Retention and distribution of dry powder and liquid formulations of insecticides and fungicides on commercially dressed cereal seed

Analysis of samples of seeds, mostly wheat, treated commercially with insecticides and fungicides showed that many carried much less than the theoretical dose, some less than one-tenth. The average loadings of seeds treated with dry powder formulations were nearly always small, but the distribution of insecticide between seeds was fairly uniform. The average loading of seeds treated with liquid formulations was closer to the target, but the distribution was irregular, most of the seeds carrying little insecticide and a few seeds amounts large enough to be phytotoxic. Insecticides applied as dry powders do not adhere strongly to the seeds, but they remain in association with seeds contained and carried in bags. Applied as liquids, insecticides are difficult to remove from seeds. The ratio of insecticide to fungicide on seeds dressed with powders containing both usually resembled the ratio in the original powder. With liquid seed dressings of insecticide and fungicide applied separately in different formulations, the ratio of insecticide to fungicide often differed widely from the theoretical. The average loading of fungicide was close to the target, but the average amount of insecticide was often much less. With either wet or dry dressings, the amount of pesticide on seeds was consistently greater from some merchants than from others. This was independent of the machinery used. Loadings were not consistently affected by type of seed-dressing machinery or formulation, stage of operation, weather or variety of seed.     

Incorporation and stability of chlorfenvinphos,chlorpyrifos, diazinon and phorate in peat blocks

Factors likely to influence the uniformity of treatment and the stability of the insecticides incorporated into peat blocks were investigated. When an Adelphi horizontal mixer was used, 90% of the blocks contained the mean dose (±10%) after dry-mixing the diazinon granules for 3 min. Treatment was slightly less uniform using a concrete mixer or a spade. Between-block variability was greatest when diazinon was applied to the wet surfaces of prepared blocks; in this process, sprinkling granules by hand was less erratic than spraying a liquid formulation. When granular, wettable powder, or emulsifiable concentrate formulations of diazinon were incorporated using the Adelphi mixer, neither the between-block variability nor the subsequent stability of the insecticide were significantly influenced by the formulation used. Insecticide stability was studied by incorporating chlorfenvinphos, chlorpyrifos, diazinon and phorate at 10 mg a.i. per block in January, March, May and July. The relative order of persistence was chlorfenvinphosChlorpyrifos > phorate≫diazinon. There was little loss of insecticide ( < 10%) from the blocks treated with chlorfenvinphos or chlorpyrifos, and the stability of the insecticides was unaffected by seasonal temperature changes, but the rate of loss of diazinon increased markedly from January to July. The rate of oxidation of phorate to its sulphoxide and sulphone analogues increased gradually from January to May but was much slower than in the field after a bow-wave application. With all insecticides, there was no significant difference in loss rates at 25 and 10 mg a.i. per block. After incorporation into three moss peats and two proprietary blocking composts, there was no consistent difference in the rates of loss of either diazinon or of total phorate residues, although the rates of oxidation of phorate and its sulphoxide were not similar in all the peats and composts. It was concluded that, despite the substantial water content and high insecticide concentrations, the principal factor determining insecticide behaviour in the blocks was the adsorptive capacity of the peat.     

Influence of block and cell size,growing medium and insecticide dose on the behaviour and uptake of phorate by lettuce and uptake of carbofuran and chlorfenvinphos by calabrese

Phorate residues in peat blocks and lettuce were determined following incorporation of the insecticide into different block and ‘Speedling’ cell sizes. Between-block variability was influenced little by block size. Phorate oxidation was most extensive in the largest blocks containing the smallest dose. Total residue concentrations in the lettuce declined from the time of planting to harvest, although accumulation of insecticide continued and was related more to dose than to block or cell size. Residues in the lettuce at harvest exceeded the proposed maximum limit of 0.2 mg kg^?1 in some treatments. Residues at planting comprised mainly the parent sulphoxide and sulphone, but by harvest, the oxygen analogue sulphoxide and sulphone predominated. Lettuce weight was not influenced by dose but was related directly to block size. Carbofuran and chlorfenvinphos residues were determined in calabrese sown into two sizes of blocks. At planting time, carbofuran residue concentrations were 100 times greater than those of chlorfenvinphos but residues of both insecticides in the mature heads were < 0.01 mg kg^?1. Seedling weights in both sowings declined with increasing concentrations of the insecticides. It was concluded that manipulations of block size and the dose of insecticide need to be evaluated for individual insecticide/crop combinations to exploit the technique fully.     

杀菌剂、除草剂和杀虫剂的先导筛选规则

为了寻找适合于农药的先导筛选规则,对242个杀菌剂、512个除草剂和399个杀虫剂的5个描述符: 疏水常数(LogP)、相对分子质量(MW)、氢键给体数(NHD)、氢键受体数(NHA)、分子极性表面积(PSA)和毒性进行了计算和分析,提出了杀菌剂、除草剂和杀虫剂先导化合物的筛选规则。测试结果显示:杀菌剂、除草剂和杀虫剂的先导筛选规则总体正确率分别为73.3%、 53.3%和63.3%。     

Field relevance of a synergistic effect observed in the laboratory between an EBI fungicide and a chloronicotinyl insecticide in the honeybee (Apis mellifera L,Hymenoptera)

It had been found earlier that the chloronicotinyl insecticide thiacloprid (as the 480 g litre(-1) SC Calypso) poses a favourably low toxicity hazard to the honeybee, Apis mellifera L. As with pyrethroids, the metabolization of chloronicotinyl compounds involves monooxygenases, which are known to be inhibited by some ergosterol biosynthesis inhibitor (EBI) fungicides potentially co-applied with these insecticides. The potential synergistic enhancement of the toxicity of thiacloprid to honeybees when co-applied with such fungicides was therefore studied under laboratory and semi-field conditions. Fungicides of other chemical classes were also examined for synergistic potential to reveal other metabolic interactions. In the laboratory, only a slight synergistic effect was observed with the anilinopyrimidine fungicide examined, while a significant enhancement of thiacloprid toxicity to honeybees was found with EBI fungicides. In three tunnel tests conducted under different environmental conditions to simulate field exposure, no increased mortality was observed when honeybees were directly sprayed with thiacloprid (Calypso) alone or in combination with the EBI fungicide tebuconazole (250 g litre(-1) EW, Folicur). There was also no synergized reduction in the foraging intensity on the treated crop. In general, the foraging intensity decreased after thiacloprid treatment but was restored within 24-48 h. The hive vitality was not affected by either thiacloprid or its tank mix with tebuconazole. Our results suggest that, at the recommended use rates, thiacloprid poses a negligible lethal risk to honeybees when applied either alone or in tank mixes with fungicides of various chemical classes.     

Studies on the sorption of organochlorine insecticides by flour stored on or near treated laminated timber or plywood as used in freight containers

Wood preservatives containing a number of organochlorine insecticides, including aldrin, dieldrin, chlordane and lindane, have been approved in Australia for treating timber used as structural components in cargo containers. Studies on the migration of these insecticides from treated laminated timber and plywood, using commercial containers and in the laboratory, are reported here. The highest insecticide residue levels were found in flour samples stored on newly treated laminated sawn timber. Physical pick-up of insecticide from the surface of the floor was considered to be the major source of contamination. Sorption of insecticides from the atmosphere of the container was the most likely source of contamination in samples stored on or near treated plywood.     

Residues of some chlorinated hydrocarbon pesticides in milk and milk products after their addition to the feed of cows

Lactating cows fed 0.05 part/million aldrin, 0.2 part/million γ-BHC and 2.0 parts/million pp'-DDT in their concentrate ration gave detectable residues of dieldrin, γ-BHC, pp'-DDE, pp'-TDE and pp'-DDT in the milk and also aldrin in the butter and cheese. The levels found after 28 days of feeding were not significantly greater than those after 14 days. Subsequent increase of the pesticide content of the feed increased the residue content of the milk, butter and cheese. Only a small percentage of pesticide residue was found in the buttermilk, separated milk and the whey.     

Interaction between phyllosphere yeasts, aphid honeydew and fungicide effectiveness in wheat under field conditions

Aphid honeydew can reduce fungicide effectiveness against necrotrophic pathogens of wheat under controlled conditions. In 1988 and 1989, field experiments were carried out at different locations in The Netherlands, to assess the interference of honeydew with fungicide effectiveness under field conditions, and to establish whether honeydew consumption by naturally occurring saprophytes could prevent this effect. Different combinations of chemicals were used to create differences in saprophytic population densities and aphid populations, which were expected to result in differences in the amount of honeydew and other nutrients on the leaves. In two of the experiments, Septoria nodorum was the only necrotrophic pathogen present; in the other two the only necrotroph was S. tritici . On several sampling dates, the effect of the fungicides was significantly enhanced by addition of insecticide, most often when the saprophytes were reduced by maneb/anilazine. This effect of insecticide is ascribed to prevention of interference of honeydew with fungicide activity, and not to a direct effect of insecticide, as insecticide alone had no effect on necrosis. On the basis of the fact that interference of honeydew with fungicide activity was most apparent when saprophytic population densities were reduced, it is concluded that the naturally occurring saprophytes can generally prevent the effect of honeydew. The same interactions are likely to occur between other nutrients and fungicides, and it is therefore argued that the naturally occurring saprophytes should be protected by elimination of harmful chemicals.     

Inactivation of seed-treatment fungicides by Rhizobium

2-Methoxyethylmercury chloride (MEMC) applied to cowpea seeds with Rhizobium provided little or no control of seedling rot caused by Rhizoctonia solani; similar treatment, but without Rhizobium, gave >40% control of disease. Treating seeds with quintozene and then with Rhizobium rendered the fungicide completely ineffective against R. solani infections; disease control was >70% when seeds were treated with quintozene only, and >60% when seeds were coated first with Rhizobium and then with quintozene; treatment with quintozene+Rhizobium gave about 25% control. Simultaneous treatment with Rhizobium considerably reduced the efficacy of captafol, chloroneb, carbendazim and thiophanate-methyl. Disease control by carboxin, benomyl and thiabendazole remained unaltered in the presence of Rhizobium, but only thiabendazole gave good control. Seeds treated with MEMC and Rhizobium produced seedlings without root nodules; nodulation was also decreased by captafol and by carboxin but six other fungicides had no effect. The implications of Rhizobium-fungicides interactions are discussed in the context of fungicidal control of root diseases.     

美国果菜类蔬菜2010年农药使用情况分析

美国农业部农业统计中心（National Agricultural Statistics Service,NASS）日前公布了2010年度蔬菜中农药使用情况的统计报告。此报告中的数据采自2010年9月-2011年1月,对19个州的样本进行了统计,考察对象包括29种蔬菜作物。本文依据美国农业部发布的报告,对美国2010年黄瓜、番茄、茄子以及菜用玉米等果菜类蔬菜上常用杀虫剂、杀菌剂和除草剂的使用情况作了详细的计算和分析。按照有效成分统计,黄瓜上使用的杀虫剂有45种、杀菌剂39种、除草剂19种,其中使用最普遍的分别是灭多威、百菌清和乙丁烯氟灵。番茄上使用杀虫剂有34种、杀菌剂23种、除草剂11种,其中使用最普遍的分别是高效氯氰菊酯、百菌清和敌草胺。茄子上使用杀虫剂有24种、杀菌剂17种、除草剂11种,其中使用最普遍的分别是乙基多杀菌素、氢氧化铜和敌草胺。菜用甜玉米上使用杀虫剂有50种、杀菌剂19种、除草剂48种,其中使用最普遍的分别是灭多威、代森锰锌和莠去津。调查数据分析表明,美国在果菜类蔬菜生产中使用的农药品种以传统品种为主。     

Dissipation rates of insecticides in six minor vegetable crops grown on organic soils in Ontario,Canada

Dissipation rates of diazinon, endosulfan, leptophos, methamidophos, methomyl, parathion and pirimicarb were studied on five minor vegetable crops, including cos and head lettuce, endive, cauliflower and Chinese cabbage. Residues from foliar treatment generally followed an exponential rate of decline. The number of days for residues to drop to below acceptable tolerances was highly dependent on the magnitude of the initial residue; large variations in initial residues were observed between years, between insecticides, and between crop types. Residues of five insecticides and two fungicides used in furrow treatments for onions intended for pickling were determined in the onions at harvest and after pickling. Fensulfothion and fonofos levels were below the accepted tolerance of 0.1 mg kg^?1 at harvest, while chlorfenvinphos, chlorpyrifos and ethion were present above this level; fungicide residues were not detected. Following pickling, only ethion residues were still present in the onions at levels greater than 0.1 mg kg^?1.     

Effect of seed treatment in preventing transmission of dwarf bunt of winter wheat to new areas

The effectiveness of various fungicide formulations containing carboxin and thiabendazole in eradicating teliospores of Tilletia controversa (dwarf bunt) from winter wheat seed was evaluated in the laboratory and the field. In the laboratory tests, the viability of teliospores washed from treated infested seed was greatly reduced as compared to the viability of teliospores washed from untreated infested seed, suggesting that carboxin and thiabendazole were primarily fungicidal. Field tests in two different years were established to determine if teliospores from treated infested seed could infect nearby untreated noninfested seed. Formulations containing carboxin were highly effective in reducing infection of healthy seed. No dwarf bunt infected plants developed in either year from seed treated with ‘Vitaflo 250’. Furthermore, seedborne common bunt caused by Tilletia foetida was nearly eradicated by carboxin-containing formulations in one field test. Carboxin treatment of winter wheat seed infested with dwarf bunt teliospores will greatly reduce the danger of introducing this pathogen into new areas.     

保护地常用农药对蜡蚧轮枝菌菌丝生长影响研究

6种杀虫剂和 6种杀菌剂对昆虫病原真菌蜡蚧轮枝菌菌丝生长影响的研究结果表明 ,杀虫剂对蜡蚧轮枝菌菌丝生长有程度不同的抑制作用。在田间常规使用浓度下 ,5种杀虫剂对菌丝生长的抑制率在 10 %以上 ,最高者为甲氰菊酯达 17.6%。田间常规使用浓度稀释 10倍下 ,杀虫剂万灵、快灭净和锐劲特对菌丝生长抑制率低于 5% ,锐劲特在3.3～33.3mg/L时 ,菌丝生长与对照无显著差异 ,表现出与蜡蚧轮枝菌有极好的相容性 ,是菌药混用较好的候选杀虫剂。杀菌剂对蜡蚧轮枝菌菌丝生长有强烈的抑制作用 ,浓度愈高 ,抑制程度愈强。因此 ,在利用蜡蚧轮枝菌防治保护地蔬菜害虫时 ,须与杀菌剂使用保持一定的间隔期     

Transfer of insecticide residues to food stored on or near plywood impregnated with organochlorine insecticides

Formulations of aldrin and dieldrin have been used for a number of years to treat exposed timber components used in the construction of freight containers. The extent to which these insecticides migrate to foodstuffs stored on or near treated plywood has been examined under laboratory conditions and is reported here. A limited survey of organochlorine insecticide residues in samples of foodstuffs, taken from commercial loads carried in freight containers, indicated that residue levels are unlikely to present a health hazard.     

Control of seed-borne Sclerotinia sclerotiorum by fungicidal treatment of sunflower seed

Treatment of sunflower seeds with benomyl, vinclozolin, iprodione or procymidone virtually eliminated seed-borne Sclerotinia sclerotiorum. Applications of fungicides increased the number of surviving seedlings when seeds were sown in vermiculite or in steam-sterilized soil. With the exception of benomyl, fungicides were significantly more effective when applied in acetone solutions than when 100 g a.i./100 kg of seed was applied as conventional dry dressings. There was no difference in effectiveness between the two application methods when the dry dressings were applied at 200 g a.i/100 kg of seed. The acetone infusion method had no deleterious effects on germination of disease-free seed nor on seedling vigour. For a comparable level of control, less fungicide was needed in the infusion treatment than in the dust treatment. If fungicidal treatment of sunflower seeds is used routinely then the introduction of S. sclerotiorum into uninfested land could be controlled.     

Effects of leaf susceptibility and fungicide seed treatment on leaf spot of Pima cotton caused by Altenaria macrospora

Effects of leaf susceptibility and seed treatment with the systemic fungicides tebuconazole (Raxil) or difenoconazole (Dragon) on Altenaria macrospora in Pima cotton were examined under glasshouse conditions and in the field. In the absence of fungicide, the susceptibility of cotyledons to Alternaria- induced shedding increased with seedling age. Effects of seed treatment with fungicide were evident even on the third true leaves, and persisted up to 39 days after planting. Disease suppression was determined both by the fungicide and also by the susceptibility of the host tissue: seed treatment suppressed Alternaria-induced shedding of cotyledons for 18 days, but not 29 days after planting In a field trial, disease progress was delayed by 20-24 days in plots planted with treated seeds. The effect persisted for up to 86 days after planting. Alternaria-induced defoliation at later stages of the season was not affected by the seed treatment. No significant differences in disease control were detected between the two fungicides.     

Effects of some fungicides on Rhizobium trifolii and its symbiotic relationship with white clover

A comparison has been made of the effects of some protective and systemic fungicides, and an eradicant fungicide, on the growth, metabolic activity and nitrogen-fixing capacity of Rhizobium trifolii. Effects on the bacterium grown in vitro with a combined nitrogen source were not necessarily reflected in the nitrogen-fixing capacity of excised nodulated roots of white clover. Symbiotic nitrogen fixation was affected by thiram, oxycarboxin and “Ethylan CP”, but was unchanged by benomyl, captan, carbendazim, carboxin, dodine, dimethirimol, ethirimol, tridemorph, triforine or thiophanate-methyl. None of the fungicides tested altered the leghaemoglobin content of the root nodules.     

辽宁五味子种子带菌检测及药剂消毒处理研究

采用PDA平板检测法对辽宁省6个地区的五味子种子进行带菌检测,并测定了6种杀菌剂对五味子种子的消毒效果。结果表明,五味子种子表面携带的主要真菌类群为曲霉属和青霉属,种子内部寄藏真菌主要包括曲霉属、青霉属、镰刀菌属、根霉属和链格孢属等。供试的6种杀菌剂对五味子种子均有一定的消毒效果,福美双对五味子种子消毒处理效果最显著。     

Field-simulator study of insecticide resistance conferred by esterase-, MACE- and kdr-based mechanisms in the peach-potato aphid,Myzus persicae (Sulzer)

Insecticide sprays were applied to Myzus persicae (Sulzer) populations carrying various combinations of three insecticide resistance mechanisms (esterase-based metabolic resistance and two target site mechanisms, known as MACE and kdr), supported on host plants growing in field simulator cages. The study showed that MACE confers extreme resistance to pirimicarb and triazamate (carbamate insecticides) but not to deltamethrin + heptenophos (16 + 1) (Decisquick) or dimethoate (an organophosphorus insecticide). Resistance to dimethoate depends solely on levels of esterase-based resistance, while resistance to Decisquick depends on kdr and esterase. None of the four insecticides is effective against aphids carrying MACE combined with extreme esterase-based resistance. This knowledge, in association with current monitoring of the mechanisms, will play an important role in making decisions on insecticide use against M persicae in the UK. © 1999 Society of Chemical Industry     

Target and non-target site mechanisms of fungicide resistance and their implications for the management of crop pathogens

Fungicides are indispensable for high-quality crops, but the rapid emergence and evolution of fungicide resistance have become the most important issues in modern agriculture. Hence, the sustainability and profitability of agricultural production have been challenged due to the limited number of fungicide chemical classes. Resistance to site-specific fungicides has principally been linked to target and non-target site mechanisms. These mechanisms change the structure or expression level, affecting fungicide efficacy and resulting in different and varying resistance levels. This review provides background information about fungicide resistance mechanisms and their implications for developing anti-resistance strategies in plant pathogens. Here, our purpose was to review changes at the target and non-target sites of quinone outside inhibitor (QoI) fungicides, methyl-benzimidazole carbamate (MBC) fungicides, demethylation inhibitor (DMI) fungicides, and succinate dehydrogenase inhibitor (SDHI) fungicides and to evaluate if they may also be associated with a fitness cost on crop pathogen populations. The current knowledge suggests that understanding fungicide resistance mechanisms can facilitate resistance monitoring and assist in developing anti-resistance strategies and new fungicide molecules to help solve this issue. © 2023 Society of Chemical Industry.