Hemileia Vastatrix Research Articles

New Varieties of Coffee: Compromising the Qualities of Adaptive Agroforestry? A Case Study From Southern Mexico

The most recent wave of coffee leaf rust, and its interaction with climatic variability, caused severe crop losses in shade-grown coffee areas in Latin America during the 2010–14 production cycles and beyond. Fungal attack on traditional Arabica varieties led to a process of substitution with new coffee varieties that are tolerant or resistant to the pathogen. The adaptation literature classifies this type of intervention as an incremental adaptation, with the potential to lead the system toward sustainable transformation. This research explores the initial consequences of introducing certain hybrid varieties into the transboundary area of the Tacaná Volcano, located between Chiapas and Guatemala, with the objective of identifying aspects that put the potential for adaptive agroforestry at risk. We hypothesize that the interaction of a range of economic, political, and ecological factors leads to ambiguous results in terms of both production and environmental adaptation. Ecological and management variables were analyzed in a case study of 30 producers. Quantitative data, collected through ecological plot sampling and application of a socio-productive survey, was complemented with ethnographic data. We conclude that, for our case study, the manner in which these new coffee varieties were introduced raises new sources of vulnerability that could be compromising the local and ecological benefits of agroforestry systems, as well as diminishing their capacity to cope with the future impacts of climate change.

Calcium and Potassium Nutrition Increases the Water Use Efficiency in Coffee: A Promising Strategy to Adapt to Climate Change

Coffee (Coffea spp.) represents one of the most important sources of income and goods for the agricultural sector in Central America, Colombia, and the Caribbean region. The sustainability of coffee production at the global and regional scale is under threat by climate change, with a major risk of losing near to 50% of today’s suitable area for coffee by 2050. Rain-fed coffee production dominates in the region, and under increasing climate variability and climate change impacts, these production areas are under threat due to air temperature increase and changes in rainfall patterns and volumes. Identification, evaluation, and implementation of adaptation strategies for growers to cope with climate variability and change impacts are relevant and high priority. Incremental adaptation strategies, including proper soil and water management, contribute to improved water use efficiency (WUE) and should be the first line of action to adapt the coffee crop to the changing growing conditions. This research’s objective was to evaluate at field level over five years the influence of fertilization with calcium (Ca+2) and potassium (K+) on WUE in two coffee arabica varieties: cv. Castillo and cv. Caturra. Castillo has resistance against coffee leaf rust (CLR) (Hemileia vastatrix Verkeley and Brome), while Caturra is not CLR-resistant. WUE was influenced by yield changes during the years by climate variability due to El Niño–ENSO conditions and CLR incidence. Application of Ca+2 and K+ improved the WUE under such variable conditions. The highest WUE values were obtained with an application of 100 kg CaO ha−1 year−1 and between 180 to 230 kg K2O ha−1 year−1. The results indicate that adequate nutrition with Ca+2 and K+ can improve WUE in the long-term, even underwater deficit conditions and after the substantial incidence. Hence, an optimum application of Ca+2 and K+ in rain-fed coffee plantations can be regarded as an effective strategy to adapt to climate variability and climate change.

English

Hemileia vastatrix is a fungus associated with coffee leaf rust, the most destructive disease of Coffea arabica. The objective of this work was to evaluate the antifungal activity of alcoholic extracts from roots of Baccharis salicina and to determine the metabolites present in these fractions. Antifungal activity was evaluated under in vitro conditions by monitoring the germination ability of H. vastatrix, the coffee leaf rust pathogen. In order to determine the presence of metabolites, chemical characterization of fractions obtained from methanolic root extracts was performed with help of an untargeted metabolomic approach and by using high-resolution mass spectrometry (MS) and MS2 based on direct-injection electrospray mass spectrometry (DIESI-MS) and hierarchical cluster analysis (HCA). Germination percentage was evaluated by leaves fixation technique. The MEBs significantly decreased the percentage of germination of H. vastatrix to levels below 5% as the dose increased. The multivariable analysis confirmed that the distribution of three fractions of methanolic extracts belonged to polyketides, organoheterocyclic compounds, fatty acyls, prenol-lipids, organo-oxygen and farnesene classes. This report comprises the first study of the metabolomic profile and biological activity study of roots from B. salicina against coffee leaf rust pathogen H. vastatrix. © 2021 Friends Science Publishers

Current status of plant pathogens of agricultural importance for Colombia. A review

Plant disease still plays a major role in limiting agricultural production worldwide. Pathogens and pests reduce crop yield and can cause large reductions in crop quality. Colombia is no exception as it contends with many devastating pathogens that present a major threat to the country’s agricultural sector. This review is important because it highlights four of the more damaging pathogens that affect the economics of important crops in Colombia - Xanthomonas phaseoli pv. manihotis (Xpm), Fusarium oxysporum f. sp. cubense (Foc), Phytophthora palmivora, and Hemileia vastatrix. This paper was based on an extensive literature search for plant diseases in Colombia in databases such as PubMed and Google Scholar. Moreover, this search was complemented with research on crop production in the country in databases made available by the Food and Agriculture Organization of the United Nations (FAO). The four pathogens reviewed in this paper were chosen not only because of their current devastating effects on Colombia’s agricultural production but also because of their potential to cause further damage in the near future. Understanding the current situation of these crop pathogens in Colombia is imperative for state directives aimed at developing informed and efficient control strategies.

Current status on coffee leaf rust (hemileia vastatrix) in sidama and gedeo zone, southern Ethiopia

Coffee is the most important and second traded commodity next to oil in the world. In Ethiopia, coffee leaf rust caused by Hemileia vastatrix is one of the third most economically important diseases of Coffee Arabica. The current status of coffee leaf rust was intensively assessed and examined in 189 sample coffee farms from six districts across major coffee growing areas of the Southern Ethiopia. At each farm, ten randomly selected trees on a diagonal transect across the farm were assessed for disease incidence and severity. The survey data showed that coffee leaf rust was present in all assessed district varying in magnitude and extent of damage. The highest overall mean of rust incidence (38.6%) and severity (13.80%) was recorded at Dilla zuria while the lowest incidence (10.52%) and severity (1.38%) was at Yergachaffee district. The highest altitude range was obtained at Yergachaffee (1838-2056) while the lowest was at Dilla zuria (1434-1825) district. Overall mean severity and incidence result indicate that, there was statistical (p = 0.058 for severity, p = 0.044 for incidence) and negative correlation between intensity and altitude (severity, r= -0.80 and incidence, r= -0.82). The linear regression equation of severity and incidence obtained from the data was Y= -0.036X+73.16 and Y = -0.074X +158.9 (where Y= percentage CLR severity and incidence, respectively and X= altitude). This regression equation implies that, in higher elevation areas the rust intensity was low as compare to the lower elevation. Finally, the disease was remarkably increasing from time to time in all assessed coffee farms. Therefore, appropriate measurement like farmers’ awareness creation and training on how to control disease as well as appropriate agronomic managements has to be seriously undertaken. In addition, development of coffee leaf rust resistant varieties to southern Ethiopia through resistant breeding has to be set high priority.

Towards smallholder food and water security: Climate variability in the context of multiple livelihood hazards in Nicaragua

• We develop a framework and case study for jointly assessing household food and water security in a multi-hazard environment. • Water insecurity and food insecurity are positively related across households, even after controlling for household characteristics. • In 2017, a drought ended, contributing to improved food and water security, but adverse agrifood price risks persist. • Higher incomes, larger farm areas, and diversified farm production are correlated with improved food and water security. • Climate risks should be assessed within the context of interactions with other hazards and changing terms of access. Climate variability and change affect both food and water security, as do other hazards, such as shifting food prices, plant pathogens, and political economic changes. Although household food and water insecurity affect billions, most studies analyze them separately. This article develops a relational approach to explaining household access to food and water in a multi-hazard context. We identify pathways linking hazards to livelihood vulnerability and assess the relative importance of climate-related hazards. Analyzing longitudinal data collected from two surveys of the same 311 smallholder households in northern Nicaragua, conducted in 2014 and again in 2017, we find that peak seasons of food and water stress are asynchronous across the agricultural calendar, resulting in a total of five to six months of food and/or water stress. Across households, we find a significant positive relationship between water and food insecurity, even after adjusting for household fixed effects. Households experienced less food and water insecurity in 2017 than in 2014, due in part to the end of a severe drought in 2016, but remained concerned about damage from a severe coffee leaf rust outbreak and unfavorable agrifood prices that reduce income and threaten food security. Higher incomes and larger farm areas correlated with improved food and water security. We propose a generalizable approach for the joint assessment of household food and water security, which foregrounds the influence of seasonality and climate variability in the context of multiple hazards. This approach and our findings can contribute to developing integrated risk reduction strategies, building resilient livelihoods, and informing policy changes and partnerships with organized smallholders to improve resource access and sovereignty.

Stability of Arabica coffee genotype (Coffea arabica L.) against leaf rust (Hemileia vastatrix)

Coffee is now experiencing a serious threat from fungus Hemileia vastatrix which caused epidemic of rust disease in America, Africa, and Asia. As solution, the use of resistant cultivars is the best way. However, interaction between genotype and environment can change the rank of genotypes that shows instability of these genotypes against leaf rust. Purpose of this research was to study stability of genotypes of Arabica coffee against coffee leaf rust. A field experiment was arranged as factorial randomized complete block design with 2 factors (genotypes and climate zones) with three replication. The observed parameters were branch rust incidence, leaf rust incidence, and leaf rust severity. This research result showed significant genotype x environment interaction in all variables. Length of dry season is the most important factor affecting coffee leaf rust because it had the highest correlation coefficient with leaf rust severity (r = 0.662**). Less length of dry season should be the first criteria for selection of coffee farms. The most desired genotype was G7 which performed low leaf rust severity (7.71%) and had a stable resistance indicated by the same leaf rust severity in all environments and 6 SMg. Due to the significant interaction between genotypes and the environment, the genotype to be planted in a region must be tested in that region first.

Efektivitas Minyak Cengkeh, Nimba dan Kemiri Sunan, serta Ekstrak Babadotan Terhadap Penyakit Karat Daun Kopi (Hemileia vastatrix)

<p><em>Leaf rust disease </em>(Hemileia vastatrix)<em> is commonly controlled using synthetic fungicides. Plant oils and extracts are expected to reduce the pathogen. The research aimed to determine the effectiveness of clove, </em>Reutealis trisperma<em>, </em><em>and neem oils, and </em>Ageratum conyzoides<em> extract against </em>H. vastatrix<em>. The study was conducted in the laboratory and greenhouse of the Indonesian Industrial and </em><em>Beverage Crops Research Institute and smallholder coffee plantation in Garut, West Java, from January to December 2018. </em>The A. conyzoides<em> were extracted in the laboratories. Plant oils and extract's effectiveness</em><em> was tested in vitro against the germination of urediniospore and in a greenhouse to inhibit disease development. The in vitro experiment were evaluated the eight concentrations of extract and oil were: 0 (steril water), 250, 500, 1000, 1500, 3000, and 5000 ppm. Whereas, in the greenhouse experiments used three concentrations of 1000, 2500, and 5000 ppm of the extract and oil, and 2000 ppm of Mankozeb (positive control). The greenhouse test was carried out on Arabica coffee plants, completely randomized design and five replications. The number of spots, disease intensity, and plant growth were examined periodically. The results showed that all of the the extract and oil inhibited the urediniospores germination, and the most effective concentrations were 500 ppm, 3000 ppm, and 5000 ppm. </em>A. conyzoides<em> extract, and clove oil effectively suppressed the infection of </em>H. vastatrix<em> by 75.99% and 64.00%, respectively, and comparable to the synthetic fungicide (68.00%).</em></p>

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.

Elucidating the interactions between the rust Hemileia vastatrix and a Calonectria mycoparasite and the coffee plant

SummaryCalonectria hemileiae, a fungus associated with pustules of the coffee leaf rust (CLR, Hemileia vastatrix) in Brazil, was tested in vitro and in planta to assess its biocontrol potential. The fungus inhibited the germination of rust spores by over 80%. CLR severity was reduced by 93% when Calonectria was applied to coffee leaf discs inoculated with H. vastatrix, whilst a reduction of 70-90% was obtained for in planta experiments. Mycoparasitism was demonstrated through the fulfillment of Koch's postulates. Elucidation of the biochemical interaction between Calonectria and Hemileia on coffee plants indicated that the mycoparasite was able to increase plant resistance to rust infection. Coffee plants sprayed with Calonectria alone showed greater levels of chitinase, β-1,3-glucanase, ascorbate peroxidase and peroxidase. Although effective in controlling the rust, fungicide applications damaged coffee photosynthesis, whereas no harm was caused by Calonectria. We conclude that C. hemileiae shows promise as a biocontrol agent of CLR.

Capillary electrophoresis as a tool for genotyping SH3 mediated coffee leaf rust resistance

Coffee is an important agricultural commodity in the world. However, it is susceptible to Hemileia vastatrix (Hv), an obligatory biotrophic fungus that causes coffee leaf rust (CLR). Natural resistance to rust has been identified in the wild species Coffea canephora and Coffea liberica. These species have been used in breeding programs where interspecific resistant hybrids have been generated. The SH3 gene, derived from C. liberica, has been shown to confer extreme and long-lasting resistance to Hv. A total of 167 accessions of the INIA’s Coffee Germplasm Collection of Peru (INIA-CGC) were screened with 4 markers linked to the SH3 gene. As positive controls, EA67 (C. liberica) and the hybrid S.288 (C. arabica x C. liberica) were used. Separation of PCR products was done by capillary electrophoresis, which allow to discriminate the alleles of each marker. For three markers, specific alleles for either C. arabica or C. liberica species were found. In all cases, S.288 exhibited specific alleles for both species; whereas the INIA-CGC accessions had exclusively C. arabica alleles and EA67 had C. liberica alleles. The BA-48-21O-f marker did not produce PCR fragments for any of the positive controls, suggesting that this marker is not as predictive as the other three to determine the presence of SH3. This work reports the existence of multiple alleles for the Sat244 marker; however, the collection does not have the SH3 mediated-resistance gene. Finally, the utility of capillary electrophoresis as a tool to identify alleles linked to SH3 was demonstrated.

New species and records of Trichoderma isolated as mycoparasites and endophytes from cultivated and wild coffee in Africa

A survey for species of the genus Trichoderma occurring as endophytes of Coffea, and as mycoparasites of coffee rusts (Hemileia), was undertaken in Africa; concentrating on Cameroon and Ethiopia. Ninety-four isolates of Trichoderma were obtained during this study: 76 as endophytes of healthy leaves, stems and berries and, 18 directly from colonized rust pustules. A phylogenetic analysis of all isolates used a combination of three genes: translation elongation factor-1α (tef1), rpb2 and cal for selected isolates. GCPSR criteria were used for the recognition of species; supported by morphological and cultural characters. The results reveal a previously unrecorded diversity of Trichoderma species endophytic in both wild and cultivated Coffea, and mycoparasitic on Hemileia rusts. Sixteen species were delimited, including four novel taxa which are described herein: T. botryosum, T. caeruloviride, T. lentissimum and T. pseudopyramidale. Two of these new species, T. botryosum and T. pseudopyramidale, constituted over 60% of the total isolations, predominantly from wild C. arabica in Ethiopian cloud forest. In sharp contrast, not a single isolate of Trichoderma was obtained using the same isolation protocol during a survey of coffee in four Brazilian states, suggesting the existence of a ‘Trichoderma void’ in the endophyte mycobiota of coffee outside of Africa. The potential use of these African Trichoderma isolates in classical biological control, either as endophytic bodyguards—to protect coffee plants from Hemileia vastatrix, the fungus causing coffee leaf rust (CLR)—or to reduce its impact through mycoparasitism, is discussed, with reference to the on-going CLR crisis in Central America.

The urea transporter DUR3 is differentially regulated by abiotic and biotic stresses in coffee plants.

The high costs of N fertilizers in the coffee production emphasizes the need to optimize fertilization practices and improve nitrogen use efficiency. Urea is widespread in nature, characterizing itself as a significant source of nitrogen for the growth and development of several organisms. Thus, the characterization of genes involved in urea transport in coffee plants is an important research topic for the sustainable production of this valuable cash crop. In the current study, we evaluated the expression of the DUR3 gene under abiotic and biotic stresses in coffee plants. Here, we show that the expression of a high-affinity urea transporter gene (CaDUR3) was up-regulated by N starvation in leaves and roots of two out of three C. arabica cultivars examined. Moreover, the CaDUR3 gene was differentially expressed in coffee plants under different abiotic and biotic stresses. In plants of cv. IAPAR59, CaDUR3 showed an increased expression in leaves after exposure to water deficit and heat stress, while it was downregulated in plants under salinity. Upon infection with H. vastatrix (coffee rust), the CaDUR3 was markedly up-regulated at the beginning of the infection process in the disease susceptible Catuaí Vermelho 99 in comparison with the resistant cultivar. These results indicate that besides urea acquisition and N-remobilization, CaDUR3 gene may be closely involved in the response to various stresses.

Temporal dynamics and biocontrol potential of a hyperparasite on coffee leaf rust across a landscape in Arabica coffee’s native range

Agroforestry systems can provide habitats for a rich biodiversity including multitrophic interactions, which presents opportunities to develop natural pest control. Shade coffee systems in several coffee growing areas of the world host such unique habitats where pests and their natural enemies interact. One of the major global challenges for coffee production, coffee leaf rust caused by the fungal pathogen Hemileia vastatrix is attacked by the fungal hyperparasite, Lecanicillium lecanii. However, we lack insights in the dynamics and biocontrol potential of the hyperparasite on coffee leaf rust from landscapes in Arabica coffee’s native range. To understand the temporal dynamics across landscapes and environmental drivers of the rust and hyperparasite, and the potential for biocontrol of the rust by the hyperparasite, we studied the rust and hyperparasite during the dry and wet seasons for three consecutive years at 60 sites across a gradient of coffee management in southwestern Ethiopia. We found that coffee leaf rust was more severe during the dry season, whereas the hyperparasite was more severe during the wet season in two out of three years. The rust growth rate from the wet to the dry season transition was negatively related to the hyperparasite index during the wet season, implying a potential top-down control. Coffee leaf rust was generally more severe at lower altitudes in the dry season, whereas the hyperparasite was more severe at high altitude. The rust incidence increased with management intensity, while the hyperparasite was more common under less intensive management. This study could be interesting in that it represents a landscape where Arabica coffee originated and the rust and hyperparasite might have a long co-evolutionary history. Our findings highlight the potential of the hyperparasite to suppress the rust’s growth rate from the wet to dry season transition when the rust severity could otherwise be at its peak. We show that less intensively managed landscapes with dense shade levels are likely to increase hyperparasite abundance and result in an improved top-down control of the rust. However, more detailed knowledge is needed on the interaction of these species to assess its importance for reducing rust induced yield losses or the risk of rust outbreaks.

Efecto Bioprotector de Micorrizas Arbusculares en la Reducción de Roya (Hemileia vastatrix) en la Región San Martín

La roya es un problema generalizado que ha afectado a diferentes países de América Latina, generando pérdidas económicas en los productores cafetaleros. Se evaluó el efecto de los hongos micorrízicos arbusculares (HMA), sobre la presencia de roya (Hemileia vastatrix) en plantas de café. Se empleó un Diseño Completamente al Azar con dos factores: fuentes de inóculo HMA e Inoculación de roya, incluyendo tratamiento testigos (absoluto e infestado); se usó como sustrato tierra agrícola y arena (2:1); se inoculó plantas de café con 1 500 esporas de HMA procedente de Rioja, Lamas, Dorado y Huallaga, posteriormente se inóculo con esporas de roya; se evaluaron altura de planta, área foliar, biomasa seca y aérea, incidencia, severidad, colonización micorrízica y longitud de micelio extraradical. Los resultados mostraron que los tratamientos inoculados con HMA presentaron mejoras incrementos en morfología, micorrización y menor incidencia y severidad a roya.

A fungus-eat-fungus world: Digitopodium, with particular reference to mycoparasites of the coffee leaf rust, Hemileia vastatrix

Digitopodium hemileiae was described originally in 1930 as Cladosporium hemileiae; growing as a mycoparasite of the coffee leaf rust (CLR), Hemileia vastatrix, in a sample of diseased leaves of Coffea canephora collected in the Democratic Republic of Congo. No cultures from this material exist. More recently, the type material was re-examined and, based on morphological features, considered to be incorrectly placed in Cladosporium. The new genus Digitopodium was erected to accommodate this species. Interest in fungal antagonists of H. vastarix, as potential biocontrol agents of CLR, led to comprehensive surveys for mycoparasites, both in the African centre of origin of the rust, as well as in its South American exotic range. Among the rust specimens from Ethiopia, one was found to be colonized by a fungus congeneric with, and similar to, D. hemileiae. Pure cultures obtained from the Ethiopian material enabled a molecular study and for its phylogenetic position to be elucidated, based on DNA sequence data from the ITS and LSU regions. Molecular data showed that two members of the recently erected genus Hyalocladosporiella (Herpotrichiellaceae: Chaetothyriales) are congeneric with Digitopodium from Ethiopia and morphologically similar to both D. hemileiae and the two Ethiopian isolates. These isolates were found to be morphologically and genetically identical to H. tectonae, described previously from Brazil. Thus, species of Hyalocladosporiella are re-allocated to Digitopodium here; including D. tectonae, and a novel species, D. canescens, recently found in Brazil growing as a mycoparasite of Puccinia thaliae. The potential use of D. hemileiae and D. tectonae for classical biological control of CLR is discussed.

Estimation of Genetic Variability, Heritability and Genetic Advance of Some Wollega Coffee (<i>Coffea arabica</i> L.) Landrace in Western Ethiopia Using Quantitative Traits

Arabica coffee is the predominant commodity in contributing for foreign exchange in Ethiopia and improvement for yield and other desirable traits is highly momentous. Estimating genetic diversity is a prerequisite activity in plant breeding program for crop improvement. This study was designed to determine the extent of genetic variability among Wollega coffee landrace and importance of gene revealed in traits. The 26 genotypes were tested during the 2016/2017 cropping season at Mugi and Haru sub- enters using RCBD. The combined analysis manifested significant difference among genotypes only in node number per primary branch (NNPB), fruit traits and Coffee leaf rust (CLR) although significant difference recorded for 18 and 22 of the 23 traits at Haru and at Mugi, respectively. The difference between environments was significant for all traits, except for CLR, yield (YLD), leaf, some fruit and bean traits. Performance at Haru was less than at Mugi for all traits showed significant difference. Genotype x environment (GEI) was significant for all traits excluding NNPB, leaf length (LL), fruit width and CLR indicating inconsistency performance of Coffee genotypes. At Haru, high phenotypic coefficient of variation (PCV>20%) recorded for YLD (25.5%), CLR (110.0%) and number of secondary branch (NSB) (22.0%), but High genotypic coefficient of variation (GCV>20%) recorded only for CLR (99.6%). At Mugi, High PCV and GCV (>20%) recorded for YLD (38.6%) and CLR (98.4%). Heritability ranged from 10.0% (YLD) to 88.0% (BW) while genetic advance (GAM) ranged from 1.5% (LL) to 32.4% (NSB) at Haru. At Mugi, Heritability ranged between 31% (CLR) and 84.0% (bean thickness) and between 3.3% (LL) and 44.0% (YLD) for GAM. The present results elucidate the existence of moderate genetic diversity among genotypes for some traits at individual location indicating the possibility of improvement for desired traits via selection. For further diversity analysis, molecular characterization methods need to be carried out.

Evaluation of Tepi and Its Surrounding Coffee Collections Against Major Coffee Diseases at Gera and Tepi

Coffee has for centuries played an important role in the Ethiopian economy and represents the main cash crop cultivated by small-scale farmers for social, economic, political and ecological sustainability. The estimated coffee production area in Ethiopia is 561,761 ha. In Ethiopia, coffee berry disease (CBD), coffee wilt disease (CWD) and coffee leaf rust (CLR) are foremost factors in reducing the quantity and quality of coffee in the country. developing disease resistant landrace coffee varieties and boost the yield with their intrinsic cup quality, a multidisciplinary research program has been designed and implemented at Jimma agricultural research center. To meet this objectives, local land race development program of Tepi 88 coffee collections were started in 2015 and 108 coffee accessions were collected and planted in 2016 at Tepi and Gera research sub centre by Jimma Agricultural Research Center. so, 88 coffee accessions were evaluated for their resistance using visual assessment, attached berry test to CBD, visual to scores CLR and laboratory inoculation test to CWD. There were significant differences among the Tepi coffee collections tested for resistance to coffee berry disease. The range was from 0% (T-83/2011) – 98% (T-63/2011) most of Tepi coffee accessions show susceptable reaction for CBD but most of the accessions show resistance reaction at Gera. Coffee collections were also evaluated for their resistance to coffee leaf rust under field condition at Tepi research center. Highly significant difference among coffee cultivars in percent coffee leaf rust severity was observed (Table 1). Coffee leaf rust disease percent severity varied between 0.17% (T-41/2011) – 21.7% (T-11/2011). There existed highly significant difference among cultivars both in percent wilt seedlings death and incubation period). Disease severity and incubation period on Tepi coffee collections varied between 9.33% (T-06/2011) –97.3% (T-21/2011) and 132 -10 days respectively. Based on over all detailed analysis of field evaluation and greenhouse test investigation for major diseases, and their Yield potentials, Nine Tepi coffee accessions were promoted to Variety verification.

Factors influencing the performance of phosphites on the control of coffee leaf rust

ABSTRACT This study investigated the effect of different phosphites on the control of coffee leaf rust (CLR) caused by Hemileia vastatrix, considered the major disease affecting coffee yield worldwide. Three-month-old coffee plants were sprayed with two doses each of the phosphite solutions (standar., and double), as follows: K (40% P2O5; 1.., and 3 mL∙L-1), K (30% P2O5; ., and 6 mL∙L-1), Cu (2.., and 5 mL∙L-1), Mn+Zn (., and 6 mL∙L-1., and Na (., and 6 mL∙L-1) 24 h before being inoculated with H. vastatrix. Leaves were not washed or washed with deionized water after the foliar phosphites spray. Plants sprayed with water served as the control treatment. Inoculation was performed on the abaxial side of the first pair of expanded leaves using a camel hairbrush with a suspension of urediniospores (1 mg per leaf). All phosphites applied at the standard doses (from 1.5 to 3 mL∙L-1) reduced the total number of pustules (TNP) per leaf by 28-69% regardless of washing treatment. The biggest reductions were observed for Cu phosphite, which decreased the TNP per leaf by 6., and 69% withou., and with leaf washing, respectively. A similar trend was observed when the double doses of phosphites (from 3 to 6 mL∙L-1) were used, though Na phosphite without leaf washin., and Mn/Zn phosphite withou., and with leaf washing were not efficient to reduce the TNP per leaf. Without leaf washing, only C., and Na phosphites decreased CLR severity at the standard doses (53-61%), whereas all phosphites, except the Mn/Zn phosphite, reduced CLR severity at the double dose. The CLR severity was decreased using K 30%, K 40., and Cu phosphites when applied at the standard doses with leaf washing (41-59%). With double doses, only C., and Na phosphites decreased CLR severity by 55% for both treatments. In conclusion, the efficiency of the phosphites for CLR control varied according to the accompanying cation, dos., and washing conditions. The Cu phosphite resulted in the best CLR control regardless of the dose use., and the washing conditions.

Mathematical modelling and optimal control of the seasonal coffee leaf rust propagation

Abstract This paper deals with the problem of modelling and optimal control of the coffee leaf rust (CLR) in a coffee plantation. We first formulate and analyze a mathematical model for the propagation of CLR with impulsive effect, which represents the non-production period of coffee. Then, the CLR control is formulated and solved as an optimal control, showing how a biological control strategy can be implemented in a coffee plantation to reduce the damage caused by CLR, therefore increasing the coffee production. Numerical simulations are performed to illustrate and validate the theoretical results.