Chemical control

Top PDF Chemical control:

Postharvest biological control of brown rot in peaches after cold storage preceded by preharvest chemical control

Postharvest biological control of brown rot in peaches after cold storage preceded by preharvest chemical control

Chemical control is the most widely adopted method, with sprays of fungicides from flowering to pre harvest, and the iprodione products triforine, procymidone, captan, mancozeb are recommended for disease control (May-De Mio et al., 2004). May-De Mio et al. (2011) attributes the preference for the chemical control because of its easiness of use and efficiency to control brown rot, mainly tebuconazole and azoxystrobin. However, the use of the same active ingredient for a few cultivations can promote resistance (Luo & Schnabel, 2008). In spite of all benefits that the fungicide bring to brown rot control, its use is very controversial and it is not allowed during postharvest life because it can harm consumers’ health (Adaskaveg & Förster, 2010). During postharvest (storage time), the fungi have an appropriate environment for development and increase brown rot incidence. This fact highlights the need to develop new techniques for brown rot control throughout postharvest. One technique that requires more studies is the biological control with Trichoderma spp., basically because its use is allowed during the postharvest (storage time). It is an anamorphic fungus found in most types of soil (Harman et al., 2004), the fungus has an antagonistic
Mostrar mais

7 Ler mais

Chemical control of different digitaria insularis populations and management of a glyphosate-resistant population

Chemical control of different digitaria insularis populations and management of a glyphosate-resistant population

Despite the difficulty of chemical control of adult plants of D. insularis, satisfactory results are obtained using higher doses of glyphosate or its association with other herbicides (Procópio et al., 2006). However, in some agricultural areas of South-Central Brazil, adult populations of this species have required even larger dosages without success in controlling (Correia & Durigan, 2009). In the Brazilian city of Jaboticabal, SP, these authors have reported that the application of 2.88 kg a.e. ha -1 of glyphosate was not effective

9 Ler mais

Lack of correlation between micro fungi species and chemical control method of Atta treated with toxic baits

Lack of correlation between micro fungi species and chemical control method of Atta treated with toxic baits

The correct identification of fungal species is important for understanding the ecological relationships in ant colonies. Morphological descriptions of fungi represent the major source of information for species identification; however, morphological characters alone can be problematic due to the difficulty in identifying fungal structures (revised by BEGEROW et al., 2010). Molecular identification by DNA barcoding has been intensively used and the “internal transcribed spacer” (ITS) region of ribosomal DNA (rDNA) is the official marker for DNA barcoding of fungi (BEGEROW et al., 2010; SEIFERT, 2009; XU, 2016). Currently, there are over 100,000 fungal ITS sequences generated by Sanger sequencing, deposited in the NCBI and other databases, which can be used for molecular identification of fungi. In this study, we used DNA barcoding to identify fungi in ant colonies treated with toxic baits, associating with chemical control method with.
Mostrar mais

6 Ler mais

Chemical control of morning glory as a function of water restriction levels

Chemical control of morning glory as a function of water restriction levels

The success of chemical control depend on soil type, availability of soil moisture, and species selection (Schroeder, 1988). Previous work has shown that control with pre- emergence herbicides is possible, but seed germinating at depth, or in dry or cloddy soils, are not controlled as effectively (Garrett & Orson, 1989). Furthermore, the persistence of herbicides in the soil varies according to the chemical structure of molecule, soil type, and climatic conditions, such as moisture, which affects adsorption, lixiviation and microbial and chemical decomposition (Silva et al., 1999). Herbicides require moisture in soil for its molecules to become available in the soil solution and then eventually be absorbed by weeds (Martini & Durigan, 2004). Chemical control is more effective if spraying is conducted during the rainy season, due to soil moisture and the intense metabolism of weeds, which helps in the absorption of most herbicides authorized for sugarcane crop, since they are highly soluble in water (Rodrigues & Almeida, 2011). However, there are also products on the market that are also efficient during the dry season. In recent studies Negrisoli et al. (2011) and Toledo et al. (2010) documented great weed control with amicarbazone, isoxaflutole, diuron and hexazinone, due to favorable physical and chemical characteristics like high water solubility and low adsorption capacity of clay particles and organic matter.
Mostrar mais

9 Ler mais

Terpenes with insecticidal activity: an alternative to chemical control of insects.

Terpenes with insecticidal activity: an alternative to chemical control of insects.

inorganic compounds have declined drastically and natural products, as well as synthetic derivatives, have been widely used instead. The search for natural alternatives have improved the development of bench top bioassays and an array of synthetic approaches for known and novel natural products that shows relevant activities as feeding supressors and deterrents. The studies concerning mode of action and environmental impact of these substances, that may be biodegradable and selective for undesired insects, had led to the evaluation and discovery of a number of molecules, mostly terpenoids and alkaloids, that are well reported as candidates for inseticidal compounds that could be an effective alternative for insects control with a lower impact on human health, household animals and the environment.
Mostrar mais

11 Ler mais

ABSTRACT Chemical control of Commelina erecta L. in trangenic soybean

ABSTRACT Chemical control of Commelina erecta L. in trangenic soybean

En siembra directa, algunas malezas han demostrado cierta tolerancia a los controles de presiembra con glifosato + 2,4-D, a las dosis difundidas en la zona (dependiendo el grado de control de las condiciones ambientales y edáficas y del tamaño de las mismas). Entre estas se puede citar a Commelina sp. (Ricci, 1994).

6 Ler mais

Controle químico associado à roçada de soqueiras do algodoeiro / Chemical control associated to mowing of cotton stalks

Controle químico associado à roçada de soqueiras do algodoeiro / Chemical control associated to mowing of cotton stalks

The objective of this work was to evaluate potential management strategies for control cotton stalks using herbicide treatments associated to mowing. The experiment was conducted in the field from August to December 2013, installed at the end of the development cycle of the cotton crop in a factorial scheme (28x2) with subplots, in a randomized complete block design with four replications (one or two sequential application). The factor analyzed in the plot was constituted by herbicide treatments and the factor analyzed in the subplots was the number of applications of the treatments after the mechanical control. The evaluated variables were the percentage of visual control, the number of regrown plants and the size average of the regrowth. Only one application of the herbicide treatments did not promote satisfactory control of the cotton stalks. The treatments with 2,4-D + glyphosate + saflufenacil + [imazapic + imazapyr], glyphosate + saflufenacil + fluroxypyr and glyphosate + dicamba + saflufenacil, promoted total control of the cotton stalks (100%) at 21 days after sequential application and did not present regrowth plants until the last evaluation date, and were, therefore, the most efficient treatments to control cotton stalks.
Mostrar mais

15 Ler mais

Phytosociology of weed in the southwestern Goiás region

Phytosociology of weed in the southwestern Goiás region

chemical control methods and weed management in the southwest region of Goiás State, Brazil. Considering these changes, this study aimed to perform a phytosociological survey in areas with glyphosate resistant soybeans and conventional soybeans as the main harvest and sorghum, maize, millet or fallow in succession as the second harvest. A multivariate matrix of the floristic composition was constructed, and the indicator values of the individual number and dry biomass of species were measured. Based on the number of individuals, the species Chamaesyce hirta, Bidens subalternans, and Cissampelos ovolifolia were typical of areas cultivated with glyphosate-resistant soybean, while Euphorbia heterophyla presented indicator values of areas with conventional soybean cultivation. During the second harvest period, significant indicator values were observed for Crotalaria spectabilis in maize areas, Cenchrus echinatus in sorghum, and Commelina benghalensis, Sida glaziovii, Ipomoea grandifolia, Sida rhombifolia, and Ipomoea cordifolia in areas with millet. The species Conyza bonariensis was typical in the period before the herbicide application at post-emergence in harvest. Volunteer soybean presented as typical for the period before the herbicide application at post- emergence in the second harvest. Weeds that were difficult to control or were tolerant and resistant to the herbicide applications were recorded in the areas studied.
Mostrar mais

11 Ler mais

Marinês Bastianel1 , Juliana Freitas-Astúa 1,2 , Elliot Watanabe Kitajima3 Marcos Antonio Machado1

Marinês Bastianel1 , Juliana Freitas-Astúa 1,2 , Elliot Watanabe Kitajima3 Marcos Antonio Machado1

During the rainy season, when relative humidity is higher (October to March in the Southeast Brazil), the number of mites tends to drop. From April to September (dry season), the mite population reaches its peak (66). Besides the environmental conditions, the presence of predators and pathogens of the vector and the management of the orchard (use of fertilizers and chemicals such as pesticides etc.) can also affect the mite population fluctuation on the flat mite in citrus orchards (1, 66). Studies on the spatial patterns of the B. phoenicis and citrus attacked by leprosis in the citrus orchards revealed that there are aggregations of infected plants but this pattern does not overlap with the aggregation of mite infested plants (3). This observation has implications in the chemical control procedures. Presently acaricide spraying to prevent leprosis is made according to thresholds in mite population, which would be justifiable only if the presence of the disease is confirmed.
Mostrar mais

10 Ler mais

LOAD-BEARING CAPACITY OF A RED-YELLOW LATOSOL CULTIVATED WITH COFFEE PLANTS SUBJECTED TO DIFFERENT WEED MANAGEMENTS

LOAD-BEARING CAPACITY OF A RED-YELLOW LATOSOL CULTIVATED WITH COFFEE PLANTS SUBJECTED TO DIFFERENT WEED MANAGEMENTS

It is essential to know the levels of pressure applied to the soil by different weed managements to adapt the management of coffee plantations in a sustainable manner. The objectives of this study were: a) to generate load-bearing capacity models of a Red-Yellow Latosol (Oxisol) submitted to different weed managements and b) to determine which weed management resulted in higher compression. The study was conducted at the Experimental Farm of EPAMIG, located near the community Farias, in Lavras-MG (latitude 21° 14’ 43" S and longitude 44° 59’ 59" W and altitude of 919 m). The soil is a Red-Yellow Latosol (LVA) cultivated with coffee plantation using Topazio MG 1190 coffee variety, since 2006. We evaluated five weed managements, three being through mechanical control (harrow (GD), mowing (RÇ) and brush (TC)) and two by chemical control (post-emergence herbicide (HPos) and pre emergence herbicide (HPre)). To obtain the load-bearing capacity models, 10 undisturbed soil samples were randomly collected in the 0-3, 10-13 and 25-28 cm layers between the rows. The load-bearing capacity models which indicated a higher compaction were: in the 0-3 cm layer, TC and GD; in the 10-13 cm layer, HPre, HPos and RÇ and in the 25-28 cm layer, GD. The load-bearing capacity models that indicated greater susceptibility to compaction were: in the 0-3 cm layer, HPos; in the 10-13 cm layer, GD and TC and in the 25-28 cm layer, HPre.
Mostrar mais

7 Ler mais

Epidemiology and strategies for chemical management of powdery mildew in mango

Epidemiology and strategies for chemical management of powdery mildew in mango

Abstract – The objective of this work was to evaluate phytosanitary strategies for the chemical control of powdery mildew (Oidium mangiferae) in mango, based on the alternation of active ingredients with different modes and sites of action, and to determine the environmental and epidemiological conditions that favor the development of the disease. The experiment was conducted in Guerrero, México, in commercial orchards, within a program for the development of fungicide spraying strategies. Epidemic curves were used on temporal analyses of the disease for: incidence; area under disease progression curve (AUDPC); severity; and conidial seasonality and its relationships with meteorological parameters. The disease was better controlled with the application of systemic fungicide followed by contact fungicide with multisite activity. The first symptoms appeared 30 days after the issuance of shoots, and the most susceptible phenological (critical) stages were at full bloom and at the onset of fruit with 8–15 mm. Optimum conditions for the development of powdery mildew, which maximizes the density of airborne spores, are temperatures higher than 30°C and relative humidity over 90%.
Mostrar mais

9 Ler mais

Commercial Biological Control Agents Targeted Against Plant-Parasitic Root-knot Nematodes

Commercial Biological Control Agents Targeted Against Plant-Parasitic Root-knot Nematodes

Root-knot nematodes are microscopic round worms, which cause severe agricultural losses. Their attacks affect the productivity by reducing the amount and the caliber of the fruits. Chemical control is widely used, but biological control appears to be a better solution, mainly using microorganisms to reduce the quantity of pests infecting crops. Biological control is developing gradually, and with time, more products are being marketed worldwide. They can be formulated with bacteria, viruses or with filamentous fungi, which can destroy and feed on phytoparasitic nematodes. To be used by the farmers, biopesticides must be legalized by the states, which has led to the establishment of a legal framework for their use, devised by various governmental organizations.
Mostrar mais

11 Ler mais

Int. braz j urol.  vol.42 número1

Int. braz j urol. vol.42 número1

Our encouraging results are in concordan- ce with the experience of other institutions (15- 19). Multivariate and univariate analyses show that the pretreatment PSA level, Gleason score and T stage were not a significant variable for bio- chemical control. In the present series, hormonal ablative treatment was given for 3-4 months and did not improve biochemical control.

6 Ler mais

D OSE -R ESPONSEC URVES OF Lolium multiflorumB

D OSE -R ESPONSEC URVES OF Lolium multiflorumB

ABSTRACT - Chemical control with herbicides, especially glyphosate, is the main method used to control ryegrass. However, the repeated use of glyphosate has selected resistant ryegrass biotypes. Thus, the ACCase inhibitor herbicides have become the main alternative to control glyphosate-resistant biotypes, being widely used by farmers in Rio Grande do Sul. Repeated use of ACCase inhibitors, in turn, have selected ryegrass biotypes resistant to this herbicide mechanism. Thus, the objective of this study was to evaluate the response of ryegrass biotypes to different clethodim rates by dose-response curves. Increasing doses (0, 12, 24, 48, 72, 96, 144 and 192 g a.i. ha -1 ) of the herbicide clethodim were applied at the 3-4
Mostrar mais

6 Ler mais

JL Sívori, N Casabé, EN Zerba, EJ Wood+

JL Sívori, N Casabé, EN Zerba, EJ Wood+

role of GST induction in turning on the detoxify- ing enzymes enhancing the defense machinery, speeding the development of resistance and caus- ing cross-tolerance to other pesticides (Anspauch et al. 1994, Hinkle et al. 1995, Carlini et al. 1995). Searching selective insecticide synergists for chemical control of Triatominae, we have studied the distribution and properties of GST from T. infestans (Wood et al. 1986a) and have found natu- ral products of flavonoid type such as gossypol and quercetin and some triphenylmethane dyes (Thy- mol blue) capable of inhibiting in vitro T. infestans GST (Wood et al. 1990). Currently we have stud- ied the mechanism of synergism of fenitrothion due to GST inhibitors in T. infestans (Sivori 1993).
Mostrar mais

6 Ler mais

IMPLEMENTATION OF A SAFETY PROGRAM FOR THE WORK ACCIDENTS’ CONTROL. A CASE STUDY IN THE CHEMICAL INDUSTRY

IMPLEMENTATION OF A SAFETY PROGRAM FOR THE WORK ACCIDENTS’ CONTROL. A CASE STUDY IN THE CHEMICAL INDUSTRY

ensuring the safety, occupational health and sustainability, as a basic requirement to release the financial resources, is being fundamental for the evolution of these values inside the organizations, mainly in the developing countries, where there is a lack of a proactive legislation and an effective and responsible government oversight. However, this symbol of success was not reflected in the drop of the number of accidents, since, according Campos and Medeiros (2009, p. 71), the organizations are searching for the implementation of their management system in health and safety at work to meet the clients demands and the legislation, forgetting the primordial, which is control their accidents’ risks and occupational diseases, in order to improve their performance in Work Health and Safety (WHS).
Mostrar mais

18 Ler mais

Chemical and ecological control methods for Epitrix spp.

Chemical and ecological control methods for Epitrix spp.

In Portugal, the worst economic damage occurred in 2008 when whole consignments of potatoes sent for processing in France, Spain and other countries were rejected. In 2009, growers applied additional early sprays of insecticides (mainly the neonicotinoid insecticide, acetamiprid and the synthetic pyrethroid, bifenthrin) and there were fewer reports of economic tuber damage (Boavida et al., 2013). Field observations suggest that if 2-3 early insecticide sprays are applied in addition to early applications for the normal Colorado beetle spray programme, the tuber damage is usually kept below 2-3%. However when no insecticide sprays are applied, 80% tuber damage can commonly occur. In the UK, ware crops receive on average only one insecticide spray and if Epitrix potato flea beetles were to become established, insecticide inputs would undoubtedly have to increase, especially for crops where market requirements dictate that even low levels of tuber damage are deemed unacceptable (Malumphy et al., 2010; Eyre and Giltrap, 2012; Cuthbertson, 2014). Other important elements of control include the maintenance of an adequate rotation between potato crops (3 years) and the control of volunteers and host weeds during the intervening period. At present, the use of botanical insecticides in the regulation of several pests in crops is gaining interest (Isman, 2006). The plant extracts obtained from the Neem tree (Azadirachta indica) have been the most studied in the last few years. Their effectiveness is widely proved in the control of insects, acari, and nematodes (Hernández
Mostrar mais

3 Ler mais

Rev. Soc. Bras. Med. Trop.  vol.47 número6

Rev. Soc. Bras. Med. Trop. vol.47 número6

Introduction: This study was conducted in Brazil and Colombia,where dengue is endemic and vector control programs use chemical insecticides. Methods : We identifi ed knowledge, attitudes, and practices about dengue and determined the infestation levels of Aedes aegypti in one Brazilian and four Colombian communities. Results: The surveys show knowledge of the vector, but little knowledge about diagnosis, prognosis, and treatment. Vector infestation indices show Brazil to have good relative control, while Colombia presents a high transmission risk. Conclusions: Given the multidimensionality of dengue control, vertical control strategies are inadequate because they deny contextualized methods, alternative solutions, and local empowerment.
Mostrar mais

5 Ler mais

Respiratory Health - Exposure Measurements and Modeling in the Fragrance and Flavour Industry.

Respiratory Health - Exposure Measurements and Modeling in the Fragrance and Flavour Industry.

The model proposed by MANE can provide an operator exposure assessment during the use of a chemical identified as hazardous by inhalation or a preparation containing this kind of substance. It is based on the operating principle of the ECETOC-TRA model in which the modelled exposure is a function of the vapor pressure of the substance and is modulated by correction coefficients. Our methodology was, in a first step, to optimize the correlation between vapor pressure and initial exposure; and in a second step to apply correction coeffi- cients, to more accurately take into consideration the real parameters of the different working places, as detailed hereafter.
Mostrar mais

16 Ler mais

International program on chemical safety

International program on chemical safety

The purpose is to develop a Regional Program of Chemical Safety (RPCS) that will help generate and strengthen country programs for the identification, evaluation, prevention and control [r]

46 Ler mais

Show all 10000 documents...