The control of Holcus lanatus in perennial ryegrass swards by asulam.

Asulam was evaluated in three fields experiments for the control of Yorkshire fog (Holcus lanatus L.) in perennial rygrass(Lolium perenneL). It was used in 1976 on a 3 year-old ryegrass/timothy (Phleum pratense L.) sward in comparison with propyzamidc, in 1977 on a 9 year-old ryegrass pasture grazed at two stocking rates and in 1978 on an intensively managed ryegrass dominant sward. Asulam at 1.75 kg ha^?1 gave good selective control in all the field experiments and was more effective under higher than lower slocking rates. In laxly grazed swards it was most effective when sprayed in October. Propyzamide also controlled H. lanatus and increased yields of while clover (Trifolium repens L.) even at 0.25 kg ha^?1 but it damaged the sown grasses and increased the growth of broad-leaved weeds.     

The selective control of Poa trivialis by dalapon in perennial ryegrass crops grown for seed

The effects of dalapon applied in March and April at doses between 1·7 and 2·8 kg/ha a.e. on Poa trivialis present in crops of perennial ryegrass grown for seed, were investigated. Good control of P. trivialis was achieved at all doses sprayed at both times. Reductions in numbers of inflorescences and yield of seed of perennial ryegrass were however recorded, particularly after applications in March. Differences in the response of perennial ryegrass cultivars were also observed; cultivar S.23 was more susceptible to the herbicide than cultivar S.24. The results also suggest that the variation in response of cultivar S.24 in different experiments within the study may be due to the influence of climatic factors. Lutte sélective contre Poa trivialis avec le dalapon dans des cultures porte-graines de ray-grass vivace. Les effets du dalapon, appliqué en mars et en avril à des doses comprises entre 1,7 et 2,8 kg/ha (é.a.) sur Poa trivialis présent dans des cultures porte-graines de ray-grass vivace, ont étéétudiés. Une bonne efficacité sur Poa trivialis a été obtenue à toutes les doses appliquées aux deux époques. Toute fois, des réductions du nombre des inflorescences et des rendements en graines du ray-grass vivace, ont été constatés, particuliérement aprés les applications faites en mars. Des différences entre les réactions des cultivars ont été aussi observées: le cultivar S.23 s'est révélé plus sensible que le cultivar S.24. Les résultats suggèrent que les réactions différentes du cultivar S.24 dans diverses expériences comprises dans ce travail, peuvent également êre dues à l'influence de facteurs climatiques. Selektive Bekämpfung durch Dalapon von Poa trivialis in Deutschem Weidelgras für Samenproduktion Die Wirkung von Dalapon gegen Poa trivialis in Kulturen zur Samengewinnung von Deutschem Weidelgras wurde untersucht. Im März und April wurden Dosierungen zwischen 1,7 und 2,8 kg/ha appliziert. Poa trivialis konnte in alien Dosierungen und an beiden Behandlungszeitpunkten bekämpft werden. Minderungen in der Zahl der Blutenstände und Grassamenerträge von Deutschem Weidelgras wurden jedoeh festgestellt, insbesondere nach Applikation im März. Ebenfalls reagierten die Weidelgrassorten untersehiedlich. Sorte S.23 war gegen das Herbizid empfindlicher als Sorte S.24. Die Resultate deuten auch an, dass die unterschiedliche Reaktion von Sorte S.24 in den Experimenten dieser Untersuchung auf den Einfluss von Klimafaktoren zurückgeführt werden könnte.     

The effects of herbicide and fungicide treatments on the growth and provitamin a content of lettuce

Plots of lettuce were grown in the field in soil treated with the herbicides propyzamide and chlorpropham, either separately, or as a mixture, or with one of the fungicides iprodione, vinclozolin or benomyl. Four harvests were made and at each, the mean fresh weight per lettuce treated with the mixture propyzamide plus chlorpropham, or with iprodione, was greater than that of the control. Propyzamide, chlorpropham or benomyl reduced lettuce fresh weight compared with the untreated controls, but vinclozolin had no effect. The concentration of total carotene in the lettuce was increased by treatment with propyzamide, chlorpropham, propyzamide plus chlorpropham, or iprodione. Treatment with vinclozolin or benomyl had no effect.     

大麦种传病害重发原因及防治对策

由于气候变化、品种感病、种子未经处理等原因，近年来大麦种传病害持续上升，其防治对策有精选种子、筛选抗病品种、浸种、拌种等措施。     

Action of the fungicide tridemorph on the glucose,lactate and succinate dehydrogenase activities of some tridemorph-sensitive and -resistant bacteria

The systemic morpholine fungicide tridemorph, which is known to exert its antifungal action through inhibition of ergosterol biosynthesis, can also inhibit the growth of organisms which are incapable of sterol biosynthesis. It was found to inhibit strongly glucose and lactate dehydrogenase activities in cultures of four Gram( +) bacteria, Rhodococcus sp. AK 1, Bacillus cereus Frankland & Frankland, Bacillus subtilis (Ehrenberg) Cohn, Nocardia asteroides and a Gram(?) bacterium, Rhizobium leguminosarum. Growth of these bacteria was inhibited by tridemorph at concentrations between 7 and 60 mg litre^?1. In contrast, similar dehydrogenase activities in other Gram(?) organisms, Escherichia coli Cast. & Chalm. and Azotobacter vinelandii, which showed no growth inhibition at 200 mg litre ^?1 tridemorph, were either not inhibited or inhibited only slightly. Similarly, succinate dehydrogenase activity in Rhodococcus sp. AK 1 was more strongly inhibited by tridemorph than that in E. coli. In cell-free extracts of Rhodococcus sp. AK1 and E. coli, lactate dehydrogenase activity was also inhibited by tridemorph to a much greater extent in the sensitive strain (63%) than in the resistant ones (8%).     

Difenzoquat, 1,2-dimethyl-3,5-diphenylpyrazolium ion,a selective herbicide for the control of wild oats (Avena spp.) in wheat and barley

The results of a series of replicated trials and of a series of commercial grower trials conducted in the United Kingdom during 1972 and 1973, established the effectiveness of difenzoquat (1,2-dimethyl-3,5-diphenylpyrazolium ion) as the methyl sulphate as a selective post-emergence herbicide for the control of wild oats in wheat and barley. Doses of 0.75 to 1.0 kg cation/ha applied at 200 or 400 litre/ha and at 2.1 or 3.5 kg/cm² gave good to excellent results when applied at crop growth stages 3 to 5 (Feekes—Large scale) for spring crops and at crop growth stages 4 to 6 for winter crops. In these experiments wild oats over a range of stages from 1st leaf to tillering were well controlled.     

The plasma membrane as a barrier to herbicide penetration and site for adjuvant action

Adjuvants are traditionally thought to exert their main effect on the cuticle or spray droplet to enhance foliar-applied herbicide penetration. However, considerable evidence exists indicating that the plasma membrane is a barrier to intracellular penetration of herbicides and a site of action for adjuvants. Surfactants may penetrate through the cuticle and into the region of the plasma membrane. Insertion into the membrane causes a general “ loosening” to provide greater penetration by highly polar herbicides such as glyphosate. Weak acid herbicides typically have a lipophilic moiety and, therefore, can move more easily through the membrane but the rate and accumulation is dependent on pH conditions across the membrane. Ammonium salts have been shown to affect the pH of the apoplast in a manner which allows faster penetration and greater accumulation of weak acid herbicides. Examination and understanding of the plasma membrane as a barrier to herbicide penetration will aid in defining the mechanisms of adjuvant action and improve the efficiency of agrochemical use.     

Chlorophyll fluorescence as a marker for herbicide mechanisms of action

Photosynthesis is the single most important source of O₂ and organic chemical energy necessary to support all non-autotrophic life forms. Plants compartmentalize this elaborate biochemical process within chloroplasts in order to safely harness the power of solar energy and convert it into usable chemical units. Stresses (biotic or abiotic) that challenge the integrity of the plant cell are likely to affect photosynthesis and alter chlorophyll fluorescence. A simple three-step assay was developed to test selected herbicides representative of the known herbicide mechanisms of action and a number of natural phytotoxins to determine their effect on photosynthesis as measured by chlorophyll fluorescence. The most active compounds were those interacting directly with photosynthesis (inhibitors of photosystem I and II), those inhibiting carotenoid synthesis, and those with mechanisms of action generating reactive oxygen species and lipid peroxidation (uncouplers and inhibitors of protoporphyrinogen oxidase). Other active compounds targeted lipids (very-long-chain fatty acid synthase and removal of cuticular waxes). Therefore, induced chlorophyll fluorescence is a good biomarker to help identify certain herbicide modes of action and their dependence on light for bioactivity.     

Field evaluation of a decision support system for herbicidal control of Avena sterilis ssp. ludoviciana in winter wheat

Two field studies were conducted in Central and Northern Spain over a total of five seasons to assess the usefulness of a decision support system (AVENA-PC) from agronomic, economic and environmental points of view on herbicidal control of Avena sterilis ssp. ludoviciana in winter wheat. The control treatments evaluated were: (i) AVENA-PC-based recommendations, (ii) full herbicide dose (standard farmer practice), (iii) half herbicide dose and (iv) no herbicide. The herbicide rates used in the AVENA-PC treatment averaged 65% and 30% lower than the full and half dose treatments respectively. AVENA-PC implementation controlled A. ludoviciana with similar efficacy as standard herbicide treatments. Nevertheless, it did support a reduction in relation to the non-herbicide treatment. Yields obtained with AVENA-PC were, in general, not statistically different to those obtained with herbicide treatments and were on average 69% higher than those in the no herbicide application strategy. Comparing AVENA-PC economic performance with the other treatments there were, in general, no significant statistical differences in Central Spain. In Northern Spain, all herbicide treatments had similar net returns, with there being no statistical differences between AVENA-PC and the herbicide treatments. However, there were differences recorded with the non-herbicide treatment. The results of this research indicate that AVENA-PC, due to its flexibility, may recommend less herbicide than the standard farmer practice, providing clear environmental benefits and adequate weed control with maintained crop yield and net returns similar to standard farmer practice.     

On a difference in the antifungal activity of tridemorph and its formulated product Calixin

The antifungal effects of tridemorph and its formulated product Calixin were compared in vitro on Ustilago maydis, Saccharomyces cerevisiae, Torulopsis candida, Botrytis allii, and Cladosporium cucumerinum. MIC values for both products were about the same. In liquid media the products were somewhat more effective than on solid media. T. candida proved sensitive only at pH 5, but the other organisms were as sensitive at pH 7 as at pH 5. Whereas tridemorph even at high concentrations did not affect oxygen consumption of these organisms, Calixin at concentrations slightly above the MIC values appeared to inhibit respiration. This effect of Calixin could be explained by the presence of Nekanil LN in the formulation. This compound inhibited both growth and respiration of the organisms at high concentrations; however, in the simultaneous presence of tridemorph a synergistic effect on oxygen consumption was observed.     

Difolatan,a promising fungicide for control of the tapping panel disease Black Thread in Hevea brasiliensis

In field experiments for control of Black Thread, caused byPhytophthora palmivora, the mean damage done to the trees in the previous rainy season should be of the same level for all the treatments. Satisfactory results and better disease control were obtained with Difolatan in weekly applications when compared with some recommended fungicides for tapping panel diseases. No unfavorable side effects were observed on the latex crop or to the trees. Difolatan (active ingredient: N-(1,1,2,2-tetrachloroethylsulfenyl)-cis4-cyclohexene-1,2-dicarboximide) is known to be of low mammalian toxicity.Samenvatting In veldproeven ter bestrijding van de tapvlakziekte Streepjeskanker, veroorzaakt doorPhytophthora palmivora, dient de gemiddelde schade—aangericht in het voorafgaande regenseizoen—in alle behandelingen van hetzelfde niveau te zijn. Op deze wijze worden de infectie-kansen gelijkelijk verdeeld over de behandelingen, aangezien de oude schade bepalend is voor de mate van infectie. Een betere ziekte-bestrijding werd verkregen met het fungicide Difolatan dan met enkele bekende middelen ter bestrijding van tapvlakziekten. Bevredigende resultaten werden verkregen bij wekelijkse toediening. Behandelingen met Difolatan hebben waarschijnlijk geen onaanvaardbare nevenwerking op de bomen en de latex; het middel is weinig giftig.     

猕猴桃软腐病病原菌的分离鉴定及其防治药剂筛选

为明确引起猕猴桃软腐病病原菌的种类并筛选有效防治药剂,2015年10月于安徽省金寨县猕猴桃基地采集具有典型软腐病症状的40个果实病样,对分离所得病原菌进行致病性测定、形态学和分子生物学鉴定,同时测定了10种常用药剂对病原菌的抑菌效果。结果显示,结合分离物的形态学特征及rDNA-ITS、β-tubulin和EF-1α基因序列分析结果,确定10株经致病性验证的菌株均为葡萄座腔菌Botryosphaeria dothidea。药剂筛选结果显示,多菌灵对该病原菌菌丝生长抑制效果最好,抑制率高达91.97%,其次是95%三唑醇1 600倍液,抑制率为81.72%,其余药剂对菌丝生长的抑制率均低于80.00%;多粘芽胞杆菌对该病原菌孢子萌发抑制效果最好,未见该病菌孢子萌发,70%代森锰锌可湿性粉剂1 000倍液、12.5%烯唑醇可湿性粉剂3 000倍夜、10%混合脂肪酸水剂100倍液、95%三唑醇原药1 600倍液和1.8%辛菌胺醋酸盐水剂180倍液对病原菌孢子萌发的抑制率均大于81.00%。表明多菌灵和多粘芽胞杆菌是防治葡萄座腔菌菌丝生长和孢子萌发的最佳药剂。     

Decay control and fungicide residues in citrus fruits seal-packed in a high-density polyethylene film

The effects of a new packaging method of sealing individual fruits in film of highdensity polyethylene (HDPE), on decay control and the residue levels of various fungicides applied to the fruit, were investigated with four different citrus cultivars. HDPE seal-packaging by itself reduced the decay of Marsh grapefruit but slightly enhanced the decay of Valencia orange fruit in comparison with conventionally handled fruit. Seal-packaging of individual fruit resulted in much less decay than sealing a whole carton of fruit together. The fungicides imazalil, sec-butylamine, 2-phenylphenol, benomyl and thiabendazole markedly reduced the decay of sealed fruit in all cultivars of citrus fruits tested. Residue levels in treated fruit were below the tolerances permitted. The new method of packaging had no effect on the residue levels of benomyl, 2-phenyl-phenol and thiabendazole in the fruit; neither did it affect the extent of absorption of these fungicides into the fruit. Only the volatile fungicide sec-butylamine was found at a higher level (73% higher in the packaged fruit compared with conventionally treated fruit).     

Mode of action of naphthalic anhydride as a safener for the herbicide AC 263222 in maize

In hydroponic experiments, seed-dressing with the herbicide safener 1,8-naphthalic anhydride (NA), significantly enhanced the tolerance of maize, (Zea mays L., cv. Monarque) to the imidazolinone herbicide, AC 263222, (2-[4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]-5-methylnicotinic acid). Uptake, distribution and metabolism studies where [¹⁴C]AC 263222 was applied through the roots of hydroponically grown maize plants showed that NA treatment reduced the translocation of radiolabel from root to shoot tissue and accelerated the degradation of this herbicide to a hydroxylated metabolite. Reductions in the lipophilicity and, therefore, mobility of this compound following hydroxylation may account for NA-induced retention of radiolabel in the root system. Hydroxylation of AC 263222 suggested that NA may stimulate the activity of enzymes involved in oxidative herbicide metabolism, such as the cytochrome P₄₅₀ mono-oxygenases. In agreement with this theory, the cytochrome P₄₅₀ inhibitor, 1-aminobenzotriazole (ABT), synergized AC 263222 activity and inhibited its hyroxylation in vivo. NA seed-dressing enhanced the total cytochrome P₄₅₀ and b₅ content of microsomes prepared from etiolated maize shoots. Isolated microsomes catalyzed AC 263222 hydroxylation in vitro. This activity possessed the characteristics of a cytochrome P₄₅₀ mono-oxygenase, being NADPH-dependent and susceptible to inhibition by ABT. Activity was stimulated four-fold following NA seed treatment. Differential NA enhancement of AC 263222 hydroxylase and the cytochrome P₄₅₀-dependent cinnamic acid-4-hydroxylase (CA4H) activity, suggested that separate P₄₅₀ isozymes were responsible for each activity. These results indicate that the protective effects of NA result from enhancement of AC 263222 hydroxylation and concomitant reduction in herbicide translocation. This may be attributed to the stimulation of a microsomal cytochrome P₄₅₀ system. © 1998 SCI.     

Plant cell membrane as a marker for light-dependent and light-independent herbicide mechanisms of action

Plant cells possess a number of membrane bound organelles that play important roles in compartmentalizing a large number of biochemical pathways and physiological functions that have potentially harmful intermediates or by-products. The plasma membrane is particularly important as it holds the entire cellular structure whole and is at the interface between the cell and its environment. Consequently, breaches in the integrity of the lipid bilayer, often via reactive oxygen species (ROS)-induced stress membrane peroxidation, result in uncontrolled electrolyte leakage and in cell death. A simple 3-step bioassay was developed to identify compounds that cause electrolyte leakage and to differentiate light-dependent mechanisms of action from those that work in darkness. Herbicides representative of all known modes of action (as well as several natural phytotoxins) were selected to survey their effects on membrane integrity of cucumber cotyledon discs. The most active compounds were those that are known to generate ROS such as the electron diverters and uncouplers (paraquat and dinoterb) and those that either were photodynamic (cercosporin) or caused the accumulation of photodynamic products (acifluorfen-methyl and sulfentrazone). Other active compounds targeted lipids (diclofop-methyl, triclosan and pelargonic acid) or formed pores in the plasma membrane (syringomycin). Herbicides that inhibit amino acid, protein, nucleotide, cell wall or microtubule synthesis did not have any effect. Therefore, it was concluded that the plant plasma membrane is a good biomarker to help identify certain herbicide modes of action and their dependence on light for bioactivity.     

Plumbagin as a new natural herbicide candidate for Sicyon angulatus control agent with the target 8-amino-7-oxononanoate synthase

A natural compound plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) was isolated from the leaves of Plumbago auriculata and found to inhibit the enzyme, 8-amino-7-oxononanoate synthase (AONS, also known as 7-keto-8-aminopelargonate synthase, KAPAS) an IC₅₀ of 2.1 μM in vitro. Biotin supplement significantly rescued the plant injury caused by the plumbagin treatment, and this result confirmed the target site, AONS. Foliar application of 1000 ∼ 2000 μg/mL plumbagin in a greenhouse condition showed lethal activity against eight species of weeds, containing three grass species of Sorghum bicolor, Echinochloa crus-galli, Digitaria sanguinalis and five broad leaf species of Solanum nigrum, Aeschynomene indica, Abutilon avicennae, Xanthium strumarium, Calystegia japonica. Field trial of foliar application with plumbagin 2000 μg/mL have successfully controlled 10 ∼ 15 leaf-stages and 2 ∼ 3 m vine lengths of Sicyos angulatus at the natural habitats around riparian zone in the Nam-Han River in Korea. Visual symptom of desiccation might be induced by the physiological cellular leakage which was significantly dose dependent on the plumbagin treatment regardless of light.     

防治苹果树腐烂病杀菌剂的室内筛选

 The inhibitory effects of 10 fungicides on apple tree valsa canker were compared on dishes and twigs. The results showed that conidia germination and mycelial growth were inhibited by all fungicedes tested. The EC₅₀ value of Difenoconazole was 6. 1×10^-3μg·mL^-1, the lowest among tested fungicide in inhibiting conidia germination. Tebuconazole and Imazalil also showed obvious inhibition effect. Thiophanatemethyl was the least efficient with the EC₅₀ value 2.6×10¹ μg·mL^-1. Difenoconazole also showed the highest activity for inhibiting mycelial growth with ECho value of 2.3×10^-2 μg·mL^-1. Tebuconazole was better than other fungicide. Thiophanate-methyl and Propineb were the least efficient with quite high EC₅₀ value. Furthermore, the size of the lesion after inoculation on excised twigs also revealed that Difenoconazole was most efficient because it showed the smallest lesion of 394 mm² compared with other tested fungicides. So Difenoconazole and Tebuconazole could be used to control apple tree valsa canker in field to subsititute forbided fungicides such as asomate.