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

This study aimed to control different populations of Digitaria insularis by glyphosate herbicide, isolated and mixed, besides the combination of methods (chemical and mechanical) to manage resistant adult plants. Three experiments were conducted, one in pots which were maintained under non-controlled conditions and two under field conditions. In the experiment in pots, twelve populations of D. insularis were sprayed with isolated glyphosate (1.44 and 2.16 kg a.e. ha(-1)) and mixed (1.44 and 2.16 kg a.e. ha(-1)) with quizalofop-p tefuryl (0.12 kg i.a. ha(-1)). The treatment of 1.44 kg a.e. ha(-1) of glyphosate plus 0.12 kg a.i. ha(-1) of quizalofop was sufficient for adequate control (>95%) of all populations. Population 11 (area of grain production in Itumbiara, GO) was considered sensitive to glyphosate. Others populations were moderately sensitive or tolerant to the herbicide. In the field, the plants of D. insularis of one of the experiments were mowed and, in the other, there were not. Eight treatments with herbicides [isolated glyphosate (1.44 and 2.16 kg a.e. ha(-1)) and mixed (1.44 and 2.16 kg a.e. ha(-1)) with quizalofop-p-tefuryl at 0.12 kg a.i. ha(-1)), clethodim at 0.108 kg a.i. ha(-1)) or nicosulfuron at 0.06 kg a.i. ha(-1))] were assessed, in combination with or without sequential application of the standard treatment, sprayed 15 days after the first application. The combination of the mechanic control with the application of glyphosate (2.16 and 1.44 kg a.e. ha(-1)) plus quizalofop-p-tefuryl (0.12 kg a.i. ha(-1)) or clethodim (0.108 kg a.i. ha(-1)), associated to the sequential application, was the most effective strategy for the management of adult plants of resistant D. insularis.

Plant density in production of mini lettuce cultivars in organic system management

Production of mini vegetables in organic system is a good alternative to improve profit, but there are no researches about the optimum plant density for these cultivars in Brazilian conditions. Two experiments were conducted to evaluate the production of mini lettuce cultivars in different plant densities. Experiment 1 was conducted from January 1th (sowing) to February 10th (harvesting), 2012. The experimental design was completely randomized blocks, with six treatments in factorial scheme, 3 mini lettuce cultivars (Tudela, Renoir and Sartre) x 2 spacing between plants (16 and 20 cm), with eight replications and plots (2.04 m(2)) with six rows, spaced 15 cm. Experiment 2 was conducted from June 6th (sowing) to July 18th (harvesting), 2012. The cultivars Sartre and Renoir were evaluated under four plant densities (444,444; 333,333; 266,667 and 200,000 plants ha(-1), corresponding to spacing of 15x15, 15x20, 25x15 and 25x20 cm, respectively). Eight treatments were defined by a factorial scheme 2 (cultivars) x 4 (plant densities) and arranged in a completely randomized block design, with nine replications and plots with 2.04 m2. The evaluated characteristics in both experiments were total and marketable fresh weight per plant, plant dry weight, plant diameter and height, marketable yield and discard percentage. In first experiment, during the summer, cultivar Sartre showed the highest marketable fresh weight (72 g plant(-1)). Heaviest plants (91.6 g plant(-1)) were obtained with the higher plant spacing, but the highest yield (2.51 kg m(-2)) was obtained with the smaller spacing. In winter, plants with higher total (190 g plant(-1)) and marketable (146 g planta(-1)) fresh weight were obtained with cultivar Sartre, and the same was observed in low plant density. However, the higher plant density, the higher the yield.

Use of grass carp (ctenopharyngodon idella) as a biological control agent for submerged aquatic macrophytes

This study aimed to evaluate feed preference and control efficacy of grass carp (Ctenopharyngodon idella) on the aquatic macrophytes Ceratophyllum demersum, Egeria densa and Egeria najas. An experiment was carried out at mesocosms conditions with 2,000 liters capacity and water residence time of 2.8 days. C. demersum, E. densa e E. najas biomasses were offered individually with sixty g and coupled in similar quantities of 30 g of each species, evaluated during 81 days, envolving 6 treatments. (1 - C. demersum, 2 - E. najas, 3 - E. densa, 4 - C. demersum + E. najas, 5 - C. demersum + E. densa and 6 - E. najas + E. densa). When offered individually, E. najas and C. demersum presented the same predation rate by grass carp, which was higher than E. densa predation rate. When plants were tested in pairs, the order of feed preference was C. demersum > E. najas > E. densa. E. najas and C. demersum percentage control ranged from 73 to 83%. No relation between biomass consumption and grass carp body weight gain was observed, probably due to differences in nutritional quality among macrophyte species according to fish necessities. Therefore, it is concluded that the use of grass carp is one excellent technique to control submersed macrophytes in Brazil.

Biochemical changes during the induction of mineral stress in plants of bell pepper cultivated in fertigation system

The greenhouse production associated with the fertigation management, have established in Brazil as economical alternative for several horticultural species. With this strategy this study had as aim to evaluate possible impacts in the metabolism of plants of bell pepper (Capsicum annuum L.; cv Elisa) in response to the increase of mineral concentration in the soil. During the experiments, the some nutrient concentrations were altered, to obtain high values of electric conductivity (EC) in the soil solution. The EC values commonly observed in the traditional fertigation system were adopted, as control. It was also verified the possibility of reduction of the mineral stress impact by the application of organic matter in the soil. Parameters of the antioxidative response system, as the superoxide dismutase (SOD) and catalase enzyme activities besides the proline content were evaluated to measure the extension of the saline stress and their effects on the plants. The increase of EC of the soil induced to the increase of the proline concentration and the SOD activity. Unexpectedly, it was verified that the saline stress inhibited the activity of the enzyme catalase. It was also concluded that the monitoring of EC of the soil is an indispensable tool to reach success in the fertigation system and that the study of the activity of the enzymes of the antioxidative response system, and the proline contents can be assumed as indicators in of the levels of stress in bell pepper plants (Capsicum annuum L.; cv Elisa).

Carbohydrates, growth and production of -roxo de valinhos- fig tree in initial development under irrigation management

The carbohydrates translocation and consequently growth and production of fig tree (Ficuscarica L.) vary according to the different management on cultivation conditions. The aim of this study was to evaluate the changes in the levels and total carbohydrates accumulation together with growth and “Roxo de Valinhos” fig trees production onimplementation of orchards in initial phase, cultivated with and without irrigation. We adopted a factorial arrangement (2 x 7) with four repetitions distributed in installments (with and without irrigation) subdivided in time (collect time). Destructive analyzes were performed at 40, 80, 120, 160, 200, 240 and 280 days after pruning (DAP) and are measured: stem diameter and branch, stem length and branch, number of leaves, internodes and fruit. Subsequently, the plant parts were sectioned to obtain the leaf area, length and roots volume, fresh and dry matter weight. The number, weight and total productivity of fruits were evaluated. The media of all growth attributes and production characteristics were higher in treatments with water irrigation. The total carbohydrate content was higher at 120 and 160 DAP and the carbohydrates accumulation was increasing for most institutions over the plants development, except for the leaves that showed a decrease in the levels at 160 DAP. The fruits showed greater carbohydrates accumulation in relation to the other evaluated organs.

Pruning management of cassava for animal feeding: parameters of the root

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da competitividade e da inserção em redes sociais dos piscicultores da UHE Canoas I

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da competitividade e da inserção em redes sociais dos piscicultores da uhe canoas I

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da competitividade e da inserção em redes sociais dos piscicultores da UHE Canoas I

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Crop, Native Vegetation, and Biofuels: Response of White- Tailed Deer to Changing Management Priorities

The expansion of the cellulosic biofuels industry throughout the United States has broad-scale implications for wildlife management on public and private lands. Knowledge is limited on the effects of reverting agriculture to native grass, and vice versa, on size of home range and habitat use of white-tailed deer (Odocoileus virginianus). We followed 68 radio-collared female deer from 1991 through 2004 that were residents of DeSoto National Wildlife Refuge (DNWR) in eastern Nebraska, USA. The refuge was undergoing conversion of vegetation out of row-crop agriculture and into native grass, forest, and emergent aquatic vegetation. Habitat in DNWR consisted of 30% crop in 1991 but removing crops to establish native grass and wetland habitat at DNWR resulted in a 44% reduction in crops by 2004. A decrease in the amount of crops on DNWR contributed to a decline in mean size of annual home range from 400 ha in 1991 to 200 ha in 2005 but percentage of crops in home ranges increased from 21% to 29%. Mean overlap for individuals was 77% between consecutive annual home ranges across 8 years, regardless of crop availability. Conversion of crop to native habitat will not likely result in home range abandonment but may impact disease transmission by increasing rates of contact between deer social groups that occupy adjacent areas. Future research on condition indices or changes in population parameters (e.g., recruitment) could be incorporated into the study design to assess impacts of habitat conversion for biofuel production.

Effectiveness of Milorganite® as a Repellent to Protect Ornamental and Agronomic Plants From Deer Over-Browsing

When deer populations become locally overabundant, browsing of ornamental and agronomic plants negatively affects plant establishment, survival, and productivity. Milorganite® is a slow-release, organic fertilizer produced from human sewage. We tested Milorganite® as a deer repellent on chrysanthemums (Chrysanthemums morifolium) in an urban/suburban environment, and soybeans (Gycine max) in a rural agriculture environment. Six beds of chrysanthemums at two sites were monitored for 28 to 35 days. Treatment plants received a top dressing of 104 grams of Milorganite® (1120.9 kg/ha). Milorganite® treated plants had more (P < 0.001) terminal buds and achieved greater height (P < 0.002) compared to controls at one site, however damage observed was similar at the second site. In a second experiment, 0.2-ha plots of soybeans (Glycine max) were planted on five rural properties in northeastern Georgia and monitored for ≥ 30 days. Treated areas received 269 kg/ha of Milorganite®. In 4 of 5 sites, Milorganite® delayed browsing on treated plants from 1 week to > 5 weeks post-planting. Duration of the protection appeared to be related to the difference in deer density throughout most of the study areas. Results of this study indicate Milorganite® has potential use as a deer repellent.

Impacts of Plant Size, Density, Herbivory, and Desease on Native Platte Thistle (Cirsium Canescens)

Abstract. Based on prior field observations, we hypothesized that individual and interacting effects of plant size, density, insect herbivory, and especially fungal disease, influenced seedling and juvenile plant growth in native Platte thistle populations (Cirsium canescens Nutt.). We worked at Arapaho Prairie in the Nebraska Sandhills (May - August 2007), monitoring plant growth, insect damage, and fungal infection within different density thistle patches. In the main experiment, we sprayed half of test plants in different density patches with fungicide (Fungonil© Bonide, containing chlorothalonil) and half with a water control. Fungal infection rates were very low, so we found no difference in fungal attack between these treatments. However, plants that received the fungicide treatment had significantly faster growth over the season than did the control plants. At the same time, plants in the fungicide treatment had significantly reduced insect herbivory. These results strongly suggest that the fungicide had insecticidal effects and that insect herbivory significantly decreases juvenile Platte thistle growth. Further, damage by insect herbivores tended to be higher for larger plants, and herbivory was variable among different patches. However, plant density did not appear to have a large effect on the amount of insect herbivory that individual juvenile Platte thistle plants received. In the second experiment, we examined germination and survival success in relationship to seed density, and found that germination success was higher in areas of lower seed density. In the third experiment, we tested germination for filled seeds categorized primarily by color variation and size, and found no difference in germination related to either color or seed weight. We conclude that seed density, but not seed quality as estimated by color or size, affects germination success. Further, although herbivory was not significantly affected by plant density at any of the scales examined, insect herbivory significantly reduces the growth and success of juveniles of this characteristic native sand prairie plant.

G93-1167 Spider Mite Management in Corn and Soybeans

This NebGuide describes the two common spider mites found in Nebraska corn and soybeans, their natural enemies and management. Two species of spider mites, the Banks grass mite and twospotted spider mite, commonly feed on Nebraska corn. Banks grass mites (BGM) feed almost exclusively on grasses, including corn and sorghum. Twospotted spider mites (TSM) not only feed on many species of grasses, but also on soybeans, fruit trees and a variety of vegetables and ornamental plants. Although these two species are somewhat similar in appearance, they differ in several biological characteristics and in their susceptibility to pesticides. Banks grass mites usually appear earlier in the season, feed mostly on the lower leaves of the corn plant, and in Nebraska are moderately susceptible to many of the commonly used miticides. On the other hand, TSM tend to appear in mid to late season, increase rapidly, feed over the entire plant, and often are not consistently controlled by available pesticides.

Lethal effects of abamectin on the aquatic organisms Daphnia similis, Chironomus xanthus and Danio rerio

Abamectin is used as an acaricide and insecticide for fruits, vegetables and ornamental plants, as well as a parasiticide for animals. One of the major problems of applying pesticides to crops is the likelihood of contaminating aquatic ecosystems by drift or runoff. Therefore, toxicity tests in the laboratory are important tools to predict the effects of chemical substances in aquatic ecosystems. The aim of this study was to assess the potential hazards of abamectin to the freshwater biota and consequently the possible losses of ecological services in contaminated water bodies. For this purpose, we identified the toxicity of abamectin on daphnids, insects and fish. Abamectin was highly toxic, with an EC50 48 h for Daphnia similis of 5.1 ng L-1, LC50 96 h for Chironomus xanthus of 2.67 mu g L-1 and LC50 48 h for Danio rerio of 33 mu g L-1. (C) 2011 Elsevier Ltd. All rights reserved.

Glyphosate has low toxicity to citrus plants growing in the field

Gravena, R., Filho, R. V., Alves, P. L. C. A., Mazzafera, P. and Gravena, A. R. 2012. Glyphosate has low toxicity to citrus plants growing in the field. Can. J. Plant Sci. 92: 119-127. There has been controversy over whether glyphosate used for weed management in citrus fields causes significant toxicity to citrus plants. Glyphosate may be toxic to non-target plants exposed to accidental application or drift. This work evaluated glyphosate toxicity in plants of Valencia citrus (Citrus sinensis. L. Osbeck) grafted onto 'Rangpur lime' (Citrus limonia L. Osbeck) and citrumelo 'Swingle' (Poncirus trifoliata (L.) Raf x Citrus paradisi Mad) by trunk- or foliar-directed herbicide applications under field conditions. In the first experiment, glyphosate was sprayed at rates of 0, 90, 180, 260, 540, 1080 and 2160 g a.e. ha(-1) directly on the trunk to a height of 5 cm above the grafting region. In the second experiment, glyphosate was sprayed on the plant canopies at rates of 0, 0.036, 0.36, 3.6, 36, 360 and 720 g a.e. ha(-1). There was no visual damage caused by glyphosate applied directly to the trunk, but the plants were affected by glyphosate sprayed directly on the canopies at rates over 360 g a.e. ha(-1). The main symptom was observed in the new shoots formed after the application, indicating an effect on meristems. Little or no effect was observed in mature leaves. Eight days after application the levels of shikimate, total free amino acids and total phenolic compounds were unaffected. All plants affected by glyphosate recovered between 6 and 12 mo after the treatments. Therefore, despite some transient symptoms Valencia citrus grafted onto 'Rangpur lime' and citrumelo 'Swingle' were tolerant to glyphosate.