Giuvan Lenz

Equipamentos de pulverização aérea e taxas de aplicação de fungicida na cultura do arroz irrigado

O controle eficiente de doencas na cultura do arroz irrigado depende da selecao correta do equipamento, da taxa de aplicacao e da indicacao certa do produto quimico. O objetivo deste trabalho foi verificar a deposicao de gotas na cultura do arroz comparando-se bicos hidraulicos no sistema convencional, eletrostatico e atomizador rotativo de disco, em diferentes taxas de aplicacao por via aerea; para tanto, foram estudadas a densidade e a penetracao de gotas nos estratos medio e inferior, produtividade e rendimento de engenho do arroz. Os tratamentos avaliados foram: bico hidraulico 20 e 30 L ha-1, eletrostatico 5 e 10 L ha-1 e atomizador rotativo de disco 6, 10 e 15 L ha-1. Nao foram verificadas diferencas de produtividade e os equipamentos bico hidraulico 20 L ha-1 e atomizador rotativo de disco 15 L ha-1 proporcionaram maior rendimento de engenho. Maiores taxas de aplicacao usando-se bicos hidraulicos e atomizador rotativo proporcionaram maior penetracao e, consequentemente, tambem maior densidade de gotas nos dois estratos avaliados.

Elaboração e validação de escala diagramática para quantificação da mancha de isariopsis da videira

The lack of a standardized visual method may lead to inaccurate severity estimative and wrong conclusions. The objective of this research was to develop a diagrammatic scale to assess the severity of grape isariopsis leaf spot on grape, caused by Isariopsis clavispora. A diagrammatic scale with six levels of disease severity (1.60; 3.20; 6.60; 13.00; 24.10 e 40.24%) was developed and validated to assess grape isariopsis leaf spot. For validation, the severity of 30 leaves presenting different intensities of the disease was estimated by eight raters. Accuracy and precision were determined by linear regression and by the actual severity scale. This one provided good levels of accuracy and accuracy of visual estimation. The coefficient determination average was higher than 0.89, and absolute errors were lower than acceptable limits. The levels of accuracy, precision and reproducibility measurements of isariopsis leaf spot severity on grape significantly improved with the use of diagrammatic scale. The proposed diagrammatic scale proved to be adequate for severity assessments of grape isariopsis leaf spot.

Reaction of commercial germplasm of soybean to Colletotrichum truncatum

During the period between March, 2004 and January 2005, the reaction of 48 commercial cultivars of soybean to Colletotrichum truncatum was evaluated in the greenhouse facilities of the Universidade Federal de Santa Maria. The seedlings were inoculated in the stadium V1/V2 . After inoculation, plants were kept in the greenhouse under a relative humidity of 95% for 10 days, before evaluation. After that period, the seedlings were evaluated to determine the reaction of cultivars. Seedlings were evaluated for disease reaction according to a scale with values from 1 to 9. Only the cultivars Tabarana, Cometa and Emgopa 316 showed to be susceptible to Colletotrichum truncatum.

Reação de germoplasma crioulo de feijoeiro (Phaseolus vulgaris L.) a Colletotrichum lindemuthianum

Sixty genotypes of common bean (Phaseolus vulgaris) from the Meso-American and Andean gene pool were evaluated in 2003 and 2004 at Universidade Federal de Santa Maria, State of Rio Grande do Sul, Brazil. Host genetic structure was evaluated based on the reaction of the sixty genotypes, in the juvenile state (V1/V2) to 12 physiological races of Colletotrichum lindemuthianum. The phenetic analysis was generated from virulence data considering incompatible and compatible reactions. Lower resistance index was observed. However, complex resistance was found in some genotypes. Higher genetic variability for resistance to Colletotrichum lindemuthianum was observed in the Andean than the Meso-American germplasm.

Aplicação aérea de fungicidas na cultura do arroz irrigado com diferentes bicos de pulverização

In the harvest year of 2007/2008 a study was carried to evaluate the droplets deposition and penetration throughout water sensible cards and gas chromatographic analysis. Were used the hydraulic nozzle, electrostatic nozzle and rotary-disk atomizer spraying systems, with different volumes of spray solution. Aerial applications were performed at R3 stage using the aircraft Ipanema EMB-202 and the fungicide trifloxystrobin + propiconazole. Throughout the lection of the water sensible cards was determinate the droplet density, the medium numeric diameter, the medium volumetric diameter, the relative amplitude and the percentage of droplet penetration in the canopy. Chromatographic analysis was also performed to determinate the fungicide penetration into the biological target. The pulverization systems hydraulic nozzle 20L ha-1 and 30L ha-1 and the electrostatic system 10L ha-1 demonstrated higher droplet density in the upper third. The rotary-disk atomizer 15L ha-1 showed higher droplet density in the mid and low third. To the medium volumetric diameter, the electrostatic nozzles and the rotary-disk atomizer showed the lowest values. The higher homogeneity in the upper third was attained with rotary-disk atomizer at the pulverization rates of 6L ha-1 and 10L ha-1. The chromatographic analysis showed that the higher quantity of product retention was obtained with the electrostatic system at the pulverization rate of 10L ha-1 in the lower plant extract.

Severidade de doenças e manutenção da área foliar verde em função da aplicação de micronutrientes e fungicidas em trigo

In the crop cycle of 2007, an experiment was carried out in order to evaluate the influence of zinc, manganese and molybdenum sprayed together with fungicides on the severity of diseases and leaf area maintenance in wheat. Fungicides were sprayed at the end of booting and during flowering, whereas micronutrients were only sprayed during flowering. Micronutrients levels in the leaves, severity of diseases caused by Drechslera tritici and Septoria tritici, SPAD (Soil Plant Analysis Development) index, hectoliter weight, thousand-grain weight, ear size, and grain yield were evaluated. The use of epoxiconazol + pyraclostrobin led to a better control of Drechslera tritici and Septoria tritici. Products containing epoxiconazol + pyraclostrobin had an effect on plant physiology by increasing the levels of micronutrients in tissues and prolonging the time during which wheat remained with photosynthetically active leaf area. Epoxiconazol + pyraclostrobin, pyraclostrobin and epoxiconazol sprayed in association or not with micronutrients, led to increased hectoliter weight, thousand-grain weight and grain yield relative to control.

Caracterização da pulverização de fungicida na cultura do trigo com pontas hidráulicas e atomizadores rotativos de discos

The study aimed to evaluate the pulverization characteristics of the hydraulic nozzles and rotary-disk atomizer with different spraying rates on wheat crops, and their operational capacity. For this reason were installed two experiments, on the harvest years of 2009 and 2010. In first year was used the cultivar Fundacep 30, and in the second year the cultivars Pampeano and Nova Era. The experiments evaluating the pulverization with flat nozzles and hollow cone spray nozzle, both with the pulverization rate of 120 L ha-1, and rotary-disk atomizer with 24 and 34 L ha-1 in low volume in oil. The evaluated parameters were the droplet density and the medium volumetric diameter on the upper, mid and lower third throughout the analysis of water sensible cards. Also, was calculated the operational capacity of the traits. The results showed that the rotary-disk atomizer with 24L ha-¹ showed a higher droplet density on the upper third, however, there was no difference among the mid and lower thirds treatments. The rotary-disk atomizer presented droplets of smaller medium volumetric diameter compared to the hydraulic nozzles that presented high droplet heterogeneity. The higher operational capacity was achieved with the atomizers, due the lower spray volume used by this equipment.

Tilletia barclayana: biologia e manejo em arroz irrigado

The rice kernel smut (Tilletia barclayana), which is considered as a secondary disease, lately has been growing in importance due to its high infestation levels and effects in seed yield. This disease is favored by elevated air temperatures and humidity; high nitrogen fertilizer rates a late sowing. In order to control it, the use or resistant varieties, appropriate sowing dates and balanced fertilization of the soil, are recommended practices.