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dos Santos S.R.,State University of Montes Claros | Kondo M.K.,State University of Montes Claros | de Oliveira P.M.,Agriculture and Livestock Research Enterprise of Minas Gerais EPAMIG | Junior I.O.A.,State University of Montes Claros | de Matos A.T.,Federal University of Vicosa
Australian Journal of Crop Science | Year: 2015

Irrigation with wastewater is an agricultural practice used to supply plants with nutrients that can reduce the nutrient load impact on fresh water sources and save conventional water sources. However, the physical and chemical properties of soil can be altered according to specific wastewater characteristics. This study aimed to investigate short-term changes in soil physical and chemical properties after irrigation of cotton with preliminary treated wastewater (PTW) and tertiary treated wastewater (TTW) as potassium sources in the semi-arid region of Minas Gerais State, Brazil. A randomized complete block design (RCBD) with four replications and five treatments was used: a combination of two wastewaters (PTW and TTW) as potassium topdressing sources and two equivalent doses to 40 and 60 kg K2O ha-1, as well as a control treatment with a conventional mineral fertilizer. After the first soil sampling, the liming, NPK fertilizer, urea and potassium chloride treatments increased the base saturation and electrical conductivity up to 0.4 m soil depth. Wastewater potassium sources did not promote chemical excesses in the four soil depths evaluated, although the sodium content increased up to 0.6 m depth with 60 kg K2O ha-1 via TTW. The same dose (60 kg K2O ha-1) via PTW decreased the soil pH in the top 0.2 m and the water-dispersible clay (WDC) level up to 0.6 m depth due to the better chemical balance of this wastewater. In general, it is recommended to use PTW when providing 60 kg K2O ha-1 in topdressing. Source

Evaristo A.B.,Federal University of Vicosa | Venzon M.,Agriculture and Livestock Research Enterprise of Minas Gerais EPAMIG | Matos F.S.,Federal University of Goais | de Freitas R.G.,Federal University of Vicosa | And 2 more authors.
Experimental and Applied Acarology | Year: 2013

The broad mite Polyphagotarsonemus latus is a key pest of physic nut (Jatropha curcas L.). The purpose of this study was to identify physic nut accessions that are less susceptible to P. latus, in support of the breeding program of J. curcas. We first evaluated population growth rate and injury symptoms of P. latus on different J. curcas accessions and then carried out physiological analyses on P. latus-infested and uninfested accessions. From the germplasm bank of the Federal University of Viçosa, 15 physic nut accessions with high seed oil content, with different genetic background, were tested. The following traits were evaluated: instantaneous population growth rate of P. latus (r i), injury symptoms, relative leaf water content, specific leaf area, gas exchange, photosynthetic pigments, nitrogen and biomass of the aerial part. Significant differences were observed for P. latus population growth rate and injury symptoms among accessions. A positive correlation between P. latus growth rate and injury was found. The UFVJC72 accession stood out as the more resistant, considering P. latus growth rate and injury symptoms, compared with most accessions. Physiological responses did not vary among accessions, but did between infested and uninfested plants. In P. latus-infested plants, net photosynthesis was on average 50.5 % lower than in uninfested plants, whereas stomatal conductance and transpiration decreased by 46.2 and 51.6 %, respectively. © 2013 Springer Science+Business Media Dordrecht. Source

Marques R.V.,Federal University of Tocantins | Sarmento R.A.,Federal University of Tocantins | Ferreira V.A.,Federal University of Vicosa | Venzon M.,Agriculture and Livestock Research Enterprise of Minas Gerais EPAMIG | And 4 more authors.
Revista Colombiana de Entomologia | Year: 2014

In Brazil, smallholders produce the physic nut Jatropha curcas in association with crops such as pumpkin and corn, besides weeds. We evaluated the suitability of pumpkin and corn pollens, as well as pollen from a weed species (Peltaea riedelii), present in physic nut crop, as alternative food to predatory mites Euseius concordis and Iphiseiodes zuluagai. These species are natural enemies of Polyphagotarsonemus latus and Tetranychus bastosi, two important mite pests on J. curcas plants. The survival and oviposition rate of E. concordis and I. zuluagai were evaluated for five days on leaf discs supplied with pollen of pumpkin, corn or P. riedelii. Castor bean pollen (Ricinus communis) was provided to the predators as a control of suitable food. No significant difference on the oviposition rate of both I. zuluagai and E. concordis was observed when they fed with pollen from the three plants. However, the source of pollen affected the survival of the predatory mites. Pumpkin pollen was the worst food for both predatory mites while corn and P. riedelii was a better food. These results indicate the non-suitability of pumpkin pollen as alternative food to I. zuluagai and E. concordis. Corn and P. riedelli are sources of supplementary food to the predatory mites and can sustain predator populations when prey is scarce. © 2014 The American Society for Cell Biology. Source

Tuelher E.S.,Federal University of Vicosa | Venzon M.,Agriculture and Livestock Research Enterprise of Minas Gerais EPAMIG | Guedes R.N.C.,Federal University of Vicosa | Pallini A.,Federal University of Vicosa
Crop Protection | Year: 2014

Organic coffee growers in Brazil often spray a wide range of organic-farming compatible products to control pests including the southern red mite, Oligonychus ilicis. However, most of these products have not yet been proven to be effective for mite control and there is no information about their side effects on natural enemies. We evaluated the lethal and sublethal effects of three organic compatible products, the biofertilizer Supermagro, a fresh bovine manure supplemented with micronutrients, bone meal, unrefined sugar, and milk to stimulate fermentation, an enriched Bordeaux mixture (Viça Café Plus®) and lime sulfur to O.ilicis and to its predatory mite Iphiseiodes zuluagai. Additionally, we evaluated the efficacy of these products against O.ilicis under greenhouse conditions. Only lime sulfur showed acute lethal effects at concentrations lower than the field recommended rates (20-40ml/l). The predatory mite I.zuluagai was more tolerant than its prey to the three products based on acute lethal concentration bioassays. The instantaneous rate of increase (ri) of O.ilicis when exposed to lime sulfur at field recommended rates was negative but ri of the predatory mite, I.zuluagai was not. The ri of the predatory mite was lower than that of its prey under Supermagro and Viça Café exposure, including at their field recommended rates (200ml/l and 10g/l, respectively). In a greenhouse experiment, the control efficacy against O.ilicis 14 days after spraying reached levels higher than 80% for all three products. Lime sulfur has the potential to control O.ilicis in organic coffee plantations. Although, Supermagro and Viça Café exhibited potential to control O.ilicis in the greenhouse, the product concentrations used were very high and may lead to selectivity problems. Therefore, spraying suitable concentrations of such products taking into account their effectiveness against O.ilicis and their selectivity to natural enemies are important for ecological pest management in organic coffee besides benefiting coffee plant nutrition. 22;Supermagro and Viça Café were effective only at high concentrations. © 2013 Elsevier Ltd. Source

Venzon M.,Agriculture and Livestock Research Enterprise of Minas Gerais EPAMIG | Oliveira R.M.,Federal University of Vicosa | Perez A.L.,Federal University of Vicosa | Rodriguez-Cruz F.A.,Federal University of Vicosa | Martins Filho S.,Federal University of Vicosa
Pest Management Science | Year: 2013

Background: An acaricidal effect of lime sulfur has not been demonstrated for Polyphagotarsonemus latus. However, lime sulfur can cause toxicity to natural enemies and to host plants. In this study, the toxicity of different concentrations of lime sulfur to P. latus, to the predatory mite Amblyseius herbicolus and to the predatory insect Chrysoperla externa was evaluated. Additionally, the phytotoxicity of lime sulfur to two P. latus hosts, chili pepper and physic nut plants, was determined. Results: Lime sulfur at a concentration of 9.5 mL L-1 restrained P. latus population growth. However, this concentration was deleterious to natural enemies. The predatory mite A. herbicolus showed a negative value of instantaneous growth rate, and only 50% of the tested larvae of C. externa reached adulthood when exposed to 10 mL L-1. Physic nut had severe injury symptoms when sprayed with all tested lime sulfur concentrations. For chili pepper plants, no phytoxicity was observed at any tested concentration. Conclusion: Lime sulfur might be used for P. latus control on chili pepper but not on physic nut owing to phytotoxicity. Care should be taken when using lime sulfur in view of negative effects on natural enemies. Selective lime sulfur concentration integrated with other management tactics may provide an effective and sustainable P. latus control on chili pepper. © 2012 Society of Chemical Industry. Source

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