Intensidade da cercosporiose em mudas de cafeeiro em função de fontes e doses de silício. Fitopatologia Brasileira 30: 582-588. 2005. RESUMOO objetivo deste estudo foi avaliar o efeito dos silicatos de cálcio e de sódio sobre a intensidade da cercosporiose (Cercospora coffeicola) em mudas de cafeeiro (Coffea arabica), cultivar Catuaí IAC 99, nas doses 0; 0,32; 0,64; 1,26 g de SiO 2 .kg -1 de substrato. Foram realizadas cinco avaliações quinzenais nas quais se quantificou o número de plantas doentes, o número de folhas lesionadas por planta, o número de lesões por folha e o número total de lesões por planta. Essas avaliações foram utilizadas para construir a área abaixo da curva de progresso da doença. Ao término das avaliações, foram determinados os teores de macro, micronutrientes, silício e lignina na parte aérea das mudas de cafeeiro. A menor área abaixo da curva de progresso do total de lesões foi obtida com a dose de 0,84 g.kg -1 de silicato de sódio. Observouse decréscimo linear para área abaixo da curva de progresso do número de plantas doentes e aumento na concentração de lignina nas folhas até a dose de 0,52 g.kg -1 de silicato de sódio, enquanto no caule houve acúmulo de SiO 2 até 0,53 g.kg Palavras-chave adicionais:Coffea arabica, Cercospora coffeicola, silicato de sódio, silicato de cálcio. ABSTRACT Effect of silicon doses and sources on the intensity of the brown eye spot of coffee seedlingsThe objective of this work was to evaluate the effect of calcium and sodium silicate on the intensity of brown eye spot (Cercospora coffeicola) in coffee (Coffea arabica) seedlings (Catuaí IAC 99) by using doses (0; 0.32; 0.63 and 1.26 g of SiO 2 .kg -1 ) of substrate. Five evaluations were done by counting the number of diseased plants, number of leaves with lesions, number of lesions per leaf and total number of lesions per plant. The concentration of macro, micronutrients, silicon and lignin in the leaves was determined at the end of the experiment. The lowest area under the disease progress curve of the total number of lesions was observed with 0.84 g.kg -1 of sodium silicate. Diseased plants were found to have a linear decrease of area under the disease progress curve and an increase in the concentration of lignin up to the dose of 0.52 g.kg -1 of sodium silicate. The increase of sodium silicate and dose application into the soil up to 0.53 g.kg -1 decreased the concentration of SiO 2 on the stem.Additional keywords: Coffea arabica, Cercospora coffeicola, sodium silicate, calcium silicate.

Coffee is a crop of great economic importance in many countries. The organic coffee crop stands out from other production systems by aiming to eliminate the use of synthetic fertilizers and pesticides. One of the most important limitations in the organic system is the management of diseases, especially coffee rust, which is considered the main disease of this crop. Coffee rust causes a production slump of up to 50%, significantly affecting the profitability of coffee growers. This work aims to review the integrated rust management in organic coffee crop in different producing countries. Regarding the disease management strategies, this review addresses the use of rust-resistant cultivars, cultural management, biological control, use of plant extracts, and chemical rust control by cupric fungicides. Considering the importance of the organic system, the increase in world coffee consumption, and the potential market for this kind of coffee, this review may help researchers and producers looking for alternative strategies to control rust in an organic coffee cultivation system.

The use of resistance inducers is a promising development in the management of plant diseases, owing to their ability to control a broad spectrum of pathogens and improve the efficacy of fungicides. This study evaluates different sources of phosphonates (potassium, manganese, copper), a formulation prepared from the by‐products of the coffee industry (Greenforce CuCa), as well as the effects of their application, alone or in association with fungicide, in the management of two important coffee fungal diseases in Brazil: leaf rust and brown eye spot, caused by Hemileia vastatrix and Cercospora coffeicola, respectively. The effect of these products on defoliation, productivity and chemical composition of coffee beans (content of trigonelline, chlorogenic acid, caffeine and total soluble solids) was evaluated. Among all the alternative products tested individually, potassium phosphonate (P2O5—33.6% + K2O—29%) stood out, particularly for rust control, which was similar to the results of fungicide treatments. Treatments with fungicide, Greenforce CuCa and cuprous oxide, individually, caused less plant defoliation. Regarding the chemical composition of the coffee beans, the manganese phosphonate treatment showed the highest values for trigonelline, chlorogenic acid, caffeine and total soluble solid content. The results of this study show that resistance inducers can be useful in disease management, may come to eventually replace traditional fungicides and can also contribute to the beverage quality.

No abstract

RESUMO O presente trabalho objetivou estudar o efeito do silício na intensidade da cercosporiose e na nutrição mineral de mudas de cafeeiro. No experimento 1, testou-se seis doses de ácido silícico (0, 0,5; 1; 2; 4 e 6 g kg–1 de solo) em mudas da cultivar Catuaí Vermelho IAC 99 inoculadas com o fungo Cercospora coffeicola. No experimento 2, foram realizadas microanálises de raios-X para a avaliação de nutrientes presentes nas folhas das mudas de cafeeiro das cultivares Topázio MG1190 e Icatu Precoce IAC 3282, inoculadas e não inoculadas com C. coffeicola, com e sem silicato de cálcio (1 g kg-1 de solo). Com o aumento das doses de ácido silícico observou-se redução na área abaixo da curva de progresso do número de lesões por folha (AACPNLF), redução linear nos teores foliares de magnésio e fósforo e aumento nos teores de enxofre e cobre. Os teores foliares de boro apresentaram comportamento quadrático, diminuindo com o aumento das doses de ácido silícico e aumentando a partir da dose de 4 g kg-1 de solo. Em microanálise de raio X, mudas de cafeeiro com cercosporiose apresentam menores picos de potássio e cálcio, independente da cultivar utilizada.

No abstract

Soybean seed infected with Colletotrichum truncatum is an important source of primary inoculum for anthracnose epidemics. Based on differences in the GAPDH gene sequences of Colletotrichum species, one pair of species-specific primers, CtruncF1/ CtruncR1, was designed to accurately detect C. truncatum in soybean seed samples. The primers amplified only a single PCR band of 211 bp from C. truncatum. SYBR Green qPCR using these primers enabled the detection of DNA of the target fungus in inoculated soybean seeds and in naturally infested seeds. The sensitivity of the method was 0.000253 ng/μL of C. truncatum DNA template, with an efficiency of 1.78 and a Ct of 30.09. These species-specific primers may be useful for certification of soybean seeds aimed at avoiding introduction of the pathogen into soybean-producing regions.

No abstract