Copper formulations in bacterial blight control and toxic effects on coffee seedlings

Bacterial blight of coffee (Pseudomonas syringae pv. garcae) is an important coffee disease and can be controlled using antibiotics and copper-based compounds. However, copper-based compounds raise doubts among coffee growers regarding bacterial blight control efficiency and phytotoxic potential. In this work, coffee plants were sprayed with different copper molecules in order to study their efficiency on bacterial blight control and the phytotoxic potential. Seven copper formulations, cuprous oxide, copper oxychloride, copper nitrate, copper hydroxide 1 (water-dispersible granules) and 2 (concentrated suspension), copper sulfate 1 (complexed with gluconic acid) and 2 (Bordeaux mixture) were studied. The copper formulations efficiency was compared with the antibiotic kasugamycin, saline solution, and control. In controlled environmental conditions of temperature, relative humidity, and photoperiod, coffee seedlings were sprayed with the treatments and after 24 hours they were inoculated with Pseudomonas syringae pv. garcae suspension. Disease incidence and severity assessments were performed in a 2-day interval during a 16-day period. Phytotoxicity incidence and severity, mapping, and quantification of copper on the leaf tissue surface, dried leaves weight, and total copper leaf content were assessed 16 days after pathogen inoculation. Data were submitted to the Scott-Knott test (p < 0.05). Cuprous oxide and copper sulfate 2 proved most efficient to bacterial blight control, causing lower phytotoxicity effect, best covering, and persistence on leaf tissues. Copper nitrate and copper sulfate complexed with gluconic acid were more phytotoxicity compared to other copper formulations.

Modelagem geoestatística da sigatoka-negra e sua relação com a fertilidade do solo / Geostatistical modeling of black-sigatoka and relation to soil fertility

Objetivou-se, com a realização do presente trabalho, caracterizar a variabilidade espacial da sigatoka-negra, utilizando-se metodologia de análise geoestatística para verificar sua relação com a fertilidade do solo na cultivar Grande Naine. O experimento foi realizado no município de Registro, SP. Demarcou-se, no campo, uma malha regular de 30 x 30 m, totalizando-se 30 pontos amostrais georreferenciados com aparelho de GPS. Foram realizadas avaliações da severidade da sigatoka-negra, com auxílio de uma escala diagramática. Coletaram-se amostras de solo na camada de 0-20 cm, para análise de fertilidade. Com base na análise do semivariograma isotrópico, verificou-se a forte dependência espacial da severidade da doença, com alcance de 25,28 m. Os mapas de krigagem demonstraram um padrão agregado e da relação negativa da severidade da doença com os teores de potássio e positiva com teores de enxofre no solo.

The objective in this research was to characterize the spatial variability of the Black Sigatoka disease, using the geostatistic analysis methodology to identify its relation to soil fertility in the Grande Naine cultivar. The experiment was conducted in the city of Registro, São Paulo state, Brazil. A regular 30 x 30m field mesh was demarcated, using a Geographical Positioning System in the experimental field, composed of a total of 30 sampling points or georeferences. Evaluations of the severity of the Black Sigatoka were conducted using a diagrammatic scale. Soil samples were collected in the 0 - 20cm layer for fertility analysis. Based on the isotropic semivariogram, a clustered spatial dependence of the disease severity, with a range of 25.28m was verified. The kriging maps demonstrated an aggregate pattern and negative relationship of the severity of the disease to potassium and positive with levels sulphur in the soil.

Efeito do tipo de substrato e da presença de adubação suplementar sobre o crescimento vegetativo, nutrição mineral, custo de produção e intensidade de cercosporiose em mudas de cafeeiro formadas em tubetes / Effects of substrate type and supplementary fertilization on vegetative growth, mineral nutrition, production costs, and brown eye spot of coffee seedlings in stiff plastic containers

A utilização de tubetes para produzir mudas de cafeeiro (Coffea arabica L.) tornou-se uma realidade. Objetivando avaliar o uso de substratos adubados ou não com fertilizante de liberação gradual e seus efeitos na nutrição, na formação, na cercosporiose e nos custos de produção de mudas de cafeeiro em tubetes, conduziu-se um experimento em viveiro, em esquema fatorial (4x2) com quatro substratos combinados com duas adubações, tendo quatro repetições. As parcelas foram constituídas por 16 tubetes de 120 mL, considerando-se como plantas úteis as seis centrais. Os tratamentos consistiram dos substratos S1= Substrato comercial I, S2 = Substrato comercial II, S3 = Substrato de eucalipto e S4 = 80 por cento esterco de curral + 20 por cento terra de subsolo, todos com e sem adubação com fertilizante de liberação gradual. No geral, os melhores substratos para formação de mudas de cafeeiro em tubetes foram os substratos não comerciais ou orgânicos, independentemente de receberem ou não adubação suplementar. Observou-se redução da cercosporiose com a nutrição mineral, principalmente com o cálcio. Com a utilização de todos os substratos houve ganho econômico em relação ao custo por milheiro de mudas. A maior economia foi obtida com o substrato S4, seguida do substrato S3, com melhor relação custo/benefício.

The utilization of stiff plastic containers for producing coffee seedlings (Coffea arabica L.) is a reality. Aiming to evaluate the effects of substrate type enriched or not with slow-release fertilizer on vegetative growth, mineral nutrition, production cost and, brown eye spot of coffee seedlings, an experiment was conducted in the plant nursery. The experimental design was a factorial scheme with four substrates in the presence and absence of supplementary fertilization, with four replicates. The plots were made of 16 containers of 120 ml, using six central plants for evaluation. The treatments consisted of S1 = Commercial Substrate I, S2 = Commercial Substrate II, S3 = Eucalyptus Substrate and S4 = 80 percent bovine manure + 20 percent subsoil material with and without fertilization. In general, the best substrates for formation of coffee seedlings were not commercial substrates or organic, regardless of fertilization. The brown eye spot was reduced with balanced nutrition, mainly with calcium. All substrates provide economic return. The largest economy was found in substrate S4, followed by S3, showing the highest coast/benefit rate.