Screening coffee genotypes for Cercospora coffeicola resistance in Brazil

Several efforts have been made by many researchers worldwide to develop coffee plants resistant to different Cercospora species; however, studies concerning C. coffeicola , specifically, are still incipient. In the present study, a blend of strains from this pathogen was inoculated into 18 Brazilian commercial cultivars, a coffee clone of Arabica, as well as into 41 accessions from the Germplasm Collection of Minas Gerais, to evaluate the genetic resistance ability within the population and select superior genotypes for the breeding program. After predicting genotypic values of the evaluated material, the most efficient way to select genotypes based on the data of severity to brown eye spot (BES) was also examined. Moreover, the action of defense mechanisms against C. coffeicola attacks was investigated by assessing the levels of total soluble phenolic compounds and soluble lignin in contrasting genotypes regarding disease susceptibility. Based on the results, the accession MG 1207 Sumatra demonstrated an intrinsic genetic capacity to maintain low levels of severity to brown eye spot. This genotype can thus substantially contribute to the development of new cultivars, which may lead to reduced use of pesticides. This study also evidenced that four evaluations of severity is enough to reach accuracy and efficiency for the severity of BES, thus providing expressive genetic gains. Finally, it is suggested that the levels of lignin and phenolic compounds are not associated with the resistance of coffee genotypes to brown eye spot.

Deteksi Penyakit Brown Eye Spot pada Daun Kopi Menggunakan Metode Euclidean Distance dan Hough Transform

Pengolahan citra digital memiliki manfaat yang bisa digunakan dalam lingkup yang beragam, salah satunya dalam lingkungan perkebunan kopi. Dengan memanfaatkan pengolahan citra, citra daun yang didapat dalam perkebunan kopi, bisa diketahui jenis kopi beserta penyakit yang diderita. Untuk mengetahui jenis daun akan menggunakan metode euclidean distance, dimana daun yang digunakan sebagai objek penelitian merupakan daun kopi robusta dan daun kopi arabika. Untuk penyakit pada daun kopi terdapat berbagai macam, namun penyakit yang digunakan sebagai objek penelitian hanyalah penyakit brown eye spot. Pendeteksian penyakit dilakukan menggunakan metode hough transform, dikarenakan metode ini dapat digunakan untuk mendeteksi lingkaran yang merupakan gejala dari penyakit brown eye spot . Tujuan dalam penelitian ini yaitu untuk menganalisa keefektifan dari metode yang digunakan, yang pertama yaitu tingkat akurasi euclidean distance untuk mendeteksi daun uji coba antara daun kopi arabika dan daun kopi robusta. Metode yang kedua menganalisa tingkat keefektifan tingkat akurasi dalam pendeteksian penyakit brown eye spot pada daun uji coba menggunakan hough transform. Uji coba dilakukan terhadap 7 daun kopi arabika dan 4 daun kopi robusta menggunakan Matlab R2017a, dimana hasil tidak terjadi kekeliruan terhadap pendeteksian tehrhadap daun uji coba, ketujuh daun kopi arabika dikenali sebagai daun kopi arabika, dan keempat daun kopi robusta dikenali sebagai daun kopi robusta. Pada metode kedua untuk pendeteksian penyakit brown eye spot pada daun uji coba didapatkan keakurasian pada daun arabika sebesar 55% dan untuk daun kopi robusta sebesar 50%.

PHIALOMYCES MACROSPORUS REDUCES CERCOSPORA COFFEICOLA SURVIVAL ON SYMPTOMATIC COFFEE LEAVES

<p>Saprobe fungi and necrotrophic pathogens share the same niche within crop stubble and the search for fungi non-pathogenic to plants that are able to displace the plant pathogens from its overwintering substrate contributes to the disease management. Brown eye spot (<em>Cercospora coffeicola</em>) is among the most important coffee diseases, it is caused by a necrotrophic pathogen that has decaying leaves as its major source of inoculum. We have screened saprobe fungi for the ability to reduce <em>C. coffeicola</em> sporulation and viability and determined the possible mechanisms involved in the observed biocontrol. A selected saprobe fungus, <em>Phialomyces macrosporus</em>, reduced the pathogen’s viability by 40% both <em>in vitro</em> and <em>in vivo</em>. The fungus acts through antibiosis and competition for nutrients. It produced both volatile and non-volatile compounds that inhibited <em>C. coffeicola</em> growth, sporulation, and viability. It also produced the tissue maceration enzyme (polygalacturonase), which reduces the pathogen both in detached leaves or in planta. The reduction in the fungal viability either by the saprobe fungus or its polygalacturonase-fraction supernatant resulted in the reduction of the disease rate. Therefore, <em>P. macrosporus </em>is a potential microbial agent that can be used in an integrated management of brown eye spot through the reduction of the initial inoculum of the pathogen that survives and builds up in infected leaves.</p><p> </p>

Difference between isolates from brown eye spot and black spot lesions in coffee plants

The objective of this work was to evaluate the difference between the isolates from two cercospora leaf spot symptoms (brown eye spot and black spot) in relation to conidial morphology, mycelial growth, cercosporin production, and reproduction of symptoms in coffee leaves collected in three municipalities in the state of Minas Gerais, Brazil. There was a difference between the isolates for the studied variables, but without any relation to the type of symptom. The differences found were not associated with the origin of the isolates. The symptoms characterized as black spot were associated with different host conditions during the infection process.

Agronomic performance and adaptability of arabic coffee resistant. To leaf rust in the central brasilian savanna

Breeding programs and later indication of rust resistant cultivars for different environments and crops systems, in the concept of diseases integrated control, reach out for productivity raising and reduced production costs. The aim of this work was to evaluate the agronomic performance and adaptability of new <em> Coffea arabica </em> cultivars and progenies resistant to leaf rust in Central Brazilian Savanna. The experiment has been conducted since 2008 in an experimental area of Embrapa Hortaliças. Twenty three resistant cultivars, four progenies and three susceptible cultivars as controls, were assessed in a complete randomized block design with four replicates. The following traits were analyzed: plant height, stem diameter, canopy projection, number of plagiotropic branches, yield, grains percentage retained in sieves above 17, grain ripening and diseases resistance. Catucaí 2SL, Sacramento and Araponga stood out in vegetative growth. The highest yields are observed for IPR 103, Obatã 1669-20, Palma II, Sabiá 398 and Acauã, with values higher than 60 sacks per hectare. Among all these cultivars is observed high resistance to rust leaf and greater susceptibility to brown eye spot in the cultivar Acauã, for the place and period of evaluation.

PENGAMATAN BEBERAPA PENYAKIT yang MENYERANG TANAMAN KOPI (Coffea sp) di DESA MEKAR JAYA KECAMATAN BETARA KABUPATEN TANJUNG JABUNG BARAT

The research about the observation of diseases that attack Coffee plants (Coffea sp.) in Mekar Jaya village Betara subdistrict Tanjung Jabung Barat Regency, and Agriculture Quarantine Laboratory Jambi had been done for six months. The aim of this research is to identification the disease that attack coffee plants. The research was conducted by observing the disease which in coffea plants area, and identificaton pathogenic fungi in laboratory by moist chamber method using microscop and also fungi identifications book. The result of this research showed that there were three pathogenic fungies which attack Coffee plants namely: 1) Hemileia sp wich caused coffee leaft rust disease, 2) Cercospora coffeicola wich caused Brown eye-spot disease, and 3) Upasia salmanicolor wich caused Upas fungi disease. Keywords : Pathogenic fungi, Cooffee Plants Disease, Coffee Plants. AbstrakPenelitian tentang pengamatan beberapa penyakit yang menyerang tanaman Kopi (Coffea sp) di desa Mekar Jaya kecamatan Betara kabupaten Tanjung Jabung Barat dan di Laboratorium Karantina Pertanian Jambi telah dilakukan selama 6 bulan. Tujuan penelitian adalah untuk mengetahui penyakit yang menyerang tanaman kopi. Penelitian dilakukan dengan mengamati gejala penyakit di lapangan dan mengidentifikasi jamur patogen di laboratorium secara moist chamber dengan menggunakan mikroskop dan buku identifikasi jamur. Hasil penelitian menunjukkan bahwa ditemukan tiga jamur patogen yang menyerang tanaman kopi yaitu: 1) . Hemileia sp penyebab penyakit Karat Daun 2) Cercospora coffeicola penyebab penyakit Bercak Daun, 3) Upasia salmanicolor penyebab penyakit Jamur upas. Kata Kunci : Jamur Patogen, Penyakit tanaman kopi, Tanaman kopi