Genotypic and phenotypic correlations among coffee leaf rust symptoms of Arabica coffee genotypes in North Sumatra. Indonesia

Coffee leaf rust (CLR) is a pandemic and a serious threat for coffee sustainability in many coffee producing countries. To overcome this CLR, the world’s consensus is to use of resistant cultivars which can be created through coffee breeding program. This research aimed to study genotypic and phenotypic correlations between CLR symptoms of seven arabica coffee (Coffea arabica L.) genotypes that were selected from different districts of North Sumatra Province, Indonesia. This experimental research using a randomized complete block design with three replications was conducted at the experimental garden of the Faculty of Agriculture, Universitas HKBP Nommensen in Medan. The result of this study indicate that leaf rust severity (LRS) had a genotypic component variance of 86.8% which indicated that LRS was controlled more dominantly by plant genetics than other unknown factors. Severity indicated by LRS showed no genotypic and phenotypic correlation with dispersal indicated by branch rust incidence (BRI) and leaf rust incidence (LRI). BRI genotypically correlated with LRI. The results of this study could contribute to resistance coffee breeding for CLR.

Paisagens vulneráveis do café: uma história global de agências humanas e não humanas

Resenha de: MCCOOK, Stuart. Coffee is Not Forever: A Global History of Coffee Leaf Rust. Athens: Ohio University Press, 2019. 306 p.

Coffee Leaf Rust (Hemileia vastatrix) in Kenya—A Review

Coffee is one of the most important cash crops and beverages in the world. Production of coffee is limited by many factors, which include insect pests and diseases, among others. One of the most devastating coffee diseases in many coffee-producing countries is Coffee Leaf Rust caused by the fungus Hemileia vastatrix. Kenya is a coffee-producing country and has conducted studies to understand and manage the disease. Management strategies for the disease include the development and use of fungicide spray programs, cultural control practices, breeding resistant coffee varieties, and biological control agents. This paper reviews the status of the disease and management options applied in Kenya.

Phylogenetic relationship of coffee leaf rust in the central jungle of Peru

Coffee leaf rust is the main disease that causes significant losses in Coffea arabica. In Peru, this disease caused epidemics between 2008 and 2013 with production losses of 35 %. The objective was to identify H. vastatrix using a morphological and molecular approach based on a phylogenetic species concept. Coffee leaf samples with symptoms of chlorotic lesions with the presence of yellow uredospores at different severity stages of different cultivars were collected from 11 locations in the departments of Pasco and Junin during 2017-2018. DNA was purified as proposed by Cristancho and coworkers. The major subunit of ribosomal DNA was amplified with universal primers LR0R and LR5, and sequenced by Macrogen and deposited in GenBank. Sequences from the genera Achrotelium, Blastospora, Cystopsora, Hemileia, and Mikronegeria were included for phylogenetic analysis. The results showed that the rust was distributed in coffee growing regions of Pasco: Villa Rica (Catimor, Caturra, and Gran Colombia); Oxapampa (Yellow Caturra), and Junín: San Luis de Shuaro (Catimor), Chanchamayo (Catimor), San Ramón (Catimor), Vitoc (Caturra), Pichanaki (Caturra), Río Negro (Caturra), Pangoa (Yellow Caturra, Gran Colombia, Limani). It was also grouped into a single clade with isolated H. vastatrix from Mexico and Australia, suggesting that they come from a common ancestor. This is the first confirmed report using molecular barcoding of H. vastatrix in the central jungle of Peru.

Strategies for Coffee Leaf Rust Management in Organic Crop Systems

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.

Potential of the Dithiocarbimate Fungicides on the Control of Coffee Leaf Rust and Asian Soybean Rust

Coffee leaf rust (Hemileia vastatrix) and Asian soybean rust (Phakopsora pachyrhizi) are diseases that cause great losses in the productivity of these crops, not only in Brazil but on a global scale. Coffee and soybean varieties grown are susceptible to these diseases. Thus, it is necessary to search for efficient compounds for their chemical control, mainly from the group of protectors or residuals so that they can be formulated with systemic fungicides to control the diseases. This allows not only the efficient management of diseases but also the prevention of the emergence of resistant mutants in the populations of these pathogens. In this context, the present study aimed to evaluate the sensitivity and effect of bis(N-R-sulfonyldithiocarbimato)zincate(II) salts fungicides on the epidemiological components of pathosystems coffee × H. vastatrix and soybean × P. pachyrhizi. Initially, four zinc(II) complexes salts (1A, 2A, 1B, and 2B) with N-R-sulfonyldithiocarbimates were synthesized. In the first experiment, the in vitro sensitivity of H. vastatrix and P. pachyrhizi was studied for the four compounds synthesized and mancozeb at 0.5, 5.0, 50.0, 100.0 and 200.0 µmol L-1. All the compounds synthetized in this study had inhibitory effects on H. vastatrix and P. pachyrhizi. In the greenhouse it was studied the effect of bis(N-R-sulfonyldithiocarbimato)zincate(II) salts on the epidemiological components of coffee leaf rust and Asian soybean rust. For the pathosystem coffee × H. vastatrix, there were no differences in the values obtained for the bis(N-R-sulfonyldithiocarbimato)zincate(II) salts and mancozeb for the latent period. For the sporulated lesion variable, the control treatment had a mean value of 149.0 lesions/leaf, differing significantly from the other treatments. The mean value of compound 2B was estimated as 25.0 lesions/leaf, differing significantly from treatments 1A, 1B, 2B, and mancozeb. Treatments 1A, 1B, 2B, and mancozeb did not differ significantly from each other. For the Asian soybean rust, the area under the disease progress curve had a mean value of 75.8 for the control, while for the 2A treatment the value was 4.1, differing from the other compounds. The treatments 1A, 1B, 2A, and mancozeb did not differ significantly from each other. In conclusion, compounds 1A, 2A, and 1B were more efficient in the control of the coffee leaf rust, while compound 2A was efficient in the control of the Asian soybean rust.