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Bacterial leaf blight occurs in almost the entire Brazilian territory and can cause significant economic damage. However, its effects can be curtailed with the following tools that aid in quantification for carrying out the best severity assessment that can be applied to the studies used in its control. The objective of this study was to develop and validate a diagrammatic scale to quantify the severity of bacterial leaf blight in maize caused by Pseudomonas avenae. Corn leaves were collected with different levels of disease severity, and the total leaf area as well as the injured area of the middle third of each leaf was measured. From this, the minimum and maximum limits of the disease and, subsequently, four intermediate levels were determined whilst taking into account the law of visual stimulus of Weber-Fechner. Levels 1.5%, 2.5%, 9%, 18%, 46%, and 70% were selected with validation performed by eight evaluators, four inexperienced and four experienced. These evaluators estimated the severity values, initially without the use of the proposed diagrammatic scale and in a second attempt with the use of the scale. We concluded that it was possible to improve the accuracy and precision of the evaluators when they used the scale as a tool to assess the severity of bacterial leaf blight on corn leaves.

Nematode control strategies are limited and alternative control is demanded. The main aim was to evaluate control potential of Hohenbuehelia spp. (Hohenbuehelia mastrucata, Hohenbuehelia barbatula, Hohenbuehelia bullulifera, Hohenbuehelia portegna, Hohenbuehelia petaloides and Hohenbuehelia paraguayensis) and Trichoderma koningiopsis against Meloidogyne javanica in bean plants in greenhouse. The parameters evaluated were the number of galls and egg masses which were evaluated in three root regions: basal, intermediate and tip; nematode reproduction factor; vegetal growth parameters (plants height on V1, V2, V4, and R5 growth stages, root length, dry weight of root and aerial part dry weight); Treatments were composed by individual interactions of each fungal isolate with 4,000 eggs of M. javanica, having a total control (bean) and a partial control (bean + nematode) arranged in completely randomized design with four repetitions. Data were tested by Scott–Knott (5%). For vegetal growth parameters, there was only significance for dry weight of roots. All species were able to control nematodes.

Control of phytonematodes is very hard and requires a combination of techniques to succeed. Alternative control through plant extracts may result in the discovery of nematicide substances. Research aimed at evaluating the effect of 33 plants submitted to aqueous extraction against Panagrellus redivivus in vitro. Concentrations were prepared at 1.25, 2.5, 5, 10, and 20%. Monitoring happened at 0, 6, 12, 24 and 30 hours after preparation. Counting considered dead nematodes subtracted from alive ones. Juveniles were also counted, and extract efficiency was expressed in percentage of control or stimuli. Data were submitted to variance analysis. Significant results got with the Scott-Knott test (5%), and multiple linear regression analysis. Extracts were observed acting as controllers, but also as stimulators to nematode reproduction. The best controlling performance was set by Carica papaya (-66% at 20%; -33.7% at 10%), Euphorbia milii (-37% at 20%), Psychotria carthagenensis (-25.5% at 2.5%), Clusia variegate (-22% at 20%), and Zamioculcas zamiifolia (-21.5% at 20%). Stimulator extracts were Mentha villosa at 10% (+148%) and 2.5% (+131.5%), followed by Aloe vera (+123% at 5%), Schinus molle (+112.5% at 10%), Schefflera arboricola (+93.5% at 5%), C. variegate (+89% at 5%), and S. molle (+88% at 5%). Some extracts kept population stable throughout the experiment, presenting lower control indexes. Besides an additive effect, there was an individual influence of concentration or time on control. RESUMO O controle de fitonematoides é muito difícil e requer uma combinação de técnicas para ter sucesso. O controle alternativo via extrato vegetal pode resultar na descoberta de substâncias nematicidas. Esta pesquisa objetivou avaliar o efeito de 33 plantas submetidas à extração aquosa contra Panagrellus redivivus in vitro. As concentrações foram preparadas a 1,25; 2,5; 5; 10; e 20%. O monitoramento ocorreu em 0, 6, 12, 24 e 30 horas após a preparação. Para a contagem, foram considerados nematoides mortos subtraídos dos vivos. Nematoides jovens também foram contados, e a eficiência dos extratos foi expressa em porcentagem de controle ou de estímulo. Os dados foram submetidos à análise de variância. Resultados significativos foram analisados pelos testes de Scott-Knott (5%) e análise de regressão múltipla. Foram observados extratos agindo como controladores, bem como estimuladores da reprodução de nematoides. A melhor performance de controle foi obtida por Carica papaya (-66% a 20%; -33,7% a 10%), Euphorbia milii (-37% a 20%), Psychotria carthagenensis (-25,5% a 2,5%), Clusia variegate (-22 a 20%) e Zamioculcas zamiifolia (-21,5% a 20%). Os extratos estimuladores foram Mentha villosa a 10% (+148%) e 2,5% (+131,5%), seguido por Aloe vera (+123% a 5%), Schinus molle (+112.5% a 10%), Schefflera arboricola (+93.5% a 5%), C. variegate (+89% a 5%) e S. molle (+88% a 5%). Alguns extratos mantiveram a população estável durante todo o experimento, apresentando menores índices de controle. Além do efeito aditivo houve uma influência individual da concentração e do tempo no controle.

RESUMO Extratos vegetais podem induzir mecanismos de resistência de plantas em função da presença de compostos com características eliciadoras. O objetivo deste estudo foi avaliar o efeito do extrato bruto de alecrim nas concentrações 0%; 1%; 2,5% e 5% sobre a atividade de peroxidase, polifenoloxidase e fenilalanina amônia-liase (FAL) em soja inoculada com Macrophomina phaseolina. Foram retiradas amostras nos tempos 0, 36, 72, 120, 168, 216 e 264 h após o tratamento. Nas amostras retiradas do colo das plantas, para peroxidase, as concentrações mais elevadas do extrato proporcionaram dois picos de indução. Houve constante incremento na atividade de polifenoloxidase desde 36 até 120 h após o tratamento para a concentração 5%. Para FAL apenas a concentração 5% promoveu incremento 83% e 130% maior nos tempos 168 e 216 h após o tratamento, respectivamente. Para as atividades na raiz, peroxidase novamente apresentou dois picos de incremento para concentração 5%, a polifenoloxidase foi 426% maior na concentração 5% às 216 h após o tratamento e a atividade de FAL apresentou incremento de 340% no tempo 216 h após o tratamento com 5% do extrato. Estes resultados indicam o potencial do extrato de alecrim em induzir a atividade de enzimas de defesa em colo e raiz de soja. ABSTRACT Plant extracts may induce resistance mechanisms in plants due to the presence of compounds with eliciting characteristics. The aim of this study was to evaluate the effect of rosemary crude extract at the concentrations 0%; 1%; 2.5% and 5% on the activity of peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase (PAL) in soybean plants inoculated with Macrophomina phaseolina. Samples were collected at 0, 36, 72, 120, 168, 216 and 264 hours after treatment. Considering the samples collected at the collar region of plants, for peroxidase, the highest concentrations of the extract provided two induction peaks. There was a constant increase in polyphenol oxidase activity from 36 to 120 hours after treatment at 5% concentration. For PAL, only the concentration of 5% led to increases 83% to 130% higher at 168 and 216 hours after treatment, respectively. For the activities in the root, peroxidase again showed two increment peaks at 5% concentration; polyphenol oxidase was 426% higher at 5% concentration at 216 hours after treatment and PAL activity showed an increase of 340% at 216 hours after treatment with 5% extract. These results indicate the potential of rosemary extract to induce the activity of defense enzymes in the collar region and in the root of soybean plants.

The planting of RR2 Intacta soybeans by farmers has been expanding strongly. However, some visual injuries have been noted after glyphosate application. The aim of this study was to evaluate the influence of glyphosate application on chlorophyll, photosynthesis and water use of four Intacta RR2 soybean cultivars. The experiment was conducted in a greenhouse, in a randomized block design with a 3 × 4 factorial scheme, consisting of three glyphosate rates and four soybean cultivars. The glyphosate formula used was isopropylamine salt + potassium salt. The parameters analyzed were phytotoxicity at 7, 14, 21 and 28 days after application, and total chlorophyll index at 0, 3, 7, 14, 21, 28, 35, 42 and 49 days after application. Furthermore, 40 days after application, the net CO2 assimilation rate (A), transpiration rate (E), stomatal conductance (G), and internal CO2 concentration (Ci) were evaluated as well. The water-use efficiency (WUE) and carboxylation efficiency were calculated. The data were submitted to analysis of variance and compared by the Tukey’s test (p ≤ 0.05), followed by regression analysis. The phytotoxicity influence could be seen until 21 days after application, in which Monsoy 6210 IPRO cultivar was the most injured. The increasing doses promoted a reduction of the chlorophyll level up to 35 days after application in Monsoy 6410 IPRO. The cultivars tested here showed similar chlorophyll index values. On the 3rd, 7th and 14th DAA (Fig. 5a–c), there was a significant linear decline in the chlorophyll index with rising glyphosate dose for all four cultivars. The chlorophyll index cultivars were not influenced by the doses on the 42nd and 49th DAA. There was no difference in water use and carboxylation efficiency. The parameters A, E and A/Ci showed a positive correlation as the doses increased, while Ci declined, in both cultivars. The application of glyphosate on these soybean cultivars causes different injuries according to the sensitivity. In general, RR2 soybeans have the ability to recover from visual intoxication injuries and reestablish the normal chlorophyll production and photosynthetic parameters after glyphosate application.

Swine wastewater (SWW) is a residue from pig farming that presents a high load of nutrients and organic matter. The appliance of organic matter in soil alters the microbial dynamic and may suppress soilborn phytopathogens. This study aimed at evaluating the inhibition on mycelial growth of Sclerotinia sclerotiorum and Sclerotium rolfsii in vitro under SWW doses. Hereupon, three kilograms of a soil classified as red dystroferric latosol was collected and sieved. Half of it was autoclaved. SWW was incorporated at doses of 0 mL, 2.5 mL, 5 mL, 10 mL and 20 mL in both soil conditions, autoclaved and not autoclaved. Afterwards, 130 grams of each soil was separately put into Petri plates above what a thin layer (≅ 5 mL) of Water-Agar (2%) medium was carefully spread over. Above this agar layer, one disk (6 mm diameter) of pure mycelium from each fungal grown in Potato Dextrose Agar medium was individually placed on the center of each plate. Daily evaluations on mycelial growth measuring were taken and ended when mycelium in control plates (without SWW addition) reached plate borders. Results indicated that in autoclaved soil condition, the inhibition was proportional to the dose, what is to say that the higher the dose the less the mycelial growth. In not autoclaved soil there was no significant difference among treatments, suggesting stimuli on suppression effect for both pathogens caused by SWW. In addition, the confirmed potential of SWW as a suppressor of S. sclerotiorum and S. rolfsii leads to promising investigations on other phytopathogens hard to control.

Biological control is a method of controlling pests through the use of other living organisms. The purposes of this study were to test Hohenbuehelia species as biological control agents against Panagrellus redivivus in vitro, evaluating nematodes influence on mycelia growth; establishing daily indexes for predation and growth and setting predation percentage. Five species previously identified as 436-Hohenbuehelia mastrucata (Nematoctonus hamatus), 528-H. bullulifera (not described so far), 581-H. paraguayensis (N. sp.), 582-H. sp. (N. sp.) and 631-H. portegna (N. campylosporus) were submitted to anamorphic purification directly from basidioma. Afterwards, 100 nematodes were added to each pure colony for predation test. Evaluation started right after 24 hours of nematode-fungus interaction. Immobilized and/or penetrated nematodes were counted and mycelia growth was measured. Results were subjected to variance analyses. Hohenbuehelia mastrucata had the best performance in growth speed, followed by H. portegna and H. paraguayensis; Nematodes multiplyied much but none specie grew more as an influence of their movement under mycelium, however all species formed trap devices and some of them produced adhesive or repelent substances. Trap devices were formed in control plates also. The plates of H. paraguayensis without nematodes grew more than treatments. Cumulative predation of H. portegna was the highest at 24 (195.5%) and 48 hours (235%). At the last evaluation day, H. paraguayensis preyed the same amount (185.75%) than H. portegna, followed by H. mastrucata (109.51%). Resulst of predation daily indexes displayed chronological activity for each isolate, where H. portegna was very reactive at first 24 hours, H. mastrucata raised its predacious activity in 48 hours being constant from this time on and H. paraguayensis pointed out itself at 72 hours. Other species presented low predation and growth indexes throughout experiment.

This research aimed to evaluate the nematophagous ability of 4077-Verticillium chlamydosporium var. chlamydosporium and 4466-Hirsutella thompsonii isolates and relate mycelia growth to the influence provoked by movement of nematodes. Each fungus grew in PDA (potato, dextrose, agar) medium end up to pure colonization. Then, ten mycelia plugs of 8 mm diameter were removed from colony borders and transferred to the center of ten Petri plates containing water-agar 2% medium. These plates were previously divided into four quadrants that received a number of 25 individuals of free-living nematodes (Panagrellus redivivus), composing a total of 100 nematodes per plate. Evaluations started after 24 hours of interaction, considering predation percentage and mycelia growth as stimuli of nematodes presence. Results showed growing predation performance to both isolates, being higher for V. chlamydosporium var. chlamydosporium since from first evaluation time, controlling more than 50% of nematode population initially added. Its predation potential was 39.2%, 38.4% and 48.35% higher than H. thompsonii at first, second and third evaluation day, respectively. Generally, nematodes did not stimulate mycelia growth, unless for H. thompsonii at 72 hours of interaction compared to control plates (without nematodes). Stress resulting from isolates transference from PDA to water-agar 2% resulted in sparse mycelia growth and it could have affected the predation performance of H. thompsonii that controlled nematodes in low levels throughout experiment. Independently of predation level, pictures revealed that both isolates has ability to control P. redivivus through hyphae penetration.

Aiming the reduction and rationalization on the use of chemical products to control phytopathogens, the present study had as main objective to evaluate the effect of lemongrass' byproducts (Cymbopogon citratus) (essential oil, crude aqueous extract and citral) on the inhibition of the mycelial growth of Alternaria solani and Septoria lycopersici, on the control of tomato's (Solanum lycopersicum) diseases cultivated at organic system, post-harvest as well as analyze the economic viability of these products. The treatments were: T1 (C. citratus crude aqueous extract - CAE 1%), T2 (CAE 5%), T3 (CAE 10%), T4 (CAE 15%), T5 (C. citratus essential oil- EO 10 μL.L-1), T6 (EO 100 μL.L-1), T7 (EO 200 μL.L-1), T8 (EO 400 μL.L-1), T9 (citral - CI 10 μL.L-1), T10 (citral 100 μL.L-1), T11 (citral 200 μL.L-1), T12 (citral 400 μL.L-1), T13 (control treatment), T14 (bordeaux mixture 1%), T15 (commercial product registered to organic agriculture based on fermented plant extracts) and T16 (tomato cultivated at conventional system), the last used only for the experiment of post-harvest and economic analysis. The in vitro assays were conducted on a completely randomized design with five replicates. The evaluations of the mycelial growth initiated one day after the disk was peaked in the center of the petri dish and lasted until the control took over the entire dish. All byproducts provided significant inhibiting effect on the mycelial growth in both phytopathogens, with linear correlation. S. lycopersici demonstrated to be less sensitive to treatments with the byproducts of C. citratus. The essential oil and its major component, the citral, were superior to treatment with EAB, which, at low concentration and initial assessments, provided stimulation of mycelial growth, indicating the occurrence of the phenomenon known as hormesis. The field experiment was carried out on randomized block design, with four replicates and five plants per plot. It was used the Cordillera cultivar (hybrid F1), intercropped with coriander (Coriandrum sativum). 18 harvests were made and 7 severity evaluations of septoria leaf spot, which occurred naturally in the field. The evaluated variables were: severity (%), area under the disease progress curve (AUDPC), average fruit weight, production (kg) per plant, number of fruits per plant, total and marketable yield, fruit size and defect and diameter of the stem. The severity was affected by the treatments, with T12 and T14 the lowest rates at the final evaluation. The bordeaux mixture had the lowest AUDPC rate, followed by treatments 7, 8, 10, 11 e 12. The total production, as well as the fruit size, weight, number of fruits per plant and the diameter of the stem didn't differ significantly with the treatments. Treatments 7, 8, 10, 12 e 14 to the commercial production and treatments 3, 5, 6, 7, 8, 10, 11, 12 e 14 to fruit defect had a statistical difference which was better than that of the control. The post-harvest evaluation was conducted on completely randomized design, with four replicates and six fruit per plot. It was made physical analysis (color, total and partial weight loss, volume, viability and specific weight), chemical (pH, total soluble solids SST, titratable acidity AT, and ratio) and sensorial (firmness to touch, general external appearance, pulp characteristics, general internal appearance, scent, texture, flavor, odd flavor, sweetness, acidity and global quality). No significant difference was found between most of the organic treatments at the physical and chemical analysis. The most significant difference was observed when comparing the two cropping systems. The tomatoes produced in the conventional system showed less weight loss and pH and those produced in the organic system had a higher ratio and sensory quality. To do the economic viability analysis, the information of conventional cultivation was obtained from a producer at Maringá's region, who used the same cultivar. The conventional system spent 2,33 times more with the phytosanitary management, considering that the number of pulverizations was more frequent than on organic system. The treatment that provided greater financial return was the Bordeaux mixture (T14), that exceeded R$ 7,522.8 to the control and R$ 9,439.6 to the conventional crop system. All by-products of C. citratus treatments provided higher returns than the control and conventional crop systems. Visando a redução e a racionalização da utilização de produtos químicos no controle de fitopatógenos, o presente trabalho objetivou avaliar os efeitos da utilização de subprodutos (óleo essencial, extrato bruto aquoso e citral) de capim-limão (Cymbopogon citratus) na inibição do crescimento micelial de Alternaria solani e Septoria lycopersici, no controle de doenças de tomateiro (Solanum lycopersicum) cultivado em sistema orgânico de produção, na pós-colheita de tomate, bem como analisar a viabilidade econômica da utilização desses produtos. Os tratamentos que compuseram os estudos foram: T1 (Extrato aquoso bruto de C. citratus - EAB 1%); T2 (EAB 5%); T3 (EAB 10%); T4 (EAB 15%), T5 (Óleo essencial de C. citratus - OE 10 μL.L-1); T6 (OE 100 μL.L-1); T7 (OE 200 μL.L-1); T8 (OE 400 μL.L-1); T9 (citral - CI 10 μL.L-1); T10 (CI 100 μL.L-1); T11 (CI 200 μL.L-1); T12 (CI 400 μL.L-1); T13 (Testemunha); T14 (Calda bordalesa 1%); T15 (Produto comercial registrado para agricultura orgânica a base de extratos vegetais fermentados); e T16 (tomate cultivado em sistema convencional), o último utilizado apenas no experimento de pós-colheita e na análise econômica. Os ensaios in vitro foram conduzidos em delineamento experimental inteiramente casualizados com cinco repetições. As avaliações de crescimento micelial iniciaram um dia após o disco de micélio ser repicado para o centro da placa de petri e perduraram até que a testemunha tomasse toda a placa. Todos os subprodutos proporcionaram efeito significativo na inibição do crescimento micelial em ambos fitopatógenos, com resposta linear crescente. O fungo S. lycopersici demonstrou ser menos sensível aos tratamentos com os subprodutos de C. citratus. O óleo essencial e o seu componente majoritário, citral, foram superiores aos tratamentos com EAB, que, em baixa concentração e nas avaliações iniciais, proporcionou estímulo do crescimento micelial, indicando a ocorrência do fenômeno conhecido como hormese. No experimento de campo, o delineamento utilizado foi blocos ao acaso, com quatro repetições e cinco plantas por parcela. A cultivar utilizada foi a Cordillera (híbrido F1) consorciada com coentro (Coriandrum sativum). Foram realizadas 18 colheitas e 7 avaliações de severidade da septoriose, que ocorreu naturalmente na lavoura. As variáveis avaliadas foram: severidade (%), área abaixo da curva de progresso da doença (AACPD), massa média dos frutos, produção por planta (kg), número de frutos por planta, produção total e comercial, tamanho e defeito dos frutos e diâmetro do colo da planta. A aplicação dos tratamentos 12 e 14 proporcionou menor severidade da septoriose. A calda bordalesa apresentou o menor índice de AACPD, seguido dos tratamentos 7, 8, 10, 11 e 12. A produção total, bem como o tamanho dos frutos, a massa, o número de frutos por planta e o diâmetro do caule, não foram alterados significativamente pelos tratamentos. Os tratamentos 7, 8, 10, 12 e 14, para a produtividade comercial, e os tratamentos 3, 5, 6, 7, 8, 10, 11, 12 e 14, para defeitos dos frutos, apresentaram diferença estatística, sendo melhores que a testemunha. Na avaliação de pós-colheita, conduzida em delineamento inteiramente casualizados, com quatro repetições e seis frutos por parcela, foram realizadas análises físicas (coloração, perda de massa parcial e total, volume, viabilidade e peso específico), químicas (pH, sólidos solúveis totais - SST, acidez titulável - AT e ratio) e sensoriais (firmeza ao toque, aparência geral externa, característica da polpa, aparência geral interna, aroma, textura, sabor, sabor estranho, doçura, acidez e qualidade global). Não foram constatadas diferenças entre a maioria dos tratamentos orgânicos nas análises químicas e físicas. A maioria das diferenças significativas foi verificada na comparação entre os dois sistemas de cultivo. Os tomates produzidos no sistema convencional apresentaram menor perda de massa e pH e os produzidos no sistema orgânico apresentaram maior ratio e qualidade sensorial. Na análise de viabilidade econômica, as informações referentes ao cultivo convencional foram obtidas de produtor da região de Maringá que utilizou a mesma cultivar. O sistema convencional gastou 2,33 vezes mais com o manejo fitossanitário, considerando que o número de pulverizações foi maior do que o praticado no cultivo orgânico. O tratamento que proporcionou maior receita líquida total foi a calda bordalesa (T14), superando em 7522,8 reais à testemunha e em 9439,6 reais ao cultivo convencional. Todos os tratamentos com subprodutos de C. citratus proporcionaram maior receita líquida que a testemunha e que o cultivo em sistema convencional de produção. ix, 129 f

Corn employs a strategic key in the chain production of animal protein (meat, eggs, and byproducts) which consumption grows every year. The impact of leaf disease in corn crop is growing continuously fostering higher survival of pathogens in the field. Then, the objective of this work was to evaluate in the field the effect of potassium phosphite application to control leaf diseases on productivity and occurrence of sour grains. It was carried out three trials at Cocari Technological Center, Mandaguari, PR, at different times, to eleven corn hybrids. The following treatments were compared: T1 - phosphite 2.0 L.ha-1 for V6 phenological stage, T2 - phosphite 2.0 L.ha-1 for V10 stage (pretasseling), T3 - phosphite 1.0 L.ha-1 for V6 and V10 stages, T4 - phosphite 2.0 L.ha-1 for V6 and V10 stages, T5 - phosphite 1.0 L.ha-1 for V6 stage followed by epoxiconazole + piraclostrobina (Ópera®) 0.6 L.ha-1 + mineral oil (Assist®) at 0.5% for V6 stage, T6 - fungicide 0.6 L-ha-1 + mineral oil at 0.5 % for V10 stage, T7 - control having no application. All phosphite potassium treatments reduced the rate of severity and/or AACPD of diseases, and showed higher efficiency to Cercospora stain control, followed by white stain, Helminthosporioses common, and less for blight. The treatment T4 followed by T2 were the most promising, although the fungicide resulted in lower rates of severity and AACPD and the best levels of disease control. The treatment did not reduce the incidence of sour grains, but resulted in higher productivity. O milho desempenha função estratégica na cadeia produtiva da proteína animal (carnes, ovos e derivados), cujo consumo cresce a cada ano. O impacto das doenças foliares na cultura do milho vem crescendo continuamente propiciando maior sobrevivência dos patógenos no campo. Assim, o objetivo deste trabalho foi avaliar, em campo, o efeito da aplicação do fosfito de potássio no controle das doenças foliares, na produtividade e na ocorrência de grãos ardidos. Foram conduzidos três experimentos no Centro Tecnológico da Cocari, Mandaguari - PR, em épocas diferentes, em onze híbridos de milho. Foram comparados os seguintes tratamentos: T1 - fosfito 2,0 L.ha-¹ no estádio fenológico V6, T2 - fosfito 2,0 L.ha-¹ no estádio V10 (pré-pendoamento), T3 - fosfito 1,0 L.ha-¹ nos estádios V6 e V10, T4 - fosfito 2,0 L.ha-¹ nos estádios V6 e V10, T5 fosfito 1,0 L.ha-¹ no estádio V6 seguido do fungicida, epoxiconazole + piraclostrobina (Ópera®) 0,6 L.ha-¹ + óleo mineral (Assist®) a 0,5% no estádio V10, T6 - fungicida 0,6 L.ha-¹ + óleo mineral a 0,5% no estádio V10, T7 - testemunha sem aplicação. Todos os tratamentos de fosfito de potássio reduziram os valores de severidade e/ou a AACPD das doenças e demonstraram maior eficiência para o controle da mancha de cercospora, seguido da mancha branca e da helmintosporiose comum e menor para ferrugens. Os tratamentos T4 seguidos pelos T2 foram os mais eficientes, porém o fungicida apresentou os menores valores de severidade e AACPD e os melhores níveis de controle das doenças. Os tratamentos não diminuíram a incidência de grãos ardidos, porém apresentaram incremento de produtividade. xii, 76 f