Assessment of the abrasion potential of pesticide-treated seeds using the Heubach test

During sowing of pesticide-treated seeds, pesticide-laden dust and abraded seed particles may be emitted to the environment, possibly leading to environmental contamination and posing health risks. In many countries there is currently no legislation concerning the acceptable amount of dust of treated seeds. This study aimed to gain insight in the abrasion potential of available pesticide-treated seeds and its associated factors. The abrasion potential of 45 seed samples of 7 different species (viz. sugar beet, oat, barley, wheat, spelt, pea, and maize) was determined using the Heubach test and amounts of dust were expressed as g 100 kg_seeds^?1, g 100,000 seeds^?1, and g ha^?1. The abrasion potential fell generally within the boundaries of maximum permissible values adopted by different countries. Species, seed treatment company, number of active ingredient (AIs) and combination of AIs had significant effects on the abrasion potential, whereas little or no effect of agitation and conservation was found. However, species were situated differently with respect to each other depending on the unit in which the abrasion potential was expressed. A standard unit that takes into account the species’ seed rate is suggested to give the fairest assessment of dust drift risk and would allow international comparison.     

Pesticidal seed coats based on azadirachtin‐A: release kinetics,storage life and performance

BACKGROUND: Infestation of seeds by pests during storage leads to deterioration in quality. Seed coating is an effective option to overcome the menace. Unlike synthetic fungicidal seed coats, little is known of those based on botanicals. This study aims at developing azadirachtin‐A‐based pesticidal seed coats to maintain seed quality during storage. RESULTS: Polymer‐ and clay‐based coats containing azadirachtin‐A were prepared and evaluated for quality maintenance of soybean seed during storage. Gum acacia, gum tragacanth, rosin, ethyl cellulose, hydroxyethyl cellulose, polyethyl methacrylate, methyl cellulose, polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone and Agrimer VA 6 polymers and the clay bentonite were used as carriers. The time for 50% release (t_1/2) of azadirachtin‐A into water from the seeds coated with the different coats ranged from 8.02 to 21.36 h. The half‐life (T_1/2) of azadirachtin‐A in the coats on seed ranged from 4.37 to 11.22 months, as compared with 3.45 months in azadirachtin‐A WP, showing an increase by a factor of nearly 1.3–3.3 over the latter. The coats apparently acted as a barrier to moisture to reduce azadirachtin‐A degradation and prevented proliferation of storage fungi. Polyethyl methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were significantly superior to the other polymers. Azadirachtin‐A showed a significant positive correlation with seed germination and vigour, and negative correlation with moisture content. CONCLUSION: Effective polymeric carriers for seed coats based on azadirachtin‐A are reported. These checked seed deterioration during storage by acting as a barrier to moisture and reduced the degradation of azadirachtin‐A. Copyright © 2008 Society of Chemical Industry     

An analysis of the persistence and potency of film‐coated seed protectant as influenced by various storage parameters

BACKGROUND: An efficient delivery system for seed‐protectant chemicals is needed in light of several disadvantages of conventional seed treatment methods. This study evaluates the efficacy of film‐coat application in maintaining the persistence and potency of imidacloprid on Lycopersicon esculentum (L.) Mill. seeds after simultaneous storage under ambient and regulated environment in paper and aluminium packages. RESULTS: High‐performance liquid chromatography (HPLC) revealed 0.135 mg kg^?1 of herbage material to be the threshold value beyond which absolute control was obtained, and with film coating the latter was achieved even with half‐dosage seed treatment, irrespective of the storage condition. The technique provided early protection to the crop and also nullified the deleterious effects of ambient storage on the persistence and potency of the pesticide. CONCLUSION: Film coating enabled superior pesticide dosage as well as higher biological efficacy to be achieved. Hence, in addition to being an ecofriendly alternative, the technique would be a more economically viable option for storage of treated seeds. Copyright © 2009 Society of Chemical Industry     

耕作模式和播种方式对旱地小麦产量形成的影响

于2015—2017年在山西省闻喜旱地小麦试验示范基地开展大田试验,以耕作模式为主区,设休闲期深翻和免耕两种模式,以播种方式为副区,设探墒沟播、膜际条播和常规条播3种方式,研究旱地小麦土壤水分、产量形成和经济效益的差异。结果表明：休闲期深翻显著提高旱地小麦播前0～300 cm土壤蓄水效益,达46.97%～240.44%;提高旱地小麦生育时期土壤耗水量,达6.48%～13.07%;提高穗数、穗粒数、千粒重和产量,分别达3.32%～7.22%、3.67%～6.53%、1.11%～3.61%、10.23%～13.16%。探墒沟播和膜际条播较常规条播显著提高了旱地小麦茎蘖成穗率,达5.99%～16.87%,显著提高穗长0.8～1.7 cm,提高可孕小穗数1～3个;提高了穗数、穗粒数,分别达5.28%～15.75%和1.51%～11.25%,此外,休闲期深翻后采用探墒沟播较膜际条播减少投入1 200元·hm^-2,主要是旋耕机械投入、地膜和回收地膜人工投入,增加经济效益622～754元·hm^-2。休闲期深翻后采用探墒沟播较常规条播减少投入300元·hm<...     

A survey of weed seed contamination of rice paddy in Cambodia

Cambodia has experienced a rapid shift from transplanted to hand broadcast seeded rice, with a consequent increase in seeding rates from 25–30 to 100–200 kg ha^?1. To reduce costs, farmers keep their own seed for sowing with the risk of greater weed seed contamination of the sowing seed. A survey of weed seed contamination in harvested rice paddy was conducted in two provinces of Cambodia (Battambang and Takeo) at the end of the wet season in 2016. Farmers were interviewed about rice‐seeding practices, and a total of 110 farmers' fresh paddy samples were inspected for weed seed contamination from the two provinces. Sowing seed samples collected from 28 seed producer lots and 71 samples of farmer‐kept seed were also analysed for weed seed contamination. In both provinces, the majority of farmers kept their own seed or bought seed from a neighbour. Farm‐kept seed for sowing accounted for 88% of sown seed in Battambang and 89% in Takeo. Seeds of 41 different weed species from 13 plant families were found in the farmers' freshly harvested paddy samples. Overall, farmers managed to reduce the number of weed propagules by 60% and seed producers by 95%. There was no significant difference between farmer‐kept seed and seed producer/seed company seed for the total number of weed seeds present. When shown photos, farmers' rankings of the 10 most common weed species found in freshly harvested paddy did not closely correspond to the actual weed seed frequency in the paddy. When farmers were asked to rank the frequency of weeds in their fields without the option to choose from a list, they ranked the weeds differently. Farmers ranked Ischaemum rugosum, Echinochloa spp. and Fimbristylis miliacea as the three most frequent weed species in their fields. The most frequent weeds in harvested paddy, apart from weedy rice, were I. rugosum and Melochia corchorifolia. Farmers did not rank M. corchorifolia as a frequently occurring weed, and most farmers could not recognise M. corchorifolia from photographs. The priority for improved seed hygiene is to place the emphasis on assisting farmers to further improve their seed purification techniques and to caution them to inspect seed before purchasing from neighbours, seed producers and seed companies in the absence of the implementation of seed certification regulation.     

给农业插上科技的翅膀：植保无人机低容量喷雾技术助力农药减施增效

十三五期间以植保无人机低容量施药技术为代表的现代航空植保产业发展迅速。科研协作研究与大量田间试验示范表明,采用植保无人机施药技术能够提高靶标作物上药液沉积量并减少农药流失,实现精准减量施药;同时能够解决地面机具无法作业时的病虫害防治问题。航空植保技术实现了人机分离作业,避免了农药中毒,降低了劳动强度,极大地提高了作业效率,达到减少农药使用量、提高农药利用率的目的。以水稻为对象,综述植保无人机在农药减量、水稻病虫害防效、技术简易性、农药利用率提升、水稻增产以及成本效益提升等发面发挥的作用。航空植保产业的迅速发展加快了植保无人机智能精准控制系统质量的提升和新技术的研发步伐,且植保无人机的普及性提出了飞防药剂、助剂和施药飘移风险控制技术研发的迫切需求,基于此进一步梳理总结了植保无人机低容量喷雾技术在农药减施增效中的作用和未来发展方向。     

农药雾滴雾化沉积飘失研究进展

农药、植保机械与施药技术为植物化学保护的三大支柱,其中施药技术是连接农药学科和植保机械学科的关键环节,是农药从研发到田间应用的“最后一公里”。农药科学使用并不是一个简单的选择农药和施药量的药物学问题,而是涉及作物学、植物保护学、农业工程学、气象学等多学科交叉的系统工程。本文就农药雾滴雾化与运动特性、沉积与分布状态、流失与飘失行为,以及害虫行为与农药雾滴雾化运动和沉积分布关系等方面的研究进展展开综述,总结该方面的理论与实践经验,可为提高植保机械水平与施药质量、提高农药利用率与防治效果、减轻农药负面影响、提高粮食与食品安全提供参考。     

Seed degeneration in potato: the need for an integrated seed health strategy to mitigate the problem in developing countries

Seed potato degeneration, the reduction in yield or quality caused by an accumulation of pathogens and pests in planting material due to successive cycles of vegetative propagation, has been a long‐standing production challenge for potato growers around the world. In developed countries this problem has been overcome by general access to and frequent use of seed, produced by specialized growers, that has been certified to have pathogen and pest incidence below established thresholds, often referred to as certified seed. The success of certified seed in developed countries has concentrated the research and development agenda on the establishment of similar systems in developing countries. Despite these efforts, certified seed has had little penetration into the informal seed systems currently in place in most developing countries. Small‐scale farmers in these countries continue to plant seed tubers acquired through the informal seed system, i.e. produced on‐farm or acquired from neighbours or local markets. Informal seed tubers frequently have poor health status, leading to significant reductions in yield and/or market value. This review emphasizes the need to refocus management efforts in developing countries on improving the health status of seed tubers in the informal system by integrating disease resistance and on‐farm management tools with strategic seed replacement. This ‘integrated seed health strategy’ can also prolong the good health status of plants derived from certified seed, which would otherwise be diminished due to potential rapid infection from neighbouring fields. Knowledge gaps, development challenges and impacts of this integrated seed health strategy are discussed.     

三唑酮种衣剂在小麦种表的超微分布及抗脱落淋失研究

 应用扫描电镜观察到三唑酮种衣剂(Tri SCF)以具网眼结构的膜状物包被于小麦种子表面,膜状物厚度约4~7.5μm,种表包被率达95%;对照处理三唑酮可湿性粉剂(TriWP)拌种在小麦种表呈点状或片状零散分布,种表被药剂覆盖率低于80%。振荡试验中TriSCF包衣药剂脱落率为2%,显著低于TriWP干拌种(43%)或湿拌种(25%)。放射性同位素示踪检测表明,TriSCF包衣处理的小麦种子在17%含水量砂床上发芽1~7d内,保持种子内的¹⁴C-二唑酮放射性强度显著高于TriWP拌种处理,而然失到砂床上的¹⁴C-三唑酮放射性强度低开Tri WP拌种处理。     

Secondary dispersal, spatial dynamics and effects of herbicides on reproductive capacity of a recently introduced population of Bromus sterilis in an arable field

An arable field was subdivided and subjected to either deep inversion ploughing or non‐inversion cultivation after viable seeds of Bromus sterilis had been sown into oilseed rape stubble. After sowing in isolated plots distributed within the field, sequences of cropping treatments for the establishment of two successive winter wheat crops were applied. Each subfield was split into an uphill and a downhill direction for soil cultivation. The field had a 10° slope. In the season following seed introduction, 2.6% of the introduced seeds had successfully germinated and established in the non‐inversion cultivation regime, when no effective graminicide was applied. Ploughing eradicated B. sterilis. Using differential global positioning system (DGPS) mapping of the whole field population, emerged plants were observed up to 8.7 m (uphill treatment) and 21.3 m (downhill treatment) of their initial source. The median distance seeds were transported was 2.3 m uphill and 4.8 m downhill. Post‐emergence application of the herbicide propoxycarbazone slightly reduced weed density and seed weight, and almost halved weed seed production. Application of fenoxaprop‐P‐ethyl was followed by higher density of plants, tillers and seeds of B. sterilis. Seed viability was unaffected by herbicide use. Thus, in the second wheat crop following seed rain, the weed population was dispersed more widely in the field, such that 20–30% of seeds were dispersed more than 5 m distance from the first year's foci of infestation. The relevance of soil cultivation to secondary dispersal of B. sterilis is discussed.     

Integrated management of Bromus diandrus in dryland cereal fields under no‐till

As herbicides have limited effect in controlling Bromus diandrus in no‐till dryland cereal fields, the integration of chemical and cultural methods needs to be investigated. A field study was carried out in Lleida (Spain) during 2008–09, 2009–10 and 2010–11 seasons, in a no‐till winter cereal field integrating delayed crop sowing with herbicides in a barley–wheat–wheat rotation. Three crop sowing dates were considered: D1, mid‐October; D2, mid‐November; and D3, early December, and the herbicides mesosulfuron‐methyl plus iodosulfuron‐methyl‐sodium were applied in wheat. Weed density, cumulative emergence and fecundity were estimated for each sowing date. In all three seasons, a significant reduction in the cumulative emergence of B. diandrus as compared to D1 was observed in D2 (82.0, 97.5 and 98.1%) and D3 (80.8, 98.7 and 97.2%). In addition, a significant decrease in weed density and seed rain was observed across all sowing dates and seasons. The herbicide used in wheat was more effective under delayed sowing, due to lower weed density and presence of less developed weed seedlings. After three seasons, the populations of B. diandrus were completely depleted in D2 and D3. This study demonstrates the possibility of eliminating brome infestations in dryland cereal fields in no‐till systems through the integration of cultural and chemical strategies.     

Availability of pesticide-treated seed on arable fields

A study of the availability of pesticide-treated seed on arable fields was performed. The research was carried out in three different areas of The Netherlands (soil types ranging between sand and heavy clay) and included the following topics: drilling techniques, soil conditions, location on the field and spillage. The results show that there is a large variation among the various crops in the percentage of seed remaining on the soil surface. This is mainly caused by differences in drilling techniques and soil conditions. The percentage of surface seeds after standard drilling is approximately four times higher than after precision drilling. The best correlation for the impact of soil conditions was found for the overall measure of clod weight. Large differences in seed densities (factor of 3.5) were found between the headland and the field centre. Spillage occured in most crops investigated, with an average of two spills per field. Based on the field data it is recommended to use in the current risk assessment for birds and mammals the following percentages of seed remaining on the soil surface: 0.5% for precision drilling, 3.3% for standard drilling in spring and 9.2% for standard drilling in autumn.     

吉林省向日葵菌核病综合防治措施研究及大面积应用效果

在重茬4年的重病地块晚播(5月20日—25日)向日葵,其花腐型菌核病比正常播期(4月25日)减少90％以上,而产量提高13％—30％。在农村扩大示范,晚播(5月19日)减少病害59％—75％,产量提高35％。在盛花期—成熟期喷2—3次50％速克灵500倍液可大大减轻花腐型菌核病的发生(防治效果65.9％—92.3％)。经筛选以速克灵(0.5％)拌种防治根腐型菌核病效果最好,在温室中对土壤和种子中的病菌防治效果达83％以上,小区试验和农村示范防治效果达55.8％—100％。土壤中增施钾肥可提高植株抗病力,减轻发病。1990年在吉林省农安、长岭2县8533ha采用晚播、轮作2年以上、种子处理、增施钾肥、盛花期—成熟期喷药的一套综合防治措施,重点调查10块对比田,花腐型菌核病平均防治效果为87.62％(63.38％—100％),对根腐型菌核病防治效果平均为66.77％(50.0％—82.57％)。1991年在长岭、农安等6个主产区推广6.37万ha,重点调查134块对比田,花腐型菌核病防治效果平均为75.86％(46.37％—100％),根腐型菌核病平均防治效果为65.11％(33.33％—100％),增产增收显著。     

Relative contribution of genotype, seed size and environment to secondary seed dormancy potential in Canadian spring oilseed rape (Brassica napus)

Secondary seed dormancy has been linked to seedbank persistence of volunteer oilseed rape (Brassica napus) in western Canada. It has been suggested that there is a genetic component to secondary seed dormancy expression in oilseed rape, but little is known of its importance in relation to non‐genetic factors. In a series of experiments we investigated the relative importance of genotype, seed size, time of windrowing and pre‐ and post‐harvest environment on the expression of secondary seed dormancy. We found that genotype contributed between 44 and 82% to the total variation in secondary seed dormancy. A broad range in secondary seed dormancy expression was observed among 16 genotypes examined. Nevertheless, three‐quarters of the genotypes investigated exhibited relatively high potential for the expression of secondary seed dormancy (back‐transformed mean 71% dormant seeds). Seed size contributed 21% to the total variation, while the influence of seed maturity (harvest regime) on secondary seed dormancy expression was negligible. Despite diverging environmental conditions during the four growing seasons spanning these experiments, the influence of pre‐harvest environment on seed dormancy expression was relatively small and ranged from 0.1% to 4.5%. Secondary seed dormancy potential decreased over time during seed storage. This decrease was greatest when seeds were stored at ambient temperatures and least when seeds were stored at ?70°C.     

Pesticide buffer zones for the protection of wildlife

Buffer zones can play important roles in agricultural habitats, both in the protection of off-crop habitats from pesticide and fertiliser drift and run-off, and in providing important areas of non-crop habitats. Their role in the protection of aquatic habitats from pesticide drift is a significant feature of pesticide risk management, but they are currently used only to a limited degree to protect terrestrial habitats. This paper summarises some of the evidence for the risks and impacts of pesticide drift into non-crop habitats, and the approaches taken by the nature conservation agencies in deriving buffer zones for the protection of sites that are important for nature conservation. Biodiversity objectives need to be explicitly built into ICM programmes, and buffer zones, together with appropriate application technology, can play an important part in reducing pesticide drift in ICM systems to achieve such objectives.     

三唑酮种子包衣对冬小麦种子萌发和幼芽抗逆因子的影响

为评价三唑酮种子包衣对冬小麦种子萌发的安全性,以苯醚甲环唑为对照药剂,研究了不同包衣剂量三唑酮对周麦22和铭贤169小麦种子发芽及周麦22抗逆相关生化因子的影响。结果表明:周麦22和铭贤169小麦种子发芽指数、种子活力指数和发芽率均与三唑酮包衣剂量呈负相关,且符合指数方程Y=A+B×e(-x/k),但铭贤169种子发芽指数、种子活力指数和发芽率对三唑酮剂量变化更敏感;三唑酮种子包衣能引起小麦幼芽体内赤霉素(gibberellins,GAs)含量降低和脱落酸(abscisic acid,ABA)含量升高,且GAs含量下降程度和ABA水平升高程度均随三唑酮包衣剂量的增加而增加,从理论上解释了三唑酮可对小麦种子萌发产生抑制作用且抑制作用与包衣剂量相关的原因。但通过对幼芽相关抗逆因子的研究表明,三唑酮包衣有利于新长成幼芽中叶绿素含量、根系呼吸速率、可溶性蛋白质含量和α-淀粉酶活性的增加以及细胞膜通透性降低,说明三唑酮包衣在一定程度上有助于新长出幼芽抗逆性的增加。相比之下,苯醚甲环唑对小麦种子萌发的抑制作用比三唑酮小,且更有利于幼芽抗逆性增加。     

A review of the effects of crop agronomy on the management of Alopecurus myosuroides

This study reviews 52 field experiments, mostly from the UK, studying the effects of cultivation techniques, sowing date, crop density and cultivar choice on Alopecurus myosuroides infestations in cereal crops. Where possible, a statistical meta‐analysis has been used to calculate average responses to the various cultural practices and to estimate their variability. In 25 experiments, mouldboard ploughing prior to sowing winter cereals reduced A. myosuroides populations by an average of 69%, compared with non‐inversion tillage. Delaying drilling from September to the end of October decreased weed plant densities by approximately 50%. Sowing wheat in spring achieved an 88% reduction in A. myosuroides plant densities compared with autumn sowing. Increasing winter wheat crop density above 100 plants m^?2 had no effect on weed plant numbers, but reduced the number of heads m^?2 by 15% for every additional increase in 100 crop plants, up to the highest density tested (350 wheat plants m^?2). Choosing more competitive cultivars could decrease A. myosuroides heads m^?2 by 22%. With all cultural practices, outcomes were highly variable and effects inconsistent. Farmers are more likely to adopt cultural measures and so reduce their reliance on herbicides, if there were better predictions of likely outcomes at the individual field level.     

几种化学药剂对瑞典蝇的防治效果比较

为明确药剂拌种对小麦瑞典蝇的防治效果,对吡虫啉、七氟菊酯等6种常用拌种剂进行了药效对比试验。结果显示,以0.2％吡虫啉效果最佳,播种30 d后调查,防效仍在90.85%,且对出苗有一定促进作用。七氟菊酯的持效期也较长,播种30 d后调查,0.1%、0.2%和0.3%3种剂量的防效均在80%以上。播种后13 d调查,以0.3%七氟菊酯防效最高,其次为0.2%吡虫啉,分别为96.60%和93.01%,但前者对出苗有较强抑制作用,相对出苗率较对照降低31.39%。     

Contaminant seeds in imported crop seed lots: a non‐negligible human‐mediated pathway for introduction of plant species to islands

Contaminant seeds in crop seed lots constitute a pathway for plant species introduction into new areas, and these non‐native weeds may be an environmental problem if they become invasive. Seed certification is a process that regulates and guarantees the quality of seed lots, including their purity. In this study, we assessed weed contamination in certified and non‐certified seed lots (n = 116) from 12 crop species commonly cultivated in the Balearic Islands. Contaminant seeds were separated using sieves, and then manually under a stereomicroscope, before they were germinated to confirm taxonomic identity. Weight, number and diversity of the contaminant seeds per kilogram of seed lot, number released per hectare according to sowing rate, and taxonomic identity and biogeographical origin of contaminant species were recorded. Although certification reduced the number of contaminant seeds in the seed lots, it did not entirely eliminate contaminants, because we found up to 2000 contaminant seeds kg^?1 of certified ryegrass and sulla. Overall, contaminant seeds represented 118 taxa; of which, 82 were identified to species level, 70% of species were native, 19% were cultivated, and 11% were non‐native. Two of the identified taxa were first records for the Balearic Islands. In conclusion, contaminant seeds in imported crop seed lots represent a non‐negligible pathway for plant species introduction.     

Chemical control of weedy rice in precise hill‐direct‐seeded rice in South China

Precise hill‐direct‐seeded rice, which is both cost‐ and labor‐saving, is based on the direct seeding of rice by using a precision rice hill‐drop drilling machine. Weedy rice (Oryza sativa f. spontanea), also known as “red rice”, is a major weed in precise hill‐direct‐seeded rice, causing an ≤80% yield loss and a reduction in grain quality. The aim of this study was to evaluate the control efficiency of weedy rice by pretilachlor (a pre‐emergence herbicide) and fenclorim (a safener) and their safety for precise hill‐direct‐seeded rice in two consecutive years. The amount of rice seed germination was accelerated by soaking the seeds in the safener at 0.67 g ai L^?1 for 1 h before sowing. The pre‐emergence pretilachlor treatments were applied 2 days after sowing cultured rice. The inhibition of the shoot fresh weight of the cultured rice was reduced by 3.3, 6.4 and 7.4% with 450, 900 and 1350 g ai ha^?1 of pretilachlor at 32 days after sowing (DAS) and that of the root fresh weight was reduced by 2.6, 4.9 and 8.1%, respectively. With fenclorim and pretilachlor in a precise hill‐direct‐seeded rice field in 2010 and 2011, the weedy rice control efficiency at 32 DAS was reduced by 100 and 98.0%, respectively. The pre‐emergence pretilachlor treatments that were applied at 2 DAS were much more efficient in the weedy rice control and less inhibitory to the cultured rice growth. The rice yield was increased by 26.1–26.7% in the mechanical precise hill‐direct‐seeded rice, relative to the manual‐seeding rice, with the application of fenclorim and pretilachlor.