Metabolism of amitrole in apple: II. Bound residues from mature fruits

Significant radioactivity detected in mature fruits, harvested from apple trees (Malus domestica Borkh., cv. ‘Golden Delicious’ and ‘Gloster’) that were soiltreated with [3,5-¹⁴C]amitrole, remained in the insoluble plant material after exhaustive extraction. These bound residues were solubilized with a mixture of pectinases and cellulases. Thus, separation and characterization of carbohydrates and xenobiotic moieties released during this procedure became possible. A part of the radiolabel was incorporated into natural products, indicating degradation of the applied amitrole and reassimilation of [¹⁴C] carbon dioxide.     

Differential inhibition of potassium ion absorption by difenzoquat in wild oat and cereals

Over a concentration range of 5.0 × 10^?6?7.5 × 10^?4M, the selective herbicide difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) caused more pronounced inhibition of potassium ion (K⁺) absorption by excised seedling roots of susceptible wild oat (Avena fatua L.) compared to those of tolerant barley (Hordeum vulgare L. cv. Bonanza) or wheat (Triticum aestivum L. cv. Neepawa). At 2.5 × 10^?5M difenzoquat, the relative inhibition of K⁺ (⁸⁶Rb) absorption by wild oat root segments inceased from 30% with a 10-min uptake period to 75% with an uptake period of 90 min, whereas no inhibition at all was evident for wheat root segments even after a 90-min exposure to the herbicide. An ion efflux compartmental analysis procedure demonstrated that difenzoquat did not affect the passive permeability properties of the plasma membrane of wild oat root cells. The experimental findings indicated that difenzoquat interfered directly with the process of active ion transport across the plasma membrane of root cells.     

Reduced rates of residual and post-emergence herbicides for weed control in vineyards

In 1997 and 1998, five field studies were conducted at four Portuguese wine‐growing regions in order to evaluate the effectiveness of the chemical control of vineyard weeds under Mediterranean conditions using either reduced doses of residual herbicides or only foliar herbicides. Amitrole (3440 g a.i. ha^?1), amitrole + glyphosate mono‐ammonium salt (1720 + 900 g a.i. ha^?1), amitrole (3400 g a.i. ha^?1), amitrole + diuron (2580 + 1500 g a.i. ha^?1), amitrole + simazine (2580 + 1500 g a.i. ha^?1), amitrole + terbuthylazine (2580 + 1500 g a.i. ha^?1) and amitrole + diuron + simazine (2580 + 1300 + 1400 g a.i. ha^?1) were assayed and compared with the following reference herbicides: glyphosate isopropylamine salt (1800 g a.i. ha^?1), amitrole + diuron (2520 + 1680 g a.i. ha^?1), diuron + glyphosate + terbuthylazine (1275 + 900 + 1425 g a.i. ha^?1), amitrole + simazine (1900 + 3900 g a.i. ha^?1) and glyphosate + simazine (800 + 2200 g a.i. ha^?1). The herbicides were applied during late winter. The results indicated that good control was achieved by the application of foliar herbicides alone or of reduced rates of a mixture of residual herbicides with foliar herbicides for at least 2 months. Three months after application, the efficacy of post‐emergence herbicides and lower rates of residual herbicides decreased significantly in clay soils and under heavy rainfall conditions. Convolvulus arvensis– a weed that is becoming increasingly significant in Portuguese vineyards – was poorly controlled, even when glyphosate was used. Despite this, it can be assumed that in those regions in which the trials were conducted, it is possible to employ weed control strategies that entail the elimination or a reduction in the rate of residual herbicides.     

Metabolism of the herbicide glufosinate‐ammonium in plant cell cultures of transgenic (rhizomania‐resistant) and non‐transgenic sugarbeet (Beta vulgaris), carrot (Daucus carota), purple foxglove (Digitalis purpurea) and thorn apple (Datura stramonium)

The metabolism of the herbicide glufosinate‐ammonium was investigated in heterotrophic cell suspension and callus cultures of transgenic (bar‐gene) and non‐transgenic sugarbeet (Beta vulgaris). Similar studies were performed with suspensions of carrot (Daucus carota), purple foxglove (Digitalis purpurea) and thorn apple (Datura stramonium). ¹⁴C‐labelled chemicals were the (racemic) glufosinate, L ‐glufosinate, and D ‐glufosinate, as well as the metabolites N‐acetyl L ‐glufosinate and 3‐(hydroxymethylphosphinyl)propionic acid (MPP). Cellular absorption was generally low, but depended noticeably on plant species, substance and enantiomer. Portions of non‐extractable residues ranged from 0.1% to 1.2% of applied ¹⁴C. Amounts of soluble metabolites resulting from glufosinate or L ‐glufosinate were between 0.0% and 26.7% of absorbed ¹⁴C in non‐transgenic cultures and 28.2% and 59.9% in transgenic sugarbeet. D ‐Glufosinate, MPP and N‐acetyl L ‐glufosinate proved to be stable. The main metabolite in transgenic sugarbeet was N‐acetyl L ‐glufosinate, besides traces of MPP and 4‐(hydroxymethylphosphinyl)butanoic acid (MPB). In non‐transgenic sugarbeet, glufosinate was transformed to a limited extent to MPP and trace amounts of MPB. In carrot, D stramonium and D purpurea, MPP was also the main product; MPB was identified as a further trace metabolite in D stramonium and D purpurea. © 2001 Society of Chemical Industry     

Note: Comparison of three laboratory methods to evaluate the pathogenicity and virulence of tenPseudomonas syringae pv.syringae strains on apple, pear, cherry and peach trees

The pathogenicity and virulence of ten GreekPseudomonas syringae pv.syringae strains from different hosts (citrus, pear, apple, peach and cherry) were evaluated using three different laboratory methods, which produced results in good agreement. All ten strains were virulent on apple, pear, cherry and peach trees. The extent of tissue colonized varied considerably among strains and cultivars. On excised shoots and twigs of apple and pear, strains BPI 176, BPI 203, PI 2 and PI 14 were the most virulent and strains BPI 689, BPI 992, BPI 4, BPI 20, PI 18 and PI 19 were the least virulent. On excised shoots and twigs of peach and cherry, strains BPI 176, BPI 203, PI 2, PI 14, PI 18 and PI 19 were the most virulent and strains BPI 4 and BPI 20 were the least virulent. Moderate virulence was evinced by strains BPI 689 and BPI 992. These pathogenicity assays are proposed as rapid and reproducible screening systems to evaluate the susceptibility of apple, pear, cherry and peach cultivars to this bacterial pathogen.     

Partial purification and properties of an esterase from tomato cell suspension cultures hydrolysing the pyrethroid insecticide cyfluthrin

An esterase which hydrolyses the pyrethroid insecticide cyfluthrin, was isolated from tomato cell suspension cultures and purified 10-fold. The apparent molecular weight of the enzyme was estimated to be 32 000 Dalton, the pH-optimum 8-0, and the temperature optimum 35°C. The esterase showed a low substrate specificity and hydrolysed certain esters, e. g. ethyl 4-nitrobenzoate, p-nitrophenyl acetate and dinoseb acetate, whereas ethyl butyrate and the organophosphates demeton-S-methyl sulfoxide and paraoxon could not be hydrolysed. Because of the additional strong inhibition of the enzyme by these organophosphates the cyfluthrin hydrolase is suggested to belong to the B-esterase type. An apparent K_m-value of 6-25 × 10^?4 mol litre^?1 was obtained for p-nitrophenyl acetate as substrate.     

Inhibition of fatty acid biosynthesis in isolated bean and maize chloroplasts by herbicidal phenoxy-phenoxypropionic acid derivatives and structurally related compounds

The effects of nine phenoxy-phenoxypropionic acid derivatives and structurally related compounds on the incorporation of [¹⁴C]-acetate into free fatty acids in isolated bean and maize chloroplasts were studied. The compounds tested were esters and the corresponding free acids, OH-diclofop, a nonherbicidal metabolite of diclofop in plants, and d and l enantiomers of diclofop. Fatty acid biosynthesis in bean chloroplasts was not affected by all compounds. OH-Diclofop had a weak inhibitory effect on fatty acid synthesis in maize chloroplasts, while free acids were stronger inhibitors than the corresponding esters in the same system. Uptake studies with diclofop-methyl and diclofop indicated that the esters showed higher uptake rates in chloroplasts suspension. d-Diclofop (I₅₀, 9 × 10^?8M) was a more potent inhibitor than l-diclofop (I₅₀, 4 × 10^?6M). This agrees with the low herbicidal activity of the l enantiomer in vivo. The results suggest that the mode of action in this type of herbicide may be closely linked with the inhibition of fatty acid biosynthesis. The tolerance of beans could be based on an insensitivity of the target site.     

Herbicide and inhibitor effects on cell leakage in suspension cultures of tobacco (Nicotiana tabacum)

Effects of selected herbicides and respiratory inhibitors on leakage from tobacco (Nicotiana tabacum) cell suspension cultures were studied. Leakage was monitored by quantitation of fluorescein dye released from preloaded cells and by measuring conductivity changes in the suspension medium. The herbicides ioxynil, Barban, 2,4,5-T, MCPB, and PCP (10^?6 to 10^?4M) caused leakage of fluorescein dye and electrolytes within 2 hr of exposure to the herbicides. Potassium cyanide and 2,4-DNP caused appreciable leakage at the same concentrations. Similar responses were induced by anaerobiosis. Atrazine, metolachlor, paraquat, and nitrofen did not induce leakage when tested at concentrations of 10^?6 to 10^?4M.     

Persistence and activity of mexacarbate and its metabolites against spruce budworm larvae

This study was conducted to determine if metabolites of mexacarbate contribute to its residual toxicity to spruce budworm (Choristoneura fumiferana) larvae. Potted white spruce (Picea glauca) trees were treated with ‘Zectran’ UCZF # 19 at 100 g a.i. ha^?1 and kept in a glasshouse. Mexacarbate residues declined by 98–99% within three days and reached non-detectable levels 10 days after treatment. Mortality of larvae fed on buds from these trees declined more gradually and was still 19–27% when exposed 10 days after treatment. The very low levels of mexacarbate (<0.07 μg g^?1) found after three days did not produce such mortality. Gas chromatographic analysis of metabolites in needles revealed that after three days, 4-methylformamido-3,5-xylyl N-methylcarbamate was present at levels 20–30 times higher than the parent compound. This metabolite was about 50 times less toxic than mexacarbate to larvae when applied topically but was only 7 times less toxic when ingested. Two other methylcarbamate metabolites, the amino, and methylamino analogues were detectable for one day following treatment but not at later time points. They were as toxic as mexacarbate both topically and orally. Based on these findings, the methylformamido analogue could contribute to the residual toxicity of mexacarbate treatments of spruce.     

<Emphasis Type="Italic">Alternaria alternata</Emphasis> apple pathotype (<Emphasis Type="Italic">A. mali</Emphasis>) causes black spot of European pear

A disease caused by Alternaria alternata occurred on the leaves of European pear cultivar Le Lectier in Niigata Prefecture, Japan, and was named black spot of European pear. In conidial inoculation tests, the causal pathogen induced not only small black lesions on the leaves of European pear cultivar Le Lectier, but severe lesions on the leaves of apple cultivar Red Gold, which is susceptible to the A. alternata apple pathotype (previously called A. mali) causing Alternaria blotch of apple. Interestingly, the apple pathotype isolate showed the same pathogenicity as the European pear pathogen. HPLC analysis of the culture filtrates revealed that A. alternata causing black spot of European pear produced AM-toxin I, known as a host-specific toxin of the A. alternata apple pathotype. AM-toxin I induced veinal necrosis on leaves of Le Lectier and General Leclerc cultivars, both susceptible to the European pear pathogen, at 5?×?10^?7 M and 10^?6 M respectively, but did not affect leaves of resistant cultivars at 10^?4 M. PCR analysis with primers that specifically amplify the AM-toxin synthetase gene detected the product of expected size in the pathogen. These results indicate that A. alternata causing black spot of European pear is identical to that causing Alternaria blotch of apple. This is the first report of European pear disease caused by the A. alternata apple pathotype. This study provides a multiplex PCR protocol, which could serve as a useful tool, for the epidemiological survey of these two diseases in European pear and apple orchards.     

Spray retention and distribution on apple trees

Total deposits and their distribution on bush and dwarf hedgerow apple trees, sprayed at the late dormant and full foliage stages with a copper fungicide by five different methods, were estimated by colorimetric determination of the acid-extracted copper from all the tree parts, and for comparison purposes were converted to equivalent volumes retained. The bush trees were sprayed by hand lance (4500 litresha-¹), by automatic nozzle mast sprayer (2250 litres ha^?1), by conventional air-blast sprayer at medium volume (1125 litres ha^?1) and low volume (560 litres ha^?1), and by hand-directed ultra-low-volume (ULVH) fan-assisted spinning-disc sprayer (6 litres ha^?1). The hedgerow trees were sprayed by conventional air-blast sprayer at low volume (560 litres ha^?1) and by an experimental tractor-mounted ultra-low-volume air-blast sprayer (45 litres ha^?1). At the late dormant stage, the bush trees retained only 9–22 % of the total spray applied by all methods, except that those sprayed by the hand-directed ULVH sprayer retained 57%. At the full foliage stage, when most of the spray was deposited on the leaves, retention for all methods of application was 22–37%. The hedgerow trees at late dormancy retained 6% of the spray applied in low volume and 10% of that by tractor-mounted ultra-low-volume methods, but at full foliage, retention was 25 and 63 %, respectively. On both types of tree the proportions of the spray deposited on the tree components were related to the surface areas of those components.     

Oxidative degradation of chlortoluron,propiconazole, and metalaxyl in suspension cultures of various crop plants

The metabolism of chlortoluron, (N′-(3-chloro-4-methylphenyl)-N,N-dimethylurea), propiconazole (1-[2-(2′,4′-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl-methyl]-1H-1,2,4-triazole), and metalaxyl (dl-N-(2,6-dimethylphenyl)-N-(2′-methoxyacetyl) alanine methyl ester) was investigated in suspension cultures of crop species for which differences in metabolism had been demonstrated at the intact plant level. Uptake and metabolism of chlortoluron by cultures of Italian rye-grass (Lolium multiflorum) was slow, the metabolites detected (42% of applied radioactivity after 13 days) being products of ring methyl oxidation and N-monodealkylation reactions. In sharp contrast, metabolism in a cotton (Gossypium hirsutum) suspension culture was extremely fast (72% after 4 hr) and was attributed to extensive N-didealkylation in addition to rapid ring methyl oxidation. This rate of metabolism also implied a very rapid uptake of chlortoluron by the cotton culture. ¹⁴C-labelled propiconazole became rapidly associated with cells of wheat (Triticum aestivum) and rice (Oryza sativa) following treatment of suspension cultures. Uptake was initially more rapid in the rice culture (36% of applied radioactivity after 8 h compared to 19% for wheat) which, together with a slower rate of metabolism, resulted in more unchanged propiconazole being associated with rice cells. On a parts-per-million basis these results indicated an apparent 10-fold accumulation of propiconazole in rice cells compared to 5-fold in the wheat culture. Propiconazole metabolite patterns were similar in cultures of both species and indicated side-chain hydroxylation as the principal pathway. Uptake of metalaxyl was slow in suspension cultures of both lettuce and potato (≅ 20% after 17 days). Subsequent metabolism was also slow but appeared to be limited by the poor rate of uptake. Both cultures were found to be similarly versatile with respect to metabolic attack on metalaxyl, which included ring methyl hydroxylation, aryl hydroxylation, ester cleavage, ether cleavage (O-dealkylation), and N-dealkylation (side-chain cleavage), the hydroxylation reactions being quatitatively the more important. The results for all three pesticides are compared to those obtained previously from studies with intact plants of the same species.     

Increased activity and reduced sensitivity of glutamine synthetase in glufosinate‐resistant vetiver (Vetiveria zizanioides Nash) cells

Vetiver (Vetiveria zizanioides Nash) cells derived from an inflorescence were cultured in a modified N6 liquid medium supplemented with 10 µm 2,4‐D and 10 mm proline. Exponentially growing cell suspensions were subcultured with a selection medium containing glufosinate (ammonium dl ‐homoalanin‐4‐yl(methyl)phosphinate). The glufosinate‐resistant cells which can grow in a medium containing 5 × 10^?5 M glufosinate was selected by a stepwise selection, and its I₅₀ value was determined to be 4.2 × 10^?5 M. The growth of susceptible cells was inhibited by lower concentrations of glufosinate and its I₅₀ value was 2.5 × 10^?7 M. This indicated that the selected cells were 170‐fold resistant compared with the susceptible cells. Glutamine synthetase (GS) activity of the resistant cells was twice as high as that of the susceptible cells. The I₅₀ values of glufosinate were 3.2 × 10^?5 M and 9.0 × 10^?7 M for GS from the resistant and susceptible cells, respectively. The accumulation of ammonia caused by GS inhibition was higher in the susceptible cells. Absorption of [3,4–¹⁴C]glufosinate was not significantly different between the resistant and susceptible cells. Both cell types did not metabolize glufosinate. These results suggest that the resistance of the selected vetiver cell suspension to glufosinate is mainly due to increased GS activity and its decreased sensitivity to the herbicide.     

Titres of precocene ii (6, 7-dimethoxy-2, 2- dimethylchromene) and its metabolites in the haemolymph of larvae of the african armyworm Spodoptera exempta (walker) following topical treatment with the compound

No precocious metamorphosis or other morphogenetic effects were seen following topical treatment of fifth instar Spodoptera exempta with pre- cocene II. [3H]-Precocene II penetrated the larvae rapidly following topical application. An uptake of 47% was recorded in the first hour and an average of 27% for the first 3 h. Radioactivity in the haemolymph reached a maximum 4 h after treatment at 6–8% of the applied dose. A maximum titre of precocene of 1.1 × 10^?4 _M was observed 2 h after treatment and a biological half-life of around 1 h was recorded for the first 6 h. The metabolite precocene 11–3, 4-dihydrodiol appeared in the haemolymph with a maximum titre of 1.1 × 10^?4 _M at 4 h suggesting metabolism via the 3, 4-epoxide. At the same time an unidentified metabolite was observed possibly corresponding to the 6- and 7-(O)-desmethylated products described by others. Very large quantities of highly polar materials were observed in the haemolymph throughout the experiment and it is thought that these corresponded to conjugates. The evidence suggests that peripheral detoxication mechanisms do not operate sufficiently rapidly to prevent the establishment of a high titre of precocene. This, however, did not affect the corpora allata in this insect, whereas in a sensitive species that has been studied by other workers, necrosis of the glands would have resulted. Alternative explanations for insensitivity are discussed.     

Degradation of ioxynil to CO2 in soil

Degradation of ioxynil (4-hydroxy-3,5-diiodobenzonitrile) to CO₂ was detected in a clay loam, high organic matter content soil. The majority of radioactivity was recovered as ¹⁴CO₂ from both ring-labeled and cyano-labeled ioxynil; however, ¹⁴CO₂ was always released from cyano-labeled ioxynil at a much faster initial rate. No ¹⁴CO₂ was released in treated sterile soil, either aerobically or anaerobically. Production of ¹⁴CO₂ from cyanolabeled and ring-labeled ioxynil was greatly inhibited by HgCl₂ (10^?5M), and p-chloromercuribenzoate (5 × 10^?5M), but slightly inhibited by ferricyanide (10^?4M). No ¹⁴CO₂ was evolved from ring-labeled ioxynil under anaerobic conditions. These observations indicated that the degradation of ioxynil to CO₂ in soil was a microbial action and was oxygen dependent. This is consistent with the known mechanism of oxygenases in degrading benzene rings. Anaerobically, a small amount of ¹⁴CO₂ was released from cyano-labeled ioxynil. Thin-layer chromatographic analyses of the culture supernatant revealed that 3,5-diiodo-4-hydroxybenzamide and 3,5-diiodo-4-hydroxybenzoic acid were intermediate metabolites.     

Metabolism of cisanilide (cis-2,5-dimethyl-1-pyrrolidinecarboxanilide) by excised leaves and cell suspension cultures of carrot and cotton

Major methanol-soluble metabolites of cisanilide (cis-2,5-dimethyl-1-pyrrolidinecarboxanilide) were isolated from excised, pulse-treated carrot and cotton leaves. They were identified as O-glucoside conjugates of primary aryl and alkyl oxidation products, 2,5-dimethyl-1-pyrrolidine-4-hydroxycarboxanilide and 2,5-dimethyl-3-hydroxy-1-pyrrolidinecarboxanilide. Comparative studies with carrot and cotton cell cultures showed similar initial pathways of cisanilide metabolism. Time-course studies with [¹⁴C-pyrrolidine]- and [¹⁴C-phenyl]cisanilide showed little, if any, cleavage of the herbicide molecule in either excised leaves or cell cultures. Quantitative differences in the metabolism of cisanilide by cell cultures and excised leaves included; a reduced capacity of cell cultures to form secondary glycoside conjugates and an increased ability of cell cultures to form methanol-insoluble residues.     

Effect of 2,4,5-T and picloram on the regeneration of blackberry (Rubus procerus P.J. Muell) from root segments

The formation of roots and shoots on root segments of Rubus procerus P.J. Muell was prevented by soaking the segments for 24 h in a 10^?4M solution of 2,4,5-T or a 10^?5M solution of picloram. Shoot numbers were significantly increased after treatment with 10^?9M and 10^?10M 2,4,5-T, but picloram did not cause a significant increase in shoot numbers. Measurement of the concentration of 2,4,5-T in the extracambial tissue showed that roots treated with 10^?4M 2,4,5-T contained 5× 10^?8 mmole 2,4,5-T per mg dry weight, and by extrapolation, roots treated with 10^?9M 2,4,5-T contained 2× 10^?10 mmole/mg dry weight. Action du 2,4,5-T et du piclorame sur la régénération de la ronce (Rubus procerus P.J. Muell) è partir de fragments de racines La formation de racines et de tiges è partir de fragments de racines dc Ruhus procerus P.J. Muell a été supprimée par trempage des fragmenls pendant 24 heures dans une solution a 10^?4M et de 2.4,5-T, ou dans une solution 10^?5M de piclorame. Le nombre de pousses s'est accru significativement après traitement avec le 2,4,5.-T è 10^?9M et 10^?10M, mais le piclorame n'a pas provoqué d'accroissemcnt significatif du nombre de pousses. La mesure de la concentration de 2,4,5-T dans le tissu extra-cambial a montré que les racines trailées avec du 2,4,5-T è 10^?4M contenaient 5×10^?8 mmole de 2.4,5-T par mg de poids sec et par extrapolation, quc les racines traitées avec du 2,4,5-T k 10^?9M devaient contenir 2 × 10^?12 mmole/mg de poids sec. Die Wirkiing von 2,4,5-T und Picloram auf den Wuchs der Wurzehegmenten von Bromheeren (Rubus procerus P.J. Muell). Die Bildung von Wurzeln und Sprossen aus Wurzelsegmen-ten von Ruhu.i procerus P.J. Muell wurde durch 24-stündiges Einlegen der Wurzelstücke in 10^?4M 2,4,5-T bzw 10^?5M Picloram verhindert. Die Anzahl neugebiideter Sprosse wurde nach Einlegen in 10^?9M und 10^?10M 2,4,5-T, nicht jedoch durch Picloram, signifikant erhöht. Im extracambialen Gewebe von Wurzeln, die mit 10^?4M 2,4,5-T behand-elt worden waren, wurden 5×10^?8mMol 2,4,5-T je mg Trockengewiclu bestimmt. Durch Extrapolation wurde ermittclt. dass mit 10^?9M 2,4,5-T behandelte Wurzeln 2× 10^?12mMol/mg Trockengewicht cnthielten.     

Disposition and metabolism of [14C]chlorpyrifos in the black imported fire ant, Solenopsis richteri Forel

The short-term disposition and metabolism of topically administered [¹⁴C]chlorpyrifos was assessed in the black imported fire ant (Solenopsis richteri Forel) in the presence and absence of the mixed-function oxidase inhibitor piperonyl butoxide. Chlorpyrifos is readily absorbed into an internal organosoluble fraction which was quickly converted into a water-soluble fraction. The radioactivity was slowly excreted over a 24-hr period. Piperonyl butoxide slowed the conversion of the internal organosoluble radioactivity to the water-soluble fraction. Thin-layer chromatography indicated that piperonyl butoxide slowed the conversion of chlorpyrifos to material remaining at the origin, presumably water-soluble metabolites. The results of acid hydrolysis studies indicated that the water-soluble radioactivity was comprised mainly of conjugates. Although very little chlorpyrifos oxon was recovered in the metabolism experiments, in vitro studies on fire and head homogenates showed the compound to be an extremely potent anticholinesterase, with an I₅₀ of 4.6 × 10^?10M, while a major metabolite, 3,5,6-trichloropyridinol, was an ineffective acetylcholinesterase inhibitor.     

Fungicidal activity and chemical constitution. Part XXI: The activity of substituted 1, 4-naphthoquinones and quinoline-5, 8-diones against apple powdery mildew

Several series of alkyl-substituted amino-, bromo-, chloro-, fluoro- and hydroxy-1, 4-naphthoquinones, as well as some 6-alkylaminoquinoline-5, 8-diones and 7-alkyl-6-hydroxyquinoline-5, 8-diones were prepared and tested as protectant fungicides against apple powdery mildew (caused by Podosphaera leucotricha). While most of the compounds did not reduce infection when applied at 10^?3M, several 3-alkyl-2-bromo-and 3-alkyl-2-chloro-1, naphthoquinones were found to have ED₅₀ values below 50 × 10^?5M.     

枯草芽孢杆菌BS80-6对苹果采后炭疽病的控病效果及作用机制

为提高枯草芽孢杆菌的生防效果,通过离子束诱变筛选出BS80-6菌株.利用生物测定方法研究BS80-6菌株及不同处理方法在不同贮藏温度下对采后苹果炭疽病的控制效果和作用机制.结果表明,BS80-6能显著提高对苹果炭疽菌的抑制作用.枯草芽孢杆菌BS80-6对苹果果实炭疽病的防治效果以活菌液效果最好,菌丝生长抑制率为80.14%,孢子萌发抑制率为98.65%,控病效果为60.34%;灭菌液和过滤液对苹果炭疽菌也有一定的抑制效果.贮藏温度明显影响BS80-6对苹果炭疽病的防治效果;接种方式对控病效果影响显著,先接拮抗菌再接病菌的防效好于先接病菌再接拮抗菌.