation of the second tube was perceived through the short germ tube in contact with the epidermal strip. Where long germ tubes made contact with the epidermal strip, normal appressoria were formed more frequently than where the long tube made contact with the agar surface alone. The results indicate that germlings develop through distinct stages in response to particular stimuli. 相似文献
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防治杨树溃疡病内生菌的分离筛选及鉴定 总被引：6，自引：4，他引：2
为筛选到对杨树溃疡病有良好生防效果的拮抗菌,采用平板对峙法初筛、发酵液“三明治”法和改良琼脂扩散法复筛,以及离体组织试验对杨树不同部位组织的内生菌进行了分离筛选,并对目的菌株进行了防治效果测定;采用形态学观察和ITS序列及其系统发育树分析对其进行初步鉴定。结果表明从115株杨树内生菌中筛选出有拮抗效果的菌株24株,并复筛出拮抗效果良好的菌株5株,最终从杨树内生菌中筛选出1株杨树溃疡病拮抗真菌,编号为YGF9,其对杨树离体组织溃疡病防治效果可达76.47%,初步鉴定该菌株为黄绿木霉Trichoderma aureoviride。表明菌株YGF9可有效抑制杨树溃疡病病原菌的生长,是防治杨树溃疡病的潜在生防菌株。 相似文献
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烟草疫霉是重要的病原真菌,但在人工培养条件下难以培养、产孢以及释放游动孢子.作者对烟草疫霉培养、产孢、接种方法进行了研究.芝麻培养基、黑麦培养基、燕麦培养基可用来培养烟草疫霉,烟草疫霉在三种培养基上平均每天生长量为1.10、0.78、0.86cm;芝麻培养基、黑麦培养基为烟草疫霉产孢子囊较好的培养基,产孢能力强,分别为2.52×104、2.07×104个孢子囊/cm2.而且孢子囊释放率高,分别为43.0%、32.1%.游动孢子囊悬浮液灌根接种和注射接种都能使烟草发病,但不同的接种方法和接种浓度下,病情指数不同. 相似文献