Novas tecnologias para o controle da giberela do trigo na safra 2014 no sudoeste do Paraná

The work consists in wheat production system and the evolution of damage caused by wheat scab. The study considers the lack of resistant cultivars to the disease, the low efficiency of chemical control and the presence of mycotoxins in grains. The study aimed to confirm the effectiveness of fungicides prothioconazole and metconazole; prove the bar deposition efficiency with nozzles directed jets the side of the ear resulting in full coverage of trapped anthers; prove the viability of using a warning system (application after the start of flowering before the onset of rains provided for future 24-48 hours and try to improve the efficiency in controlling scab. The experiment was conducted in the experimental field of Technological University Federal do Paraná in the city of Pato Branco, Paraná, conducted in two seasons, the first established on May 6, 2014 and the second on 21 May 2014. It was used to cultivate Amethyst field of OR Improvement seeds, . Passo Fundo, Rio Grande do Sul Treatments consisted of a control without fungicide application and one and two applications of prothioconazole + 17.5% trifloxystrobin (Fox) 500 ml / ha; metconazole 8.0% + pyraclostrobin 13% ( Opera Ultra) 750 mL / ha In the evaluation, second season, metconazole + pyraclostrobin with two application statistically was the treatment that showed a lower incidence in spikes reducing from 100 to 63.3%;. metconazole + pyraclostrobin performed better also in reducing the incidence of spikelets, 80.3% to 34.7%; the control ears had better results in the second season with two applications of metconazole + pyraclostrobin; in spikelets, in his first season, metconazole + pyraclostrobin with two application resulted in better control with 67%; with two applications of metconazole + pyraclostrobin gave the highest yield even under climatic conditions favorable to disease; metconazole + pyraclostrobin in both seasons showed superior efficiency in controlling FHB giving greater weight gain; with two application of both fungicides, the hectoliter weight was 81 and 79, respectively, each fungicide; the application of fungicides was made in advance of expected rain, occurring seven days of rain and a total volume of 85,2mm the first time, and 16 days of rain and an accumulation of 400 mm in the second period; the test efficiency can be confirmed when the direction of the spray jets launched wings coupled in double nozzle bodies perpendicular to the target upright reaches the sides of the spike. The metconazole + pyraclostrobin proved the most effective fungicide against the prothioconazole + trifloxystrobin in wheat scab control in the 2014 harvest.

Destino no ambiente e comportamento agronômico de atrazina em resposta a doses e níveis de palha de espécies de cobertura de solo

The use of cover crops is a fundamental strategy to the weed management in Southern Brazil. In highly infested areas, the herbicides use is increasing, which increases the costs of the crops production as well as the environmental contamination. Oat and velvet bean plants havecontrasting characteristics regarding to residues decomposition speed and the capacity to immobilize Nitrogen in the soil, providing distinct results of weeds suppression throughout the time, and therefore, requiring distinct management strategies before, during, and after the corn crop establishment. The general objective of the experiment was to evaluate the environmental dynamics of the herbicide atrazine, the corn grain yield, and the efficiency of the weed control, considering areas with distinct history regarding the use of mulching, levels of straw and rates of atrazine. For this, the experiment was carried out in two parts: in the first part, two trials with the corn crop were established, one using oat and the other using velvet bean as cover crops. The experimental design used for both field trials was randomized complete blocks arrangement with four replications. The factor A was constituted by four levels of straw (0; 0.75x; 1.5x; 3x) and the factor B was constituted by four rates of the herbicide atrazine (0; 2100; 4200; 8400 g a i. ha-1). Soil samples were collected for greenhouse trialsto determine the persistence. Atrazine leaching evaluation was performed by chromatography using samples collected over the soil profile.In the field, the weed density, the fresh and dry weight and the yield of the corn were evaluated. In the greenhouse trials, the main variables evaluated were plant height and injury caused by the herbicide toxicity. In the second part, soils with distinct covering history were sampled, and the mineralization and sorption studies, both with 14C-atrazine, were conducted in the laboratory. The experimental design was randomized complete blocks arrangement with four replications. The results from the field experiment show that the high levels of straw above ground, isolated, were not efficient to control completely the weeds, and that high levels of velvet bean`s straw decreased the corn potential yield. The greenhouse trials showed that high levels of oat straw prevent the scape of atrazine to soil, this effect of oat straw upon the herbicide availability on soil was detected up to 12 days after spraying. The half-life of atrazine sprayed over oat straw varied from 7 to 14 days after spraying, while the half-life of atrazine sprayed over velvet bean varied from 5 to 14 days after spraying. Increasing oat straw levels presents the capacity to reduce the lixiviation of atrazine in the soil profile, however, this effect was not verified when using velvet bean straw, because the herbicide was not detected in the soil profile, at 21 days after spraying. The chromatographic analysis indicate thatthe atrazine concentrates closer to the soil surface regardless of amount of straw, not being detected deeper than 8 cm in the soil. The accumulated mineralization of 14C-arazine sprayed over V. sativa is superior if compared to soils with S. cereale or non-covered soils. The sorption coefficient of atrazine is superior when sprayed over straw than over the soil.