Exogenous application of salicylic acid to control coffee rust

The exogenous application of salicylic acid can induce plant resistance against pathogens. However, little is known about the potential uses of this bioregulator for controlling coffee diseases. In this study, we assessed the effect of applying salicylic acid (SA – 150 mg L-1) on the management of coffee rust (Hemileia vastatrix) in a 7-year-old coffee plantation with low crop load (651.6 kg ha-1 in 2017). For comparison, plants were sprayed with protectant fungicide (copper hydroxide – CH) and standard fungicides (SF) used by local farmers (boscalid, pyraclostrobin + epoxiconazole, and copper hydroxide). Non-treated plants were included as a negative control. Five monthly applications were performed from November 2016 to March 2017. Rust incidence and severity, defoliation, and growth of plagiotropic branches were evaluated monthly. The activity of catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and total proteins was assessed one day after the first, third, and fifth product applications. Compared to untreated plants, SA reduced the severity and incidence of rust from 36.3 to 54.7%, while CH and SF reduced disease from 31.8 to 54.6% and from 83.8 to 88%, respectively. SA reduced defoliation by 54.1%. SA increased the concentration of CAT, APX, and SOD after the first application. However, this effect was not observed after subsequent applications. Foliar application of SA reduces the severity and incidence of coffee rust and defoliation in plants with a low crop load.

Antifungal activity using medicinal plant extracts against pathogens of coffee tree / Atividade antifúngica utilizando extratos de plantas medicinais contra fitopatógenos do cafeeiro

Generally, the medicinal plants have antifungal substances that can be used for the plant protection against phytopathogens. The objective of this study was to know the efficiency of aqueous extracts from medicinal plants against the major etiological agents of coffee tree. The aqueous extracts used were extracted from bulbs of Allium sativum, leaves of Vernonia polysphaera, Cymbopogon citratus, Cymbopogon nardus, Cordia verbenacea, Eucalyptus citriodora, Ricinus communis, Azadirachta indica, Piper hispidinervum and flower buds of Syzygium aromaticum. The etiological agents considered for this study were Cercospora coffeicola, Colletotrichum gloeosporioides, Fusarium oxysporum, Phoma tarda, Rhizoctonia solani and Hemileia vastatrix. The screening for harmful extracts was done based on mycelial growth and conidial germination inhibition. All experiments performed were in vitro conditions. The inhibition of mycelial growth was performed mixing the extracts with the PDA. This mixture was poured in Petri dishes. On the center of the dishes was added one PDA disc with mycelium. It was incubated in a chamber set to 25ºC. The evaluation was done daily by measuring the mycelial growth. The germination assessment was also performed with Petri dishes containing agar-water medium at 2%. These were incubated at 25ºC for 24 hours. After this period the interruption of germination was performed using lactoglycerol. The experiments were conducted in a completely randomized design. The most effective plant extracts against the micelial growth and conidial germination were V. polysphaera, S. aromaticum and A. sativum.

Geralmente, as plantas medicinais têm substâncias antifúngicas que podem ser utilizadas para a proteção das plantas contra fitopatógenos. O objetivo deste estudo foi conhecer a eficiência de extratos aquosos de plantas medicinais contra os principais agentes etiológicos do cafeeiro. Os extratos aquosos utilizados foram extraídos de bulbos de Allium sativum, folhas de Vernonia polysphaera, Cymbopogon citratus, Cymbopogon nardus, Cordia verbenacea, Eucalyptus citriodora, Ricinus communis, Azadirachta indica, Piper hispidinervum e botões florais de Syzygium aromaticum. Os agentes etiológicos considerados neste estudo foram Cercospora coffeicola, Colletotrichum gloeosporioides, Fusarium oxysporum, Phoma tarda, Rhizoctonia solani e Hemileia vastatrix. A triagem dos extratos foi realizada com base no crescimento micelial e na inibição da germinação de conídios. Todos os experimentos foram realizados em condições in vitro. A inibição do crescimento micelial foi realizada misturando-se os extratos com PDA. Esta mistura foi vertida em placas de Petri. No centro das placas foi adicionado um disco de PDA com micélio. Incubou-se em câmara programada para 25°C. A avaliação foi feita diariamente através da medição do crescimento micelial. O experimento sobre a germinação também foi realizado com placas com meio ágar-água a 2%. Estas foram incubadas durante 24 horas. Após este período, a interrupção da germinação foi realizada utilizando lactoglicerol. Os experimentos foram conduzidos em delineamento inteiramente casualizado. Os extratos de plantas mais eficazes contra o crescimento micelial e germinação de conídios foram V. polysphaera, S. aromaticum e A. sativum.

Rust resistance in Arabic Coffee cultivars in northern Paraná

The objective of the study was to evaluate the resistance to rust in coffee cultivars developed by research institutes of Brazil in Paraná state. Resistance to the local leaf rust races was assessed in high disease intensity field conditions at Londrina and Congonhinhas in 2009 and 2010.The cultivars were developed by the EPAMIG/UFV, IAPAR, IAC and MAPA/Procafé. The resistant standard 'IAPAR 59' and the susceptible standards Catuaí Vermelho IAC 144' and 'Bourbon Amarelo' were used. A randomized block design with three replications and plots with 10 plants was used. A scale from 1 to 5 based on the rust intensity was used to evaluate the resistance. The Catiguá MG 1, Catiguá MG 2, IAPAR 59, IPR 98, IPR 104, Palma II, Paraíso H-419-10-6-2-5-1, Paraíso H-419-10-6-2-10-1, Paraíso H-419-10-6-2-12-1, Pau Brasil MG 1 and Sacramento MG 1 cultivars presented complete resistance to rust at Londrina and Congonhinhas. The cultivars derived from the Catucaí germplasm were susceptible or showed different levels of partial resistance. Partial resistance to the rust was observed in several coffees derived from "Hibrido de Timor". 'Acauã' and 'Obatã IAC 1669-20' presented complete resistance at Londrina, but at Congonhinhas, they were partially resistant, indicating that different rust races have occurred at these two locations.

Progresso temporal da ferrugem alaranjada em cultivares de cafeeiro no oeste de São Paulo / Temporal progress of orange rust in coffee cultivars in western Sao Paulo

A ferrugem é a doença mais comum das lavouras de café. O trabalho estudou nos cultivares de Coffea arabica L. Acaiá IAC 474-19, Catuaí Amarelo IAC 47, Icatu Amarelo IAC 2944, Icatu Vermelho IAC 4045, Obatã IAC 1669-20 e Apoatã IAC 2258 (Coffea canephora Pierre ex Fhroen) a incidência da ferrugem. O ensaio foi realizado em Adamantina, SP, onde os cafeeiros foram plantados no espaçamento de 4,0 x 2,0 m, com duas plantas por cova e dispostos em 6 linhas com 15 a 20 covas cada. No período entre junho de 2008 a dezembro de 2009, quinzenalmente, coletou-se ao acaso 30 folhas obtidas nos terços superior, médio e inferior dos cafeeiros e calculou-se a porcentagem das folhas com sintomas característicos da ferrugem. Calculou-se a área abaixo da curva de progresso da ferrugem para cada um dos cultivares. Constatou-se a doença na Icatu Amarelo IAC 2944 e Icatu Vermelho IAC 4045, cultivares descritos como resistentes/tolerantes à ferrugem. Concluiuse que a incidência diferiu entre os cultivares e diminuiu com o aumento da temperatura, mas não com a precipitação pluvial. A incidência da doença menor que 5% nos cafeeiros ocorreu com temperaturas máximas médias mensais maiores que 30º C

Rust is the most common disease in the coffee plantations. This work aimed to evaluate the incidence of coffee rust in the following cultivars of Coffea arabica L.: Acaiá IAC 474-19, Catuaí Amarelo IAC 47, Icatu Amarelo IAC 2944, Icatu Vermelho IAC 4045, Obatã IAC 1669-20 and Apoatã IAC 2258 (Coffea canephora Pierre ex Fhroen). The experiment was conducted in Adamantina, northwest region of the state of São Paulo, Brazil. The coffee trees were planted at a spacing of 4.0 x 2.0 m with two plants per hole. Each plot consisted of six lines with 15 to 20 holes each. From June 2008 to December 2009, 30 leaves were randomly collected from the upper, middle and bottom portions of the trees. The leaf rust was found in all cultivars, including on Catuai Amarelo IAC 2944 and Vermelho IAC 4045, although both cultivars are considered resistant to the disease in field conditions. The infections differed significantly among cultivars. The rust symptoms declined with increasing temperature, and the rainfall did not affect the incidence of disease. The less-than-5% infection rate coincided with the occurrence of maximum monthly mean temperatures greater than 30º C.

Progresso da ferrugem do cafeeiro irrigado em diferentes densidades de plantio pós-poda / Progress of rust in coffee plants in various densities of cultivation in irrigated planting after pruning

Objetivou-se, no presente trabalho, avaliar o efeito de diferentes critérios para manejo da irrigação em quatro densidades de plantio, sob sistema de gotejamento na incidência e severidade da ferrugem do cafeeiro e avaliar a influência do enfolhamento na curva de progresso dessa doença. Conduziu-se, o experimento, em área experimental da Universidade Federal de Lavras MG, utilizando a cultivar Rubi MG-1192 com seis anos. O delineamento experimental foi em blocos ao acaso com quatro repetições. Os tratamentos foram constituídos por quatro parcelas representadas pelas densidades de plantio (convencionais e adensados): 2500 (4,0x1,0 m), 3333 (3,0x1,0 m), 5000 (2,0x1,0 m), 10000 (2,0x0,5 m) plantas ha-1, quatro subparcelas sendo: irrigações quando a tensão da água no solo atingiu valores de 20 e 60kPa; irrigações utilizando o manejo do balanço hídrico (calculado através do software IRRIPLUS), com turnos de irrigação fixos de três dias por semana e uma testemunha sem irrigação, perfazendo um total de 16 tratamentos. Cada subparcela foi constituída por 10 plantas, sendo consideradas como plantas úteis as seis centrais. Foram avaliadas a incidência e severidade da ferrugem e a porcentagem de enfolhamento das plantas de cafeeiros. Após análise estatística, os dados foram convertidos em área abaixo da curva de progresso da doença e do crescimento. Verificou-se que os critérios para manejo da irrigação influenciaram a curva de progresso do crescimento, porém, não interferiu na curva de progresso da incidência e da severidade da ferrugem. Os sistemas de plantios adensados favoreceram a incidência da ferrugem. Mas as densidades de plantio não interferiram no enfolhamento.

The objective of this study was to evaluate the effect of different irrigation controls implemented in four planting densities on a system of drip on the incidence and severity of rust and to assess the influence of leaf growth on the progress curve of this disease. The experiment was conducted in the experimental area of the Federal University of Lavras - MG, using the cultivar Rubi MG-1192 with 6 years. The experimental design was randomized blocks with four replicates. The treatments consisted of four tranches represented by planting densities (conventional and non-conventional): 2500 (4.0 x1.0 m), 3333 (3.0 x 1.0 m), 5000 (2.0 x 1.0 m), 10,000 (2.0 x 0.5 m) plants / ha, with four subplots: the tension when irrigation water in the soil reaches values of 20 and 60kPa; using water balance management of irrigation (calculated by the software IRRIPLUS) with rounds of irrigation fixed three days per week and a control without irrigation, making a total of 16 treatments. Each subplot line consisted of 10 plants with the six central plants considered as useful. The incidence and severity of rust and the percentage of grown of coffee plants were evaluated. After statistical analyses the data were converted to area under the curve of disease and growth progress. It was verified that the management of irrigation influenced the progress curve of growth, but it did not interfere in the progress curve of the incidence and severity of coffee rust. The dense system of plantation favored the incidence of rust. However, the planting densities did not affect growth.

Variabilidade em dez populações de Hemileia vastatrix em relação à germinação e ao comprimento do tubo germinativo em quatro temperaturas / Variability in ten populations of Hemileia vastatrix for germination and germinative tube length under four temperatures

Neste trabalho, objetivou-se verificar o efeito da temperatura na germinação e no comprimento do tubo germinativo em diferentes populações de H. vastatrix (PHVs), sob quatro temperaturas. Realizou-se um bioensaio com dez PHVs, com suspensão de urediniósporos a 0,5mg/mL em solução aquosa (0,05 por cento) de tween 80. Duas gotas de cada suspensão foram depositadas em lâminas de microscópio recobertas com camada de poliestireno e colocadas em gerbox contendo papel de filtro umedecido para constituir câmara úmida. Os gerboxes foram mantidos fechados, no escuro, a 15ºC, 20ºC, 25ºC e 30ºC, por 24 horas. O ensaio foi conduzido em fatorial 10 x 4, sendo dez isolados, quatro temperaturas e duas repetições. Avaliaram-se a germinação e o comprimento do tubo germinativo. Houve variabilidade entre as PHVs quanto à temperatura ótima para germinação e alongamento do tubo germinativo.

The objective of this work was to verify the effect of temperature in germination and germ tube length in different populations of H. vastatrix (PHVs) temperatures. A bioassay was performed with ten PHVs, using an urediniospore suspension of at 0.5mg/mL in aqueous solution (0.05 percent) of tween 80. Two drops of each suspension was deposited on a microscope coverslip, covered with a polystyrene layer and incubated in gerbox containing a watered filter paper to work as a wet chamber. The gerbox was kept closed, in the dark, at 15, 20, 25 and 30ºC for 24 hours. The assay was carried out in a factorial design 10 x 4, with ten isolates, four temperatures and two replicates represented by two drops of the suspension. Germination percentage and germ tube length were assessed. There was variability among PHVs for the optimum temperature for germination and elongation of the germ tube.

Resistance to leaf rust in coffee carrying S H3 gene and others S H genes

The aim of this work was to evaluate the resistance to rust in coffee carrying S H3 gene and other S H genes. Twenty one CIFC’s coffee trees with several resistance genes S H were evaluated in field conditions. All the evaluated coffees carrying Sh3 gene presented resistance to the rust. It was possible that rust races with the virulence gene v3 in the Paraná State didn’t exist. The S H3 gene in combination with genes S H5, S H6, S H7, S H8, S H9 and S H? would be very important to obtain cultivars with more durable resistance to the rust.

O objetivo deste trabalho foi avaliar a resistência à ferrugem em cafeeiros portadores do gene S H3 e outros genes S H em Londrina, Paraná, Brasil. Foram avaliados vinte e um cafeeiros do CIFC com diferentes genes S H de resistência em condição de alta incidência natural em campo. Todos os cafeeiros avaliados portadores do gene S H3 apresentaram resistência à ferrugem. É possível que não existam raças de ferrugem com o gene de virulência v3 no Paraná. Plantas portadoras do gene S H3 em combinação com os genes S H5, S H6, S H7, S H8, S H9 e S H? seria muito importante para obter cultivares com resistência mais durável à ferrugem.

Selection for durable resistance to leaf rust using test-crosses on IAPAR-59 and Tupi IAC 1669-33 cultivars of Coffea arabica

The aim of this study was to identify plants of the IAPAR-59 and Tupi IAC 1669-33 coffee cultivars with less defeated resistance genes by the rust races present at IAPAR (Londrina, Paraná State, Brazil) using test-crosses. Eighteen test-crosses derived from hybridizations between 'IAPAR-59' or 'Tupi IAC 1669-33' with susceptible coffee to the rust disease were evaluated. Six hybrids were used as susceptible standards originated from hybridizations between two susceptible coffee plants. Many parental plants of the 'IAPAR-59' and 'Tupi IAC 1669-33' presented more defeated resistance genes against rust races present at IAPAR than others of these cultivars or the genes were in heterozygous, because of segregant susceptible plants observed in some test-crosses. The test-crosses were very efficient to identify plants with less defeated resistance genes to the H. vastatrix. Coffee plants considered resistants would must be made test-crosses to verify which plants presented less and/or more defeated genes in homozygous.

A ferrugem é uma das principais doenças do café. O objetivo deste trabalho foi identificar plantas das cultivares IAPAR-59 e Tupi IAC 1669-33 com menos genes de resistência quebrados às raças de ferrugem presentes no IAPAR (Londrina, Paraná, Brasil) através de cruzamentos testes. Foram avaliados 18 cruzamentos testes derivados dos cruzamentos de 'IAPAR-59' ou 'Tupi IAC 1669-33' com cafeeiros suscetíveis à ferrugem. Seis híbridos foram usados como testemunhas suscetíveis derivados do cruzamento de dois cafeeiros suscetíveis. Muitas plantas da 'IAPAR-59' e 'Tupi IAC 1669-33' apresentam mais genes de resistência quebrados pelas raças de ferrugem presentes no IAPAR do que outras dessas cultivares ou os genes estão em heterozigoze, pois foram observadas muitas plantas segregantes suscetíveis em alguns cruzamentos testes. Os cruzamentos testes são muito eficientes para selecionar plantas com menos genes de resistência à ferrugem quebrados. Em cafeeiros de cultivares considerados resistentes deveriam ser feitos cruzamentos testes para verificar quais plantas apresentam menos genes de resistência quebrados ou mais genes em homozigoze.