Com o objetivo de avaliar o efeito da cobertura morta, produzida pelos adubos verdes lab-lab (Dolichos lablab L.), guandu-anão (Cajanus cajan (L.) Millsp), crotálaria (Crotalaria juncea L.), guandu (Cajanus cajan (L.) Millsp), milheto (Pennisetum glaucum (L.) Leeke), uma mistura de três coberturas (D. lablab + C. cajan + C. juncea), e a infestação natural do pomar de laranja, composta principalmente por capim-colonião (Panicum maximum Jacq.), sobre as plantas daninhas, bem como avaliar o efeito destas coberturas sobre as seguintes plantas daninhas: poaia (Richardia brasiliensis Gomes.), capim-colonião, erva-palha (Blainvillea biaristata DC.), falsa-serralha (Emilia sonchifolia (L.) DC.), capim-colchão (Digitaria horizontalis (Retz.) Koel.), corda-de-viola (Ipomea grandifolia (Dammer.) O’Donell), picão-preto (Bidens pilosa L.), guanxuma (Sida santaremnensis H. Monteiro.) e tiririca (Cyperus rotundus (L.) Pers.), em condições de pós e pré-emergência, foram instalados dois experimentos em condições de campo e quatro em condições de casa de vegetação, na Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Departamento de Produção Vegetal, Piracicaba, S.P. O delineamento experimental foi de blocos casualizados para um experimento em campo e blocos casualizados no esquema fatorial para os demais. O manejo mecânico das diferentes vegetações, foi realizado mediante a utilização de roçadeira lateral, marca KAMAQ, modelo NINJA MAC 260 que esta desenhada para projetar o material verde cortado, sobre a projeção da copa da árvore cítrica, formando dessa maneira uma camada de cobertura morta. Os parâmetros avaliados durante a condução dos experimentos, foram os seguintes: avaliações de contagem da infestação de plantas daninhas por vaso e ou por m2 (densidade), determinações de algumas propriedades químicas do solo e avaliações de produção de biomassa das plantas daninhas. Pelos dados obtidos nas condições locais dos experimentos conduzidos pode-se observar que: a utilização de coberturas mortas produzidas pelas distintas vegetações contribui, significativamente, na redução das populações das plantas daninhas, sendo os melhores resultados obtidos com a vegetação natural e a mistura dos adubos verdes; e que a adubação em área total, independentemente da cobertura vegetal utilizada apresenta uma menor densidade de plantas daninhas nas linhas das plantas cítricas. Sendo assim pode se concluir que a utilização de adubos verdes pode contribuir de maneira significativa na redução da comunidade infestante, auxiliando de forma sustentável o manejo integrado de plantas daninhas; além de contribuir com outros benefícios inerentes a utilização dessa prática. / With the objective of evaluating the effect of the mulches produced by the cover crop Dolichos lablab, Cajanus cajan, Crotalaria juncea, Pennisetum glaucum, a mixture of three cover crops (Dolichos lablab + Cajanus cajan + Crotalaria juncea), and a natural infestation in orange tree plantations composed mostly by Panicum maximum on weeds and to evaluate the effect of these cover crop on the following weeds Richardia brasiliensis, Panicum maximum, Blainvillea biaristata, Emilia sonchifolia, Digitaria horizontalis, Ipomea grandifolia, Bidens pilosa, Sida santaremnensis and Cyperus rotundus, in conditions of pos and pre-emergence, two experiments in field conditions and four in greenhouse conditions were carried out at the Superior School of Agricultura "Luiz of Queiroz", University of São Paulo, Plant Production Department, São Paulo, Piracicaba - SP - Brazil. The experimental design used was of randomized blocks for an experiment in the field and randomized blocks in the factorial design for the others. The mechanical management of the different crops was carried out utilizing a KAMAQ lateral rotary mower Ninja Mac 260, designed to throw the cut crops down forming a layer of mulch around the citric plant. The data collected during the experiments were planta/m2 and plant/pot density, determination of some chemical conditions of the soil and weed dry biomass production in g/pot. In the carried out experiments, it could be observed that the use of mulches produced by different crops contributes significantly to reduce weeds. The best results were obtained in a natural infestation and the mixture of three cover crops. The fertilization in the whole area regardless the cover crops, presents a minor density of weeds in the lines of the citric plants. Furthermore, it can be concluded that the use of cover crops contributes widely to reduce weeds, supporting integrated management of weeds and providing with other inherent benefits.

Com o objetivo de avaliar o efeito da cobertura morta, produzida pelos adubos verdes lab-lab (Dolichos lablab L.), guandu-anão (Cajanus cajan (L.) Millsp), crotálaria (Crotalaria juncea L.), guandu (Cajanus cajan (L.) Millsp), milheto (Pennisetum glaucum (L.) Leeke), uma mistura de três coberturas (D. lablab + C. cajan + C. juncea), e a infestação natural do pomar de laranja, composta principalmente por capim-colonião (Panicum maximum Jacq.), sobre as plantas daninhas, bem como avaliar o efeito destas coberturas sobre as seguintes plantas daninhas: poaia (Richardia brasiliensis Gomes.), capim-colonião, erva-palha (Blainvillea biaristata DC.), falsa-serralha (Emilia sonchifolia (L.) DC.), capim-colchão (Digitaria horizontalis (Retz.) Koel.), corda-de-viola (Ipomea grandifolia (Dammer.) O’Donell), picão-preto (Bidens pilosa L.), guanxuma (Sida santaremnensis H. Monteiro.) e tiririca (Cyperus rotundus (L.) Pers.), em condições de pós e pré-emergência, foram instalados dois experimentos em condições de campo e quatro em condições de casa de vegetação, na Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Departamento de Produção Vegetal, Piracicaba, S.P. O delineamento experimental foi de blocos casualizados para um experimento em campo e blocos casualizados no esquema fatorial para os demais. O manejo mecânico das diferentes vegetações, foi realizado mediante a utilização de roçadeira lateral, marca KAMAQ, modelo NINJA MAC 260 que esta desenhada para projetar o material verde cortado, sobre a projeção da copa da árvore cítrica, formando dessa maneira uma camada de cobertura morta. Os parâmetros avaliados durante a condução dos experimentos, foram os seguintes: avaliações de contagem da infestação de plantas daninhas por vaso e ou por m2 (densidade), determinações de algumas propriedades químicas do solo e avaliações de produção de biomassa das plantas daninhas. Pelos dados obtidos nas condições locais dos experimentos conduzidos pode-se observar que: a utilização de coberturas mortas produzidas pelas distintas vegetações contribui, significativamente, na redução das populações das plantas daninhas, sendo os melhores resultados obtidos com a vegetação natural e a mistura dos adubos verdes; e que a adubação em área total, independentemente da cobertura vegetal utilizada apresenta uma menor densidade de plantas daninhas nas linhas das plantas cítricas. Sendo assim pode se concluir que a utilização de adubos verdes pode contribuir de maneira significativa na redução da comunidade infestante, auxiliando de forma sustentável o manejo integrado de plantas daninhas; além de contribuir com outros benefícios inerentes a utilização dessa prática. / With the objective of evaluating the effect of the mulches produced by the cover crop Dolichos lablab, Cajanus cajan, Crotalaria juncea, Pennisetum glaucum, a mixture of three cover crops (Dolichos lablab + Cajanus cajan + Crotalaria juncea), and a natural infestation in orange tree plantations composed mostly by Panicum maximum on weeds and to evaluate the effect of these cover crop on the following weeds Richardia brasiliensis, Panicum maximum, Blainvillea biaristata, Emilia sonchifolia, Digitaria horizontalis, Ipomea grandifolia, Bidens pilosa, Sida santaremnensis and Cyperus rotundus, in conditions of pos and pre-emergence, two experiments in field conditions and four in greenhouse conditions were carried out at the Superior School of Agricultura "Luiz of Queiroz", University of São Paulo, Plant Production Department, São Paulo, Piracicaba – SP - Brazil. The experimental design used was of randomized blocks for an experiment in the field and randomized blocks in the factorial design for the others. The mechanical management of the different crops was carried out utilizing a KAMAQ lateral rotary mower Ninja Mac 260, designed to throw the cut crops down forming a layer of mulch around the citric plant. The data collected during the experiments were planta/m2 and plant/pot density, determination of some chemical conditions of the soil and weed dry biomass production in g/pot. In the carried out experiments, it could be observed that the use of mulches produced by different crops contributes significantly to reduce weeds. The best results were obtained in a natural infestation and the mixture of three cover crops. The fertilization in the whole area regardless the cover crops, presents a minor density of weeds in the lines of the citric plants. Furthermore, it can be concluded that the use of cover crops contributes widely to reduce weeds, supporting integrated management of weeds and providing with other inherent benefits.

Made available in DSpace on 2017-07-10T19:24:45Z (GMT). No. of bitstreams: 1 Marcia Maria Mauli.pdf: 735503 bytes, checksum: 95cbd8669a51013567022eb7120ce6ef (MD5) Previous issue date: 2009-02-02 / The adjustment of a cover crop to the agricultural system, with species whose chemical composition has substances able to control weeds, is a promising alternative to decrease herbicides application in agriculture. So, this trial aimed at analyzing the interference of black oats residues as well as black oat, common vetch and forage turnip consortium on weeds incidence, seeds emergence, seedling emergence, plants development, soybean productivity and its harvested seeds quality. The trial was carried out on field, from 2007 to 2008, with 5 m x 2 m plots and 1 m of border among them, distributed in seven randomized treatments with five replications each. During the crop development, the following parameters were evaluated: emergence speed index, plants development and weeds incidence. After harvest, in the laboratory, harvested seeds were evaluated according to: water content determination, weight of 100 seeds, purity, productivity, percentages of germination and vigor. It was a factorial experimental design with two factors plus one control and the averages were compared by the Tukey test at 5% level of significance. The weeds species did not differ statistically among the treatments. By and large, the treatments did not influence on plants heights, but increased the soybean productivity. However, the seeds showed less vigor when under the accelerated aging test. The seeds purity was inferior when they were under black oats crop. The weight of 100 seeds was changed by the treatments and they were heavier when grown on black oats. The other analyzed parameters did not show any statistic difference. It is, therefore, concluded that these species are good alternatives as winter covers in soybean crop under rotation system, since they improve the agronomic aspects of this culture. / A adequação da cobertura vegetal ao sistema agrícola, com espécies que possuam em sua composição química substâncias capazes de auxiliar no controle das plantas invasoras, é alternativa promissora para diminuir o uso de herbicidas na agricultura. Assim, o objetivo deste trabalho foi analisar a interferência dos resíduos culturais de aveia preta e também do consórcio de aveia preta, ervilhaca comum e nabo forrageiro sobre a incidência de plantas invasoras; emergência de plântulas, crescimento de plantas e produtividade da cultura de soja; além da qualidade da semente da soja colhida. O experimento foi conduzido em campo, nos anos 2007/2008, demarcando-se parcelas de 5 m x 2 m, com 1 m de bordadura entre elas e distribuídas em sete tratamentos, ao acaso, com cinco repetições cada. Durante o desenvolvimento da cultura, avaliaram-se os parâmetros: índice de velocidade de emergência, desenvolvimento de planta e incidência de espécies invasoras. Após a colheita, em laboratório, foram avaliadas as sementes colhidas pela determinação de teor de água, massa de 100 sementes, pureza, produtividade, porcentagem de germinação e vigor. O delineamento experimental foi em esquema fatorial com dois fatores com testemunha e as médias foram comparadas pelo teste de Tukey ao nível de 5% de significância. Observa-se que as espécies invasoras não diferiram estatisticamente entre os tratamentos. De maneira geral, os tratamentos não influenciaram na altura de plantas e aumentaram a produtividade da soja. Entretanto, apresentaram sementes menos vigorosas quando submetidas ao teste de envelhecimento acelerado. A pureza das sementes foi menor quando submetida ao cultivo com aveia preta. A massa de 100 sementes foi alterada pelos tratamentos, sendo maior em cultivo sob aveia preta. Os demais parâmetros analisados não mostraram diferenças estatísticas. Conclui-se, portanto, que tais espécies são indicadas como alternativa para cobertura de inverno, na rotação de culturas com a soja, pois melhoram os aspectos agronômicos da cultura.

Made available in DSpace on 2017-05-12T14:48:08Z (GMT). No. of bitstreams: 1 Marcia Maria Mauli.pdf: 735503 bytes, checksum: 95cbd8669a51013567022eb7120ce6ef (MD5) Previous issue date: 2009-02-02 / The adjustment of a cover crop to the agricultural system, with species whose chemical composition has substances able to control weeds, is a promising alternative to decrease herbicides application in agriculture. So, this trial aimed at analyzing the interference of black oats residues as well as black oat, common vetch and forage turnip consortium on weeds incidence, seeds emergence, seedling emergence, plants development, soybean productivity and its harvested seeds quality. The trial was carried out on field, from 2007 to 2008, with 5 m x 2 m plots and 1 m of border among them, distributed in seven randomized treatments with five replications each. During the crop development, the following parameters were evaluated: emergence speed index, plants development and weeds incidence. After harvest, in the laboratory, harvested seeds were evaluated according to: water content determination, weight of 100 seeds, purity, productivity, percentages of germination and vigor. It was a factorial experimental design with two factors plus one control and the averages were compared by the Tukey test at 5% level of significance. The weeds species did not differ statistically among the treatments. By and large, the treatments did not influence on plants heights, but increased the soybean productivity. However, the seeds showed less vigor when under the accelerated aging test. The seeds purity was inferior when they were under black oats crop. The weight of 100 seeds was changed by the treatments and they were heavier when grown on black oats. The other analyzed parameters did not show any statistic difference. It is, therefore, concluded that these species are good alternatives as winter covers in soybean crop under rotation system, since they improve the agronomic aspects of this culture. / A adequação da cobertura vegetal ao sistema agrícola, com espécies que possuam em sua composição química substâncias capazes de auxiliar no controle das plantas invasoras, é alternativa promissora para diminuir o uso de herbicidas na agricultura. Assim, o objetivo deste trabalho foi analisar a interferência dos resíduos culturais de aveia preta e também do consórcio de aveia preta, ervilhaca comum e nabo forrageiro sobre a incidência de plantas invasoras; emergência de plântulas, crescimento de plantas e produtividade da cultura de soja; além da qualidade da semente da soja colhida. O experimento foi conduzido em campo, nos anos 2007/2008, demarcando-se parcelas de 5 m x 2 m, com 1 m de bordadura entre elas e distribuídas em sete tratamentos, ao acaso, com cinco repetições cada. Durante o desenvolvimento da cultura, avaliaram-se os parâmetros: índice de velocidade de emergência, desenvolvimento de planta e incidência de espécies invasoras. Após a colheita, em laboratório, foram avaliadas as sementes colhidas pela determinação de teor de água, massa de 100 sementes, pureza, produtividade, porcentagem de germinação e vigor. O delineamento experimental foi em esquema fatorial com dois fatores com testemunha e as médias foram comparadas pelo teste de Tukey ao nível de 5% de significância. Observa-se que as espécies invasoras não diferiram estatisticamente entre os tratamentos. De maneira geral, os tratamentos não influenciaram na altura de plantas e aumentaram a produtividade da soja. Entretanto, apresentaram sementes menos vigorosas quando submetidas ao teste de envelhecimento acelerado. A pureza das sementes foi menor quando submetida ao cultivo com aveia preta. A massa de 100 sementes foi alterada pelos tratamentos, sendo maior em cultivo sob aveia preta. Os demais parâmetros analisados não mostraram diferenças estatísticas. Conclui-se, portanto, que tais espécies são indicadas como alternativa para cobertura de inverno, na rotação de culturas com a soja, pois melhoram os aspectos agronômicos da cultura.

Master of Science / Department of Entomology / Larry L. Buschman, Lawrent Buschman / This study evaluated whether using a cover crop with corn would increase the threat from spider mites in western Kansas because cover crops may serve as a winter host. This study also evaluated whether a cover crop could affect corn rootworm and other ground dwelling arthropods in the cornfield. In the first study, downy brome, Bromus tectorum L., was used as the winter cover crop. There were two trials repeated for three years each. Each trial included: two amounts of irrigation, downy brome, and herbicide to control weeds. In the first trial there were no significant differences in corn rootworm, Diabrotica virgifera LeConte, damage across treatments, because there were no differences in brome residue across the treatments. In the second trial, corn rootworm damage was significantly more in plots with higher amounts of downy brome residue. There were no differences in numbers of spider mites: Banks grass mites, Oligonychus pratensis (Banks) or twospotted spider mites, Tetranychus urticae Koch, across treatments. Spider mite populations appeared to be suppressed by the predatory mite Neoseiulus spp., which also overwintered in the cover crop. Corn rootworm samples taken from a no-till irrigation experiment were variable among irrigation treatments but indicated a trend for rootworm damage to increase with increasing irrigation. In the second study, winter wheat, Triticum aestivum L., was used as the winter cover crop. There were three trials repeated for three years each. Each trial included two amounts of irrigation and winter wheat and three amounts of herbicide to control weeds. Upon completion of the agronomy trials, the plots were split into two subplots and one was tilled. Pitfall traps were installed to capture ground dwelling arthropods: (Coleoptera: Carabidae), wolf spiders (Araneae: Lycosidae) and crickets (Orthoptera: Gryllidae). Four carabid genera were more common under no-till conditions. One was more common in tilled plots. Five carabid genera were more common in plots with a history of high weed densities. Two carabid genera were more numerous in plots with the history of a cover crop. Crickets were more common under no-till conditions. Wolf spiders were more common in no tillage with a history of a cover crop.

This study investigates the impact on water quality of combined agricultural best management practices cover crop and minimum tillage, alongside an examination of techniques used to collect those samples. Edge-of-field (EOF) water quality samples were collected from 11 working farms during a two-year paired field experiment. Results showed significant reductions in nutrient concentrations, increased discharge, and mixed findings regarding nutrient mass transport post-treatment. A suite of EOF collection techniques were compared using in-situ automated water sampling systems sampling the same runoff events. Sampling protocols influenced nutrient concentrations in composite samples, but unexpected variance in velocity sensors affected measured discharge, making it challenging to confidently attribute differences in nutrient loading estimates to sampling protocol. The findings provide regionally specific evidence for mitigating on-farm nutrient enrichment in the Lower Mississippi Alluvial Valley and enhancing monitoring techniques.

Time of planting plays a critical role in nitrogen (N) uptake by rye cover crop (CC). Even a few days of delay in planting can severely decrease CC performance. Evaluating the amount of N accumulation related to time of planting is critical to the farmer who has to optimize the winter rye planting date based on completion of corn harvest, suitable weather conditions and time availability for fall manure application. Winter rye cover crop was planted at 6 planting dates in fall from mid August to early October at weekly intervals from 2004 to 2009. The results suggest that delay from critical planting date (CPD) will decrease rye N uptake dramatically. Suggested CPDs for northwest parts of Massachusetts are not applicable because they are too early (third to fourth week of August). CPDs for central parts of the State are from first to second week of September. Farmers in these zones can take advantage of cover crop by a better time management and planting no later than vii CPD. In Eastern areas of Massachusetts CPD is the third week of September. By evaluating the effect of planting date on rye growth and N accumulation throughout the State, this model provides a powerful decision making tool for increasing N recovery and reducing nutrient leaching. Sixteen units of cost effective and accurate automated lysimeters were designed and installed to measure post-harvest nitrate leaching from a rye cover crop field during the falls and winters of 2007 to 2009. The electronic system was designed to monitor soil tension and apply the equal amount of suction to the sampling media. Hourly data from soil tension and vacuum applied to the system were collected and stored by each unit. A safety system was designed for protecting vacuum pump against unexpected major vacuum leakage events. The controller can be easily reprogrammed for different performance strategies. Other major parts of lysimeter included the power supply systems, vacuum pump, vacuum tanks, sampling jars, suction cups and plates, and electronic valves. The electronic system showed a very reliable and accurate performance in the field condition.

Incidence and severity of southern blight caused by Sclerotium rolfsii Sacc. is increasing in the mid-Atlantic region of the U.S. affecting both conventional and organic vegetable production systems. Traditional southern blight management relied on fumigants and fungicides with often inconsistent and uneconomical results. Moreover, with the phase-out of methyl bromide, and the high cost and toxicity of other available fumigants, it is necessary to identify effective and economical southern blight management alternatives. Therefore, the objectives of this research were to 1) evaluate the effect of planting date and potato (Solanum tuberosum L.) cultivar selection on southern blight incidence and tuber yield and quality; 2) compare potato cultivar tuber susceptibility to S. rolfsii in post-harvest settings; and 3) assess the suitability of six cool-season cover crop biomasses and three locally organic materials as carbon sources for anaerobic soil disinfestation (ASD) treatments and their impact on S. rolfsii viability and soil. In a three-year field study, ten commercial potato cultivars and four planting dates per year were evaluated on the Eastern Shore of Virginia. Later potato plantings generally produced greater disease incidence (85-94%) and lower tuber yield (1.8-9.4 Mg ha-1) and quality (47-78%), likely driven by humid, warm weather later in the season that was conducive to disease and detrimental to the potato crop. While no potato cultivar was completely immune to S. rolfsii incidence, cultivar 'Accumulator' consistently had one of the lowest disease incidences (12-71%) and greatest tuber yield among cultivars (6.2-37.3 Mg ha-1), and 'Adirondack Blue' and 'Red Norland' had the overall greatest disease incidence (33-100%). Following harvest of the field experiment, the susceptibility of tubers from the ten cultivars to post-harvest rot caused by S. rolfsii was compared in a laboratory experiment under controlled conditions. 'Atlantic' followed by 'Accumulator' were the least susceptible (3.7-12.6 g of diseased tissue) whereas 'Adirondack Blue', followed by red-skinned potato cultivars had the greatest severity of post-harvest tuber rot (12-17.5 g of diseased tissue). Following three weeks of ASD treatments in growth chamber pot experiments utilizing nine carbon sources incubated at 15/25°C 12/12-h cycle, most carbon sources induced soil anaerobicity (33-90 % iron oxide paint removal), but they did not reduce sclerotial viability compared to nonamended aerobic controls. However, most amended soils undergoing ASD induced greater soil microbial activity (0.7-2.0 % CO2 in vol.) compared to nonamended controls (0.1-0.7 CO2 in vol.), increased soil pH, and some amendments increased soil nitrate accumulation. Overall, results of these studies indicate that southern blight can be effectively managed in potato by coupling early planting dates with cultivar selection, but though promising, additional studies are needed to determine the parameters to effectively decrease S. rolfsii viability with ASD treatments. / Doctor of Philosophy / The fungal disease southern blight, caused by the soilborne plant pathogen Sclerotium rolfsii Sacc., is increasing in the mid-Atlantic U.S. The increase of southern blight is likely due to a multitude of issues such as climate fluctuations, reduction in the use of fumigants, increased soil organic matter through conservation practices, and cropping systems that favor soilborne pathogens. Traditional management of S. rolfsii relied on pesticides and fumigants, but control was often inconsistent and expensive. Moreover, the use of some soil fumigants has been restricted due to environmental concerns, which has limited the options for the management of plant pathogens present in the soil, and management alternatives are needed. Through a series of field, laboratory, and greenhouse experiments, this study 1) evaluated the effect of planting date and potato (Solanum tuberosum L.) cultivar selection on southern blight incidence and tuber yield and quality; 2) compared potato cultivar tuber susceptibility to S. rolfsii in post-harvest settings; and 3) assessed the suitability of six cool-season cover crop biomasses and three locally-sourced organic materials as carbon sources in anaerobic soil disinfestation (ASD) treatments and their impact on S. rolfsii viability and soil. Results of a three-year field study demonstrated that an integrated approach to the management of southern blight that utilizes moderately resistant potato cultivars such as 'Accumulator' and early (March to early April) planting dates will minimize risk of disease and maximize tuber yield. Following harvest, inoculation of potato tubers under controlled conditions revealed that the cultivar 'Atlantic' followed by 'Accumulator' can avoid greater losses due to less tuber rot, while 'Adirondack Blue' followed by red-skinned potatoes have a greater risk of suffering post-harvest tuber decay from southern blight. The anaerobic soil disinfestation (ASD) treatments examined in this study indicated that cover crops biomass and poultry litter are suitable carbon sources to induce soil anaerobic conditions, but they may not reduce the survival of S. rolfsii propagules if treatment temperatures are below 25°C. However, ASD showed benefits such as increased activity of soil microbial communities compared to nonamended soil, increased soil acidity, and some amendments such as mushroom compost, poultry litter, and Austrian winter pea (Pisum sativum subsp. arvense) can contribute soil nutrients such as nitrate. Overall, this research demonstrates that choosing less susceptible cultivars coupled with early planting dates can minimize the negative impact of southern blight on potato yields and quality, and consequently minimize the use of pesticides as the main option to control southern blight on potato across the mid-Atlantic region. Though promising, additional studies are needed to determine the parameters that optimize ASD as an alternative to manage S. rolfsii with ASD treatments.

High-biomass cover cropping enhances marketable yields in organic production of vegetables, linked to the improvement of soil quality and weed control. Although, during transition from chemical to organic cover-cropping production, especially with no-till systems, reduction of nitrogen availability to the main crop and increase in weed and pest pressure may occur. In 2004-2005, summer and fall broccoli (Brassica oleraceae L. Botrytis Group) crops were grown in twin rows on permanent (controlled traffic) raised beds (185-cm wide). Before broccoli transplanting, high-biomass cover crops were grown in specific bed areas. Legumes (Vicia villosa, Glycine max L., and Crotolaria juncea L.) on bed tops (grow zones) and grass species (Secale Cereale L., Setaria italica L., and Sorghum bicolor X S. bicolor var. Sudanese) in the alleyways (bed shoulders and bottoms). Experimental treatments were tillage (conventional, CT; and no-tillage, NT), farmscaping (with and without), and nitrogen sidedressing (with and without, applied 3 weeks after transplanting as a mixture of sodium nitrate - 22 kg N ha-1 - and feathermeal - 44 kg N ha-1). Weeds were managed by mechanical cultivation in CT and a spot weeding by hand in NT treatments. High numbers of beneficial insects (Cotesia glomerata, Cotesia orobenae and Diadegma insulare) kept the primary insect pest population (Pieris rapae, Evergestis rimosalis (Guenee), and Plutella xylostella) at a pest to predator ratio below 4:1. Although the excellent insect pest control was attributed to the farmscape plantings, pest level and crop yields were not significantly affected by farmscaping (likely due to the close proximity of the farmscaped plots (10-50m from non-farmscaped)). Broccoli yield averaged 62% higher in fall than summer (12.1 vs. 7.5 t ha-1) likely due to cool weather conditions during broccoli head development (October), increasing head size, uniformity, and marketability. In 2004, broccoli yield in CT plots was either equal or slightly higher than NT (9.5 vs. 9.0 t ha-1). However, in 2005, broccoli yield in CT plots was significantly higher in both spring (8.8 vs. 6.8 t ha-1; p = 0.0258) and fall crops (13.5 vs. 12.3 t ha-1 with p = 0.0484). Nitrogen sidedressing improved yield in all plots (9.8. vs. 12.7 t ha-1) and particularly in NT (8.6 vs. 12.1 t ha-1), indicating that availability and/or synchrony of nitrogen was a limiting factor. Incorporating high-N legume residues in the grow zones resulted in a lesser N response in CT. / Master of Science

O objetivo deste trabalho foi testar um manejo Alternativo em um pomar convencional de Tangerina Murcote (Citrus reticulata, Blanco X Citrus sinensis, Osbeck) enxertadas sobre limão cravo (Citrus limonia, Osbeck), com utilização de composto fermentado Bokashi, avaliando seu efeito sobre a compactação do solo, colonização radicular de fungos micorrízico arbusculares (FMA) nativos, desempenho nutricional, produção e as características tecnológicas dos frutos. O experimento foi delineado separando-se um hectare dentro de um talhão em produção, com 10 anos de idade, onde foram suspensas as aplicações de fertilizantes e defensivos químicos, inclusive os herbicidas, substituindo-os por fontes de nutrientes de baixa solubilidade, de forma que viessem incentivar as interações biológicas, em especial as associações micorrízicas. Para estimular a cobertura vegetal, foi aplicado o composto fermentado Bokashi sobre a vegetação espontânea da linha e entrelinha, procedendo-se o roço mecânico, cuja área foi denominada ‘tratamento Alternativo’. Uma área equivalente e contígua, onde os tratos culturais e fitossanitários convencionais foram mantidos, foi utilizada para fins de comparação, sendo esta denominada ‘tratamento Convencional’. Os parâmetros eleitos para comparação foram: resistência do solo à penetração, densidade radicular superficial, colonização de fungos micorrízicos arbusculares nativos, assim como a quantidade de esporos viáveis no solo, análise de conteúdo de nutriente foliar e produtividade e qualidade de fruto, sendo avaliadas 10 parcelas de 3 plantas para cada tratamento. O manejo Alternativo, com aplicação de composto fermentado Bokashi sobre a vegetação espontânea na entrelinha, propiciou maior cobertura vegetal, 107,5% a mais, avaliado em janeiro de 2005, principalmente de gramíneas, a qual reduziu a resistência do solo à penetração ao longo do experimento, denotando melhora no estado de compactação do solo em relação ao tratamento Convencional. Também, houve melhor desenvolvimento do sistema radicular superficial, maior índice de colonização radicular de fungos micorrízicos arbusculares (FMA) nativos nas plantas do tangor ‘Murcott’, em média 10% superior, e em conseqüência, maior quantidade de esporos viáveis no solo, sendo em média 23% superior ao tratamento Convencional. Em termos nutricionais, a quantidade aportada de K no tratamento Alternativo não foi suficiente para suprir adequadamente as necessidades das plantas, demonstrando que é preciso dar maior atenção a esse nutriente nas propostas alternativas de manejo para citros. O teor de B foliar se apresentou significativamente superior e em níveis crescentes ao longo do experimento, atingindo patamares 280% maiores do que o tratamento Convencional, com teores de até 161,35 mg.kg-1, resultado altamente desejável para este nutriente em citros. Apesar da redução na produtividade inicialmente, o tratamento Alternativo foi superior em massa de frutos por planta na última avaliação, em agosto de 2004, sendo 58,2 kg. planta-1 contra 42,9 kg.planta-1 do Convencional, embora o tamanho dos frutos e a acidez total tenham sido prejudicados pela deficiência do K. Isso demonstra que em pomar de idade avançada o manejo alternativo deve ser adotado de forma gradual. Em avaliações complementares foi observado que o manejo Alternativo proporcionou melhor equilíbrio na população de Orthezia praelonga, tendo 0,54% das plantas atacadas, contra 14,06% no manejo Convencional. / The objective of this study was to test an alternative management in a conventional orchard of ‘Murcott’ tangor (Citrus reticulata, Blanco X Citrus sinensis, Osbeck) grafted on rangpur lime (Citrus limonia, Osbeck) using fermented compost Bokashi, in order to evaluate its effect on soil decompaction, root colonization of indigenous arbuscular mycorrhizal fungi (AMF), nutritional performance, yield and technological characteristics of fruits. The experiment was set by separating one hectare plot in a ten year old yielding orchard, where chemicals fertilizers and pesticides, including herbicides, were discontinued and replacing them by sources of low solubility nutrients and alternative pest control, with the purpose to encouraging the biological interactions, mainly mycorrhizal associations. To stimulate vegetal covering, a fermented compost Bokashi was applied on the spontaneous vegetation of the row e interrow, mechanical clearing was used, and the area was designated ‘alternative treatment’. An equivalent and adjoining area, where conventional cultural and phythosanitary treatments were maintained was used for comparative purposes, and was designated ‘conventional treatment’. The parameters chosen for comparison were: soil resistance to penetration, surface root density, colonization of indigenous arbuscular mycorrhizal fungi, as well as amount of viable spores in the soil, analysis of foliar nutrient content, and fruit yield and quality. Ten plots of 3 plants per each treatment were evaluated. The alternative management with application of fermented compost Bokashi on the spontaneous vegetation on the interrow provided a 107.5% increase in vegetal covering, mainly grasses, measured in January 2005, which decreased soil resistance to penetration and resulted in an improvement in soil compaction state as compared with the conventional treatment. Also, there were an improved development of surface root systems, a higher rate of root colonization of indigenous arbuscular mycorrhizal fungi (AMF) in plants of ‘Murcott’ tangor, averaging 10% higher and, consequently, a higher amount of viable spores in the soil, an average of 23% higher than of the conventional treatment. In nutritional terms, the input of K in the alternative treatment was not enough to supply adequately the needs of the plants, indicating that more attention is required in relation to this nutrient in alternative proposals of citrus management. The foliar content of B was shown to be significantly higher and at increasing rates along the experiment, reaching levels 280% higher than those of the conventional treatment, having reached contents of up to 161.35 mg.kg-1, a highly desirable result for citrus nutrition. Despite the initial yield decrease, the alternative treatment showed a higher fruit mass per plant in the last evaluation in August 2004, i.e. 58.2 kg.plant-1 against 42.9 kg.plant-1 in the conventional treatment, even though fruit size and total acidity were impaired by K deficiency. This shows that, in older aged orchard, an alternative management should be introduced gradually. Subsequent appraisals showed that the alternative treatment provide a better equilibrium in the population of Orthezia praelonga, i.e. 0.54% of attacked plants against 14.06% in the conventional treatment.