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Number of results: 4
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Abstract

The study of herbicide dynamics in the soil and their interaction with the components of the environment makes it possible to ensure the selectivity of crops and the agronomical efficiency. The aim of this research was to evaluate the influence of soil physicochemical properties on the emergence and growth of soybean, with pre-emergence application of various saflufenacil rates. An experiment was carried out in a greenhouse with a completely randomized design, testing different soil types containing “Erechim”, “Santa Maria” and “Eldorado do Sul”, at different saflufenacil rates: 0, 12.5, 25, 50, 100, 200, 400 g a.i. · ha–1. The application was performed 1 day after soybean sowing, and analyzed variables were: the phytotoxicity emergence of seedlings, dry mass and height of the soybean. The saflufenacil effective dose of 50% response in soybean (ED50) and the characteristics of the soils showed that the soil contained clay and sand which were the components most related to the saflufenacil availability to the plants. A lower ED50 by phytotoxicity to the soybean was found in soil with lower and greater content of clay and sand, respectively. The physicochemical properties of soil influenced the saflufenacil activity, having greater potential of injury to soybean in the soil from Eldorado do Sul, due to its clay and sand content.
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Authors and Affiliations

Geovana Facco Barbieri
1
Cassiano Salin Pigatto
1
Glauco Pacheco Leães
2
Nelson Diehl Kruse
2
Dirceu Agostinetto
1
André da Rosa Ulguim
2

  1. Plant Protection Department, Federal University of Pelotas, Av. Eliseu Maciel, 96160-000, Capão do Leão, Rio Grande do Sul, Brazil
  2. Plant Protection Department, Federal University of Santa Maria, Av. Roraima, 1000, 97105-900, Santa Maria, Rio Grande do Sul, Brazil
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Abstract

The tea plant [ Camellia sinensis (L.) O. Kuntze] is one of the most significant commercial crops in Iran. Symptomatic leaves including chlorina on the edge of the leaf, and multiple necrotic ring blotches on mature leaves from different tea gardens were observed in northern Iran. RT-PCR analysis and transmission electron microscopy observations were applied to characterize the causal agent of tea leaf discoloration. Sequence analyses of the fragments revealed that all the samples were infected with tea plant necrotic ring blotch virus (TPNRBV). To our knowledge this is the first report of TPNRBV in Iran and the second in the world.
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Authors and Affiliations

Eisa Nazerian
1
ORCID: ORCID
Hossein Bayat
2

  1. Department of Technology and Production Management, Tea Research Center, Horticultural Sciences Research Institute, Lahijan, Iran
  2. Department of Technology and Production Management Ornamental Plant Research Center, Horticultural Sciences Research Institute, Mahallat, Iran
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Abstract

The olive psyllid Euphyllura straminea Loginova (Hemiptera: Aphalaridae) is one of the most important pests of olive trees in Iran. To determine this pest’s economic injury level (EIL) and to evaluate the relationship between density of nymphs (DON) and yield loss, different densities of olive psyllid nymphs were maintained on olive trees by different insecticide concentrations. Counting nymphs on olive terminal shoots was done to determine nymph abundance at the end of nymphal stage. Different densities of olive psyllid nymphs resulted in significantly different yield losses of olive trees. Regression analysis was used to determine the relationship between nymph density and yield loss. Considering pest management costs, the market value of olive, and insecticide efficiency, economic injury levels were evaluated from 4.08 to 7.14 nymphal days. The olive psyllid EIL values could be used to plan a pest control program in Zanjan and Guilan provinces.
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Authors and Affiliations

Aref Marouf
1
Mohammadreza Abbasi Mojdehi
2
Shamsollah Najafi
1

  1. Plant Protection Department, Agricultural and Natural Resources Research Center of Zanjan Province (AREEO), Iran
  2. Plant Protection Department, Agricultural and Natural Resources Research Center of Guilan Province, Rasht, Iran
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Abstract

The high sensitivity of beans to herbicides is one of the limiting factors regarding the management of dicot weeds in bean crops. Protoporphyrinogen oxidase (PPO) inhibition is an important mechanism of action that has unregistered molecules with potential use in bean crops. The objectives of this study were to investigate the tolerance of Brazilian bean cultivars to distinct PPO inhibitors and to determine the existence of cross-tolerance in cultivars to the different PPO inhibitor chemical groups. In the first and second experiments, the BRSMG Talismã, Jalo Precoce, BRS Esplendor, and IPR 81 cultivars were subjected to saflufenacil doses pre- (0, 9.6, 14.1, 20.5, 30.0, and 43.8 g a.i. ‧ ha–1) and post-emergence (0, 0.7, 1.0, 1.5, 2.1, and 3.1 g a.i. ‧ ha–1). In the third experiment, the tolerance of 28 bean genotypes to saflufenacil (20.5 g a.i. ‧ ha–1) in pre-emergence was determined. In the fourth, fifth, sixth and seventh experiments, we investigated the cross-tolerance of bean to the fomesafen, flumioxazin, sulfentrazone, and saflufenacil herbicides, respectively. Even very low saflufenacil doses in post-emergence caused plants of all cultivars to die rapidly; therefore, the tolerance was much lower at this application time than in pre-emergence. There was high tolerance variability to saflufenacil among the 28 cultivars. The bean tolerance to fomesafen, flumioxazin, sulfentrazone, and saflufenacil applied pre-emergence depended on the cultivar and dose. Fomesafen was highlighted owing to its higher selectivity in relation to the different cultivars. No cross-tolerance pattern to the PPO inhibitor chemical groups applied in pre-emergence was observed among the evaluated bean cultivars. The results of this study could be of significance to farmers and technical assistance personnel, as well as for future research on cultivar breeding and the elucidation of biochemical and genetic mechanisms involved in herbicide tolerance.
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Authors and Affiliations

Antonio Pedro Brusamarello
1
Michelangelo Muzell Trezzi
1
Fortunato de Bortoli Pagnoncelli Júnior
1
Paulo Henrique de Oliveira
1
Taciane Finatto
1
Marcos Vinícius Jaeger Barancelli
1
Bruno Alcides Hammes Schmalz
1
Patrícia Bortolanza Pereira
1

  1. Department of Agronomy, Federal Technological University of Paraná (UTFPR), Brazil

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