Field Control Efficacy Research Articles

Bioactivity and Control Efficacy of the Novel Antibiotic Tetramycin against Various Kiwifruit Diseases.

Tetramycin, a novel polyene agriculture antibiotic, has excellent antimicrobial activity against many plant pathogens. In this study, the antimicrobial activities of tetramycin and conventional antibiotics on eight common pathogens and their field control efficacies against four serious diseases in kiwifruit were investigated. The results show that 0.3% tetramycin aqueous solutions (AS) exhibited the superior antibacterial and antifungal activity against Pseudomonas syringae pv. actinidiae, Pseudomonas fulva, Agrobacterium tumefaciens, Botryosphaeria dothidea, Phomopsis sp., Alternaria tenuissima, Armillariella mellea and Phytophthora cactorum of kiwifruit pathogens with EC50 values of 1.21, 1.24, 0.72, 0.14, 0.09, 0.16, 0.06 and 0.17 mg kg−1, respectively. These EC50 values of tetramycin were much higher than those of conventional kasugamycin, zhongshengmycin or polyoxin. Meanwhile, 0.3% tetramycin AS possessed the good field control efficacies for canker, soft rot, blossom blight and brown spot disease of kiwifruit with 74.45, 83.55, 84.74 and 89.62%. Moreover, 0.3% tetramycin AS application notably increased fruit resistance substances contents, activated fruit superoxide dismutase and polyphenoloxidase activities, as well as remarkably enhanced fruit growth, improved fruit quality and storability. This study highlights that tetramycin can be used as a preferred alternative to conventional antibiotics in kiwifruit production.

Deposition distribution, metabolism characteristics, and reduced application dose of difenoconazole in the open field and greenhouse pepper ecosystem

The deposition, dissipation, and metabolism of difenoconazole as well as reduced application dose were studied in the open field and greenhouse pepper system. The deposition amount of difenoconazole gradually increased with the increasing dosages, which followed an order with upper leaf > lower leaf > upper stem > lower stem > cultivated soil > fruit. The dissipation half-lives of difenoconazole in different parts of pepper plant and cultivated soil were higher in the greenhouse than those in the open field. Difenoconazole was transformed to metabolite I (C16H13Cl2N3O2) in pepper plant, but metabolite II (C13H14ClN3O3) in cultivated soil. Additionally, the field control efficacy of difenoconazole at the 0.75-fold minimum recommended dosage could meet the basic control requirement after the first application for 7 d. The results revealed deposition distribution and metabolism characteristics of difenoconazole and the application dose may be effectively decreased in the open field and greenhouse pepper-planted ecosystem.

Evaluation of Botanicals for Management of Piercing-Sucking Pests and the Effect on Beneficial Arthropod Populations in Tea Trees Camellia sinensis (L.) O. Kuntze (Theaceae).

The tea green leafhopper Empoasca onukii Matsuda (Hemiptera: Cicadellidae), the orange spiny whitefly, Aleurocanthus spiniferus (Quaintanca) (Hemiptera: Aleyrodidae), and the green plant bugs Apolygus lucorum Meyer-Dür (Hemiptera: Miridae) are the important piercing–sucking herbivores in tea trees Camellia sinensis (L.) O. Kuntze (Theaceae). The goal of this study was to evaluate the laboratory toxicities and field control efficacies of botanical insecticides including matrine, azadirachtin, veratrine, and pyrethrin to three tea pests. Via leaf-dip bioassay, toxicity tests with botanical insecticides indicated that there were significant differences between the LC50 values for botanical insecticides within the same insect species. Matrine had the highest toxicity to E. onukii, A. spiniferus, and A. lucorum with the LC50 values of 2.35, 13.10, and 44.88 mg/liter, respectively. Field tests showed that, among four botanical insecticides, matrine at dose of 9 g a.i. ha−1 can significantly reduce the numbers of E. onukii and A. spiniferus and the infestation of A. lucorum on the tea plants. Furthermore, botanical insecticides matrine and azadirachtin had no obvious influence on the coccinellids, spiders, and parasitoids densities in tea plantations. The results of this study indicated that use of botanical insecticides, such as matrine, has the potential to manipulate the population of E. onukii, A. spiniferus, and A. lucorum and will be an effective and environmentally compatible strategy for the control of tea pests.

Chemical Nematicides: Recent Research Progress and Outlook.

Plant-parasitic nematodes have caused huge economic losses to agriculture worldwide and seriously threaten the sustainable development of modern agriculture. Chemical nematicides are still the most effective means to manage nematodes. However, the long-term use of organophosphorus and carbamate nematicides has led to a lack of field control efficacy and increased nematode resistance. To meet the huge market demand and slow the growth of resistance, new nematicides are needed to enter the market. The rational design and synthesis of new chemical scaffolds to screen for new nematicides is still a difficult task. We reviewed the latest research progress of nematicidal compounds in the past decade, discussed the structure-activity relationship and mechanism of action, and recommended some nematicidal active fragments. It is hoped that this review can update the recent progress on nematicide discoveries and provide new ideas for the design and mechanism of action studies of nematicides.

Field control efficacy of 12 insecticides and five species of natural enemies to Thysanogyna limbata

Thysanogyna limbata is a pest on the landscape plant Firmiana platanifolia. In this study, we evaluated the control efficacy of twelve insecticides and five common natural enemies to T. limbata. The results showed that the control efficacy of thiamethoxam and imidacloprid to T. limbata was much better than other insecticides. For the three application methods evaluated (spraying, injection, and root-irrigation), the spraying method should be avoided and the injection performed better. If conditions permitted, root-irrigation method could be used as a supplementary method. Among the five natural enemies, Chrysoperla sinica and Lemnia saucia had the best control effect on T. limbata, which could replace insecticide in the long-term control effect. Therefore, C. sinica and L. saucia could be used as safe and environment-friendly pattern to prevent T. limbata in the medium- and long-term in the garden, whereas injection of thiamethoxam and imidacloprid could be used as a short-term and rapid treatment.

Baseline sensitivity and control efficacy of epoxiconazole against Fusarium graminearum in Henan Province, China

Fusarium head blight (FHB), caused by Fusarium graminearum species complex (FGSC) is one of the most destructive wheat diseases worldwide. F. graminearum is the dominant pathogen of FHB in Henan Province. Epoxiconazole is a demethylation inhibitor (DMI) fungicide, and is the main fungicide for controlling FHB in China. In this study, 118 F. graminearum isolates were collected from different regions of Henan Province in 2016 and 2017. The sensitivity of these F. graminearum isolates to epoxiconazole was determined by the method of mycelial growth inhibition. The results showed that the EC50 values range of epoxiconazole to the tested F. graminearum isolates was 0.0196 to 0.5708 μg ml−1, and the mean EC50 value was 0.2178 ± 0.1178 μg ml−1 (mean ± SD). The sensitivity frequency distribution of these F. graminearum isolates to epoxiconazole was a continuous single peak curve, and no isolates resistant to epoxiconazole were found in Henan Province, China. The field control efficacy of epoxiconazole against F. graminearum was evaluated and the results showed that epoxiconazole had a significantly higher control efficacy on FHB, compared to the control fungicide carbendazim. The thousand grain weight of all the fungicide treatments was significantly higher than water control (without fungicide). This study showed that the DMI fungicide epoxiconazole has high activity and field control efficacy on F. graminearum, and can effectively control the prevalence of FHB.

Current status of acaricide resistance in two spotted spider mite, Tetranychus urticae koch and its underlying mechanism

Two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is a serious limiting factor in sustainable production of many crops including vegetables, fruits and ornamentals in protected and open field conditions across the globe. Presently, acaricides are the only option to manage this mite pest. In conventional crop management systems, development of resistance necessitates further applications of acaricides, increasing the use of chemicals and the cost of production of a particular crop; thus becoming a cause of concern to the scientific community. T. urticae is the most notorious species in terms of the total number of pesticides to which its populations have become resistant and is reported to have impaired field control efficacy of all established chemical groups of acaricides, including the organophosphates, carbamates, pyrethroids, chlorinated hydrocarbons, mitochondrial electron transport inhibitors (METI) and other acaricides with novel modes of action. Detoxifying enzymes and resistant genes play major roles in imparting resistance. The paper reviews the acaricide resistance status and the underlying mechanisms of various classes of acaricides against T. urticae.

Deposition, dissipation, and minimum effective dosage of the fungicide carbendazim in the pepper-field ecosystem.

In order to reduce application dosage of carbendazim (CBD), the effects of different droplet sizes and application rate on initial deposition, retention rate, and field control efficacy of CBD in the pepper plant (Capsicum annuum L.) were studied under laboratory and field conditions. Based on eight types of nozzles at six concentrations of 646.8, 582.2, 517.5, 414.0, 310.5, and 258.7 g a.i./hm2 , the initial deposition amount of CBD in the pepper plant showed a first increased and then decreased trend with the increasing application dosages. The initial deposition amount of CBD in the pepper leaves and stems was highest when using the nozzle ST110-03 at 200 μm volume median diameter (VMD) and 350 L/hm2 application rate. HPLC-MS/MS analysis revealed that CBD was first converted to 2-aminobenzimidazole, which then transformed into benzimidazole and 2-hydroxybenzimidazole by deamination and hydroxylation, and ultimately mineralized to carbon dioxide and water via the cleavage of the imidazole ring in pepper plant. The dissipation rate of CBD was fruits > roots/stems > leaves > soils. After 7 days of application, the field efficacy of CBD at six concentrations on pepper anthracnose (Colletotrichum spp.) were 94.1%, 91.3%, 82.3%, 76.5%, 47.0%, and 41.2%, respectively. The results revealed the deposition and dissipation characteristics of CBD, and the minimum effective dosage on pepper anthracnose decreased to 80% of the minimum recommended dose in the open field pepper ecosystem. The study will contribute to the CBD reduction by improving its utilization rate in the pepper-field ecosystem. © 2019 Society of Chemical Industry.

Selection of Antifungal Bacteria <i>Burkholderia lata</i> CAB13001 for Control on Red Pepper Anthracnose and Its Control Efficacy in Field

Selection of Antifungal Bacteria <i>Burkholderia lata</i> CAB13001 for Control on Red Pepper Anthracnose and Its Control Efficacy in Field

Synergistic effect and field control efficacy of the binary mixture of permethrin and chlorpyrifos to brown planthopper (Nilaparvata lugens)

Abstract The brown Planthopper (BPH), Nilaparvata lugens is a major pest of rice production in tropical Asia. The appearance of insecticide resistance challenges the control of BPH in field. The development of new insecticide is expensive and time-consuming. Thus, the precise and proper use of existing compounds becomes an important issue in resistance management of this pest. In this study, five commercial insecticides of BPH (permethrin, chlorpyrifos, imidacloprid, clothianidin and thiamethoxam) were tested to explore the toxicity of the binary mixture between different kinds of insecticides. In all combinations of mixture, the mixtures of permethrin and chlorpyrifos displays synergistic effect at three different mixture ratios (1:1, 1:10 and 10:1). The strongest synergism observed in permethrin/ chlorpyrifos mixtures at 1:1 ratio (Combination index, CI = 0.39). Addition of enzyme inhibitor followed by detoxification enzyme activity assays suggested that the mechanism of synergistic effect of permethrin/chlorpyrifos mixture may result from inhibition of the cytochrome P450 monooxygenase and esterase activity. This inference can be supported through two lines of evidence. One is decrease of toxicity when permethrin/chlorpyrifos mixture in a 1:1 ratio plus triphenyl phosphate (TPP) or piperonyl butoxide (PBO), but increase of toxicity when permethrin/chlorpyrifos mixture in a 10:1 ratio plus TPP or PBO. Another is exposure of the 3rd instar nymphs to permethrin/chlorpyrifos mixture after 72 h also significantly decreased both cytochrome P450 monooxygenases and esterase activity. Further field trail showed the mixture of 50 ppm permethrin +50 ppm chlorpyrifos increased the field control efficiency significantly rather than permethrin alone or chlorpyrifos alone. Our study indicated that the mixture of permethrin and chlorpyrifos in a 1:1 ratio might be an effective method for the control of BPH in paddy field.

Identification and field control efficacy of biocontrol actinomycetes against Heterodera glycines

Identification and field control efficacy of biocontrol actinomycetes against Heterodera glycines

2%阿维&#8226绿僵菌素悬浮剂的研制及田间药效

通过毒力试验、表面活性剂的筛选，确定了2%阿维•绿僵菌素悬浮剂的配方，并进行了质量稳定性和田间药效研究。质量稳定性实验结果表明了2%阿维•绿僵菌素悬浮剂的各项性能稳定。田间试验结果表明，2%阿维•绿僵菌素悬浮剂以有效成分9-11 (ai) g/hm2防治甘蓝小菜蛾，防效可达75.84%~ 93.40%，明显优于1.8%阿维菌素乳油(14(ai) g/hm2)的同期防效，持效期达14天。 The preparation and field efficacy of abamection•destruxin A 2% SC were studied in this paper. According to the laboratory bioassay, there was an obvious synergism effect on Plutella xylostella (L.) mortality, by means of tests of virulence and surface active agents, the formulation of abamection•destruxin A 2% SC was determined. The results of experimental verification of the formulated product demonstrated that all indexes of abamectiondestruxin A 2% SC confirmed to the quality technical standards. Field control efficacy of abamectiondestruxin A 2% SC (9 g/hm2 to 11 g/hm2) against Plutella xylostella (L.) in 14 days of application could reach to 75.84% - 93.40%, which was superior to the efficacy of abamection 1.8% EC (14(ai) g/hm2), and the efficacy could last for 14 days.

Effectiveness of Two Predatory Mite Species (Acari: Phytoseiidae) in ControllingDiaphorina citri(Hemiptera: Liviidae)

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is the insect vector of huanglongbing (HLB), the most devastating citrus disease in the world. The objective of this study was to evaluate the efficacy of two species of commercially available predatory mites, Neoseiulus cucumeris (Oudemans) and N. barkeri (Hughes) (Acari: Phytoseiidae), against D. citri. The predatory mites were evaluated by (1) determining their prey stage preference under no-choice conditions by providing eggs, 1st and 2nd instar nymphs; (2) determining the functional and numerical responses of the predators to varying densities of eggs (from 2 to 32/leaf disk); and (3) evaluating the control effect of N. cucumeris on D. citri on caged trees of Citrus reticulata Blanco in the field, using 1 to 8 sachets (900 ± 100 adult mites per sachet) per tree. The results indicated that N. cucumeris consumed eggs of D. citri only, whereas N. barkeri consumed eggs and 1st instar nymphs. Both predators displayed a Type III functional response (sigmoid). A single female adult of N. cucumeris consumed significantly more D. citri eggs than N. barkeri. N. cucumeris could lay eggs when feeding exclusively on D. citri eggs. The field experiment showed that control effect on D. citri was significantly correlated with the number of N. cucumeris released. Two or more sachets released per tree could achieve significant control at an initial density of 30 adult D. citri (male: female = 1:1) per tree. Improvement of field control efficacy of N. cucumeris on D. citri is discussed.

Biotype and insecticide resistance status of the whitefly Bemisia tabaci from China

Resistance to numerous insecticide classes in Bemisia tabaci Gennadius has impaired field control efficacy in south-eastern China. The biotype and resistance status of B. tabaci collected from these areas was investigated. Two different biotypes of B. tabaci (B-biotype and Q-biotype) were detected in south-eastern China, and the samples collected from geographical regions showed a prevalence of the Q-biotype and the coexistence of B- and Q-biotypes in some regions. Moderate to high levels of resistance to two neonicotinoids were established in both biotypes (28-1900-fold to imidacloprid, 29-1200-fold to thiamethoxam). Medium to high levels of resistance to alpha-cypermethrin (22-610-fold) were also detected in both biotypes. Four out of 12 populations had low to medium levels of resistance to fipronil (10-25-fold). Four out of 12 populations showed low levels of resistance to spinosad (5.7-6.4-fold). All populations tested were susceptible to abamectin. The Q-biotype B. tabaci is supplanting the B-biotype which used to be ubiquitous in China. Field populations of both B- and Q-biotypes of B. tabaci have developed high levels of resistance to imidacloprid and thiamethoxam. Abamectin is the most effective insecticide against adult B. tabaci from all populations.

Comparison of three chemical control strategies for Avena sterilis ssp. ludoviciana

The relatively high cost of Avena sterilis ssp. ludoviciana herbicides makes necessary the development of application strategies that maximize the efficacy with a minimum cost. Three herbicide strategies (spray at full and half doses and patch spray adjusting the doses to A. sterilis density) were compared in relation with control efficacy and crop yield in a winter barley field during three years. The results varied slightly within the years but, in general, the highest control levels and barley yields were obtained with the treatments at full dose. Using half doses reduced both A. sterilis control and barley yields. This effect was mainly attributed to the poor performance of low doses with high weed densities. The site-specific treatments resulted in the highest variability in the control and yield levels, with some control failures in areas of low density of A. sterilis. Barley yields were more affected by the zone effect (position of the plot within the field) than by the weed density effect. This fact was probably attributed to the relatively high heterogeneity in soil fertility within the field. Although the most profitable strategy in this specific situation was treating the whole field at full dose, this was probably due to the high percentage of the field infested by this weed. Different conclusions may be reached under different situations.

Pressão de aplicação com pulverizador de barra e eficiência de bioinseticidas fúngicos comerciais

Bioinseticidas fúngicos são aplicados com pulverizadores convencionais e algumas características destes equipamentos podem não ser adequadas e afetar a eficiência dos bioinseticidas. O objetivo deste trabalho foi verificar se pressões usuais, em aplicações com o pulverizador de barra, podem afetar a ação inseticida de conídios de Beauveria bassiana e Metarhizium anisopliae, componentes de produtos comerciais brasileiros. Para isso, suspensões aquosas de três bioinseticidas foram submetidas à passagem pelo equipamento em três pressões (20, 40 e 60 lbf pol-2) e avaliadas quanto ao rompimento, à viabilidade e à virulência dos conídios. Avaliou-se a viabilidade em lâminas de microscopia cobertas com meio de cultura, após incubação a 26±0,5ºC e fotoperíodo de 12 horas. A concentração foi determinada por meio de contagens em câmara de Neubauer e a virulência foi avaliada para lagartas de Diatraea saccharalis. Não foram encontradas, nos três produtos, influências significativas em nenhum dos parâmetros. Nas pressões avaliadas, a aplicação com o pulverizador de barra não reduz a viabilidade e nem a virulência dos conídios dos bioinseticidas testados, tampouco provoca destruição dos conídios.

Occurrence of resistant strains of Botrytis cinerea to anilinopyrimidine fungicides in table grapes in Chile

Effort to control gray mold caused by Botrytis cinerea failed in a table grapevine ( Vitis vinifera) vineyard near Santiago, Chile where cyprodinil (Vangard 50 WP), a new fungicide of the anilinopyrimidine group, had been applied alone up to four times per year during two growing seasons. A relatively high frequency (38.5%) of resistant isolates of B. cinerea (EC 50 for mycelial growth inhibition varied from 2.9 to 4.84 μg ml −1) may explain the partial loss of field control efficacy obtained. Resistance was correlated with a complete loss of in vivo sensitivity to cyprodinil. Resistant isolates of B. cinerea showed cross resistance to the anilinopyrimidines fungicides mepanipyrim and pyrimethanil. Cyprodinil partially impaired conidia germination and differentially affected conidial germination of resistant and sensitive isolates. Significant differences ( p<0.05) in growth rate, sclerotia production and osmotic sensitivity were found among isolates of B. cinerea, but no correlation could be drawn between these biological differences and resistance or sensitivity. This indicates a disruptive selection characteristic of monogenic resistance. Thus, strategies were implemented to avoid the further development and spread of resistance in B. cinerea to the anilinopyrimidine fungicides. To our knowledge this constitutes the first mention of resistance in B. cinerea populations to anilinopyrimidine fungicides in South America.