Alternative Control of Plant Pathogen Fungi Through Ethanolic Extracts of Avocado Seeds (Persea Americana Mill.)

ABSTRACT The aim of this study was to evaluate the antifungal action of ethanolic extracts of avocado seeds, by conducting two experiments in the laboratory of plant pathology of EPAMIG SUL/Lavras, MG, Brazil, in a completely randomized design with three replicates. The first consisted of the following treatments ('Breda' 3%, 'Breda' 2%, 'Margarida' 3%, 'Margarida' 2%, Control, and Ethanol) testing its inhibitory effect on two fungal species (Colletotrichum gloeosporioides and Monilinia fructicola) and the second consisted of different concentrations of extracts (0%, 0.25%, 0.50%, 0.75%, 1.0%, 1.5%, and 2.0%) on the fungus F fructicola. The evaluations were performed at three times (7, 14, and 21 days of incubation) by measurements of the mycelial diameter using a digital caliper. The data were submitted to analysis of variance and the averages were compared by Scott-Knott test at 5% probability. The results demonstrated the positive potential of the ethanolic extracts of avocado seed on the mycelial development of fungi M. fructicola and C. gloeosporioides during the evaluated days.

Influência do zinco na incidência de doenças do cafeeiro / Zinc influence on coffee diseases

Em cafeeiros, poucos estudos foram feitos relacionando aumento ou diminuição da resistência das plantas às doenças, com alteração dos níveis de nutrientes utilizados. Com este trabalho, objetivou-se estudar os efeitos do sulfato de zinco aplicado isoladamente, e associado com fungicidas e cloreto de potássio sobre a ferrugem, cercosporiose e manchas foliares do cafeeiro. O trabalho foi desenvolvido em uma lavoura de café em produção, onde foram testados oxicloreto de cobre, tebuconazole, sulfato de zinco + cloreto de potássio e sulfato de zinco e nas subparcelas foram realizadas diferentes concentrações de sulfato de zinco: ausência, 0,3 por cento, 0,6 por cento e 1,2 por cento. Verificou-se que os tratamentos com oxicloreto de cobre e tebuconazole reduziram a incidência e severidade de ferrugem, a incidência de cercosporiose, de manchas foliares (phoma e ascochyta) e a desfolha, independente das concentrações de sulfato de zinco utilizadas. Concentrações de sulfato de zinco na faixa de 0,6 por cento - 0,75 por cento apresentaram menor severidade da ferrugem e o aumento nas concentrações de sulfato de zinco aumentou a incidência de cercosporiose, manchas foliares e a desfolha dos cafeeiros.

The are few studies have been done related to the increase or decrease of disease resistance in coffee plants, with alteration from plant nutrient levels. The ain of this work was to verify the effect of zinc sulfate, applied either alone or in association with fungicides, and the effect of potassium chloride on coffee leaf rust, brown-eyes and leaf stains in coffee plants. Copper oxichloride, tebuconazole, sulfate of zinc + potassium chloride and sulfate of zinc were applied on plots and concentrations of zinc sulfate (0,0 percent, 0,3 percent, 0,6 percent and 1,2 percent) were applied on sub plot. Treatments with copper and tebuconazole reduced the incidence and severity of rust, the incidence of brown-eyes and stains leaf (phoma and ascochyta) and the defoliate independent of the zinc sulfate concentrations. Concentration of zinc sulfate varying from 0,6 percent to 0,75 percent shawed less rust severity. As the concentration of zinc sulfate increased, the severity of brown-eyes disease, leaf stains (phoma and ascochyta) and coffee defoliate tree also increased.

Progresso da ferrugem e da cercosporiose do cafeeiro consorciado com grevílea, com ingazeiro e a pleno sol em Lavras - MG / Progress of rust and coffee plant cercosporiose mixed with grevílea, with ingazeiro and in the full sunshine in Lavras - MG

Com o presente trabalho, objetivou-se avaliar a incidência da ferrugem e da cercosporiose do cafeeiro em diferentes sistemas de cultivo, agroflorestais e a pleno sol, através da curva de progresso dessas doenças. Utilizou-se o delineamento inteiramente casualizado, com três tratamentos e sete repetições. Os tratamentos foram compostos por cafeeiros consorciados com ingazeiro, cafeeiros consorciados com grevílea e cafeeiros cultivados convencionalmente a pleno sol. As avaliações foram realizadas mensalmente no período de abril de 2001 a março de 2003. Realizou-se o cálculo da área abaixo da curva de progresso da doença (AACPD), a qual foi submetida à análise de variância. Para a incidência da ferrugem do cafeeiro o consórcio cafeeiro x ingazeiro mostrou-se com maiores índices da doença, sendo que os tratamentos consórcio cafeeiro x grevílea e cafeeiro a pleno sol não diferiram entre si e apresentaram menores incidências da doença. Diminuição na luz solar direta e maior umidade podem ter favorecido a ferrugem no sistema cafeeiro x ingazeiro. Para a incidência de cercosporiose, os cafeeiros a pleno sol obtiveram maiores valores de incidência da doença, seguidos por cafeeiros x grevílea, e menores taxas da doença foram observadas no consórcio cafeeiros x ingazeiro. A incidência de radiação solar direta pode ter favorecido a maior incidência de cercosporiose nos cafeeiros a pleno sol.

The present work aimed to evaluate the incidence of rust and coffee plant cercosporiose in different systems of agroforest cultivation and in the full sunshine through the progress curve of those diseases. The completely randomized design with three treatments and seven replicates was utilized. The treatments were made up of coffee plants mixed with ingazeiro, coffee plants mixed with grevílea and coffee plants cultivated conventionally in the full sunshine. The evaluations were performed monthly during the period of April 2001 to March 2003. The calculation of the area bellow the disease progress curve (ABDPC), which was submitted to the variance analysis. For the incidence of the coffee plant rust, the coffee plant x ingazeiro mixing presented the highest indices of the disease, the treatments coffee plant x grevílea mixing and coffee plant in the full sunshine did no differ from each other and presented the smallest indices of the disease. Decrease in the direct solar light and higher humidity may have supported rust in the coffee plant x ingazeiro system. For the incidence of cercosporiose, the coffee plants in the full sunshine obtained higher values of incidence of the disease followed by coffee plants x grevílea and lowest rates of the disease were found in the coffee plant x ingazeiro mixings. The incidence of direct solar radiation may have supported the highest incidence of cercosporiose on the coffee plants in the full sunshine.