Arif Wibowo

Fungal resistance against Quinone outside inhibitors (QoI) fungicides has been a long-standing concern amidst numerous efforts to protect agricultural production. An allele-specific cytochrome b gene-based polymerase chain reaction (PCR) using cDNA has been developed to unveil G143A mutation leading to QoI resistance in Colletotrichum gloeosporioides but the possibility of detecting the mutation in other members of Cg species complex yet to be clarified. Bioassay assessments including mycelial growth, conidial germination, and germ tube length inhibition tests on four mango-isolated C. asianum and four citrus-isolated C. gloeosporioides showed partial resistance only on the C. asianum HM_IJB isolate. Direct sequencing on the cytochrome b region determined all eight isolates lacked G143A mutation. However, HM_IJB isolate demonstrated F129L mutation that had been reported to confine a low-level resistance to QOI fungicides. Moreover, the F129L substitution was caused by a TTA SNP, which has never been observed in Colletotrichum asianum. The allele-specific PCR and restriction fragment length polymorphism PCR were further deployed to confirm that there was no G143A mutation in the eight tested isolates thus indicated that these approaches also applicable to detect resistance profile of C. asianum.

Praktik budidaya yang intensif pada tumpang gilir antara cabai rawit–jagung perlu dilakukan evaluasi untuk mengetahui keunggulan lahan dan kompetisi di antara dua spesies yang berbeda. Tujuan penelitian ini untuk mengetahui nilai kompetisi dan keunggulan lahan dari model tanam tumpang gilir cabai rawit–jagung dan aplikasi agens hayati. Penelitian dilakukan di Magelang, Jawa Tengah, Indonesia pada Mei 2019–Januari 2020. Penelitian menggunakan metode penelitian kuantitatif yang disusun dalam Rancangan Acak Kelompok Lengkap dua faktor; faktor pertama yaitu model tanam tumpang gilir (2 baris dan 3 baris cabai rawit) dan faktor kedua yaitu aplikasi agens hayati (dengan dan tanpa aplikasi agens hayati). Monokultur cabai dan jagung tanpa aplikasi agensi hayati merupakan kontrol. Data dianalisis menggunakan Analisis Varians dan Uji Lanjut Duncan's multiple range tests pada α = 5%. Tumpang gilir dinilai berdasarkan Nisbah Kesetaraan Lahan, Nisbah Kesetaraan Lahan berdasarkan Waktu, Agresivitas, Rasio Kompetisi, dan Kehilangan Hasil Aktual. Hasil penelitian menunjukkan bahwa Model tanam 2 dan 3 baris cabai rawit pada pola tanam tumpang gilir cabai rawit dengan jagung dan pemberian agens hayati menghasilkan nilai Nisbah Kesetaraan Lahan dan Nisbah Kesetaraan Lahan Berdasarkan Waktu > 1. Cabai rawit memilki indeks Agresivitas dan Rasio Kompetisi yang lebih besar daripada jagung, namun memiliki nilai Kehilangan Hasil Aktual yang tinggi jika ditanam pada pola tumpang gilir tidak disertai pemberian agens hayati. Dari metode yang diterapkan pada penelitian ini, maka tumpang gilir cabai rawit dengan jagung model 2 baris dengan pemberian agens hayati direkomendasikan karena layak diterapkan dan menguntungkan untuk diusahakan terutama bagi pertanian skala kecil.

Bananas are one of the five most important food commodities in the world. In Indonesia, banana production is mostly for domestic consumption, featuring a wide variety of cultivars. In contrast, the global market is dominated by a single cultivar, largely supplied by the world’s biggest banana exporter, Ecuador, followed by Guatemala and Costa Rica. Initially, the global banana market depended on a single cultivar, Gros Michel, for around 60 years, but the first outbreak of Panama disease (race 1 of Fusarium oxysporum f. sp. cubense) led to its destruction. More recently, the Cavendish, which is the global banana clone, was ravaged by the second pandemic of Panama disease caused by Fusarium oxysporum f. sp. cubense Tropical Race 4. This problem severely impacted Indonesia’s banana industries; however, a few national banana industries have survived and have expanded their planting area over the past five years. This review will discuss the identification, ecology, and interaction of the pathogen and the host plant, epidemiology, and management of Panama disease in Indonesia. While Gros Michel, Cavendish, and other banana cultivars are easily found at local markets in Indonesia, the spread of Panama disease of Fusarium oxysporum f. sp. cubense Tropical Race 4 began pandemically 20 years ago, and this section discusses the pandemic epidemiology of the disease. Different identification tools were applied, and diversity of Fusarium oxysporum f. sp. cubense Tropical Race 4 was found in Indonesia. Panama disease management in Indonesia varies based on the local wisdom of the farmer groups or the industry. However, in response to the outbreaks, in 2002, the Indonesian government formed the National Task Force for Banana Wilt Disease Management under the Directorate of Horticultural Plant Protection in the Indonesian Department of Agriculture during the pandemic period of banana wilts, including Fusarium oxysporum f. sp. cubense Tropical Race 4 and banana blood disease.

Dieback disease in mango trees has been observed in Indonesia, particularly in Java Island, with the causal agent remaining unidentified. One of the important pathogens that are responsible for causing mango dieback is Colletotrichum. Field surveys were conducted in various mango cultivating areas in Java Island, Indonesia to assess prevalence of Colletotrichum as dieback disease pathogen. Eleven Colletotrichum isolates were recovered from symptomatic dieback twigs and morphologically characterized. Genetic diversity fingerprint analysis was carried out using rep-PCR. Phylogenetic analysis identified isolates as belonging to Colletotrichum asianum and Colletotrichum cairnsense using partial sequences of four gene regions, including ITS, ACT, GAPDH, and TUB2. Pathogenicity tests on mango seedlings cv. Arumanis showed that all fungal isolates were responsible for causing dieback symptoms. Subsequently, symptomatic tissue was reisolated to fulfill Koch’s Postulate. This study represented new funding for two species of Colletotrichum causing mango dieback in Indonesia.

Kurniasari I, Wibowo A, Subandiyah S, Pattison AB. 2024. Association of soil bacterial diversity and composition with Fusarium wilt disease of bananas in Yogyakarta Province, Indonesia. Biodiversitas 25: 2264-2275. Infection of banana plants with Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc-TR4) leads to a cascade of changes in the rhizosphere, resulting in changes to the soil physicochemical properties and bacterial community composition. This study aimed to determine the core taxa associated with different soil physicochemical properties and disease statuses and to identify the factors exerting the greatest influence on the soil bacterial community composition of bananas in Special Region of Yogyakarta Province, Indonesia. Rhizospheric soil from healthy and infected plants was collected from four banana locations, including Kulon Progo, Gunungkidul, Bantul, and Sleman districts, at 10-30 cm depth between May and September 2021. Laboratory analysis was conducted for soil physicochemical properties, and the abundance of Foc-TR4 was undertaken. Additionally, 16S rRNA gene-based metagenomics analysis was used to quantify bacterial diversity in all samples. Soil type significantly influenced the abundance and composition of the bacterial community more than disease status did. Contrarily, disease status groups influenced the complexity of bacterial network interaction more than soil type. Actinobacteriota, Proteobacteria, Chloroflexi, Acidobacteriota, and Bacteriodota are the major phyla associated with all soils. This study identified 60 bacterial genera as core members of the banana rhizosphere. These core bacterial genera include various plant growth-promoting bacteria involved in nitrogen fixation, phytohormone production, siderophore production, and biocontrol mechanisms for producing antifungal compounds. Our work provides a basis for future research on the soil bacterial composition associated with banana plants to enhance plant health against Fusarium wilt disease.

Shallot (Allium cepa var. aggregatum.) is a horticultural plant that is widely consumed in the world. However, the productivity of shallots in Indonesia is still relatively low, if compared to the actual optimum production potential of shallot. Shallot cultivation in Indonesia often experiences many problems. One of the problems is twisted diseases caused by Fusarium sp. This research aimed to study the effect of the application of organic material enriched with Bacillus in suppressing the development of twisted disease of shallot. This study was arranged in Randomized Complete Block Design (RCBD) with 5 treatments namely (A) compost + Bacillus velezensis isolate B-27, (B) compost + Bacillus cereus isolate RC76, (C) B. velezensis isolate B-27+B. cereus isolate RC76+compost, (D) compost + Trichoderma asperellum and (E) control (compost 1 ton/ha) with 5 replications on glasshouse treatment and 3 replications on field treatment. The results showed that the combination of B. velezensis in compost effectively reduced the incidence of twisted disease, the number of Fusarium spp. colonies, and the number of infected bulbs by Fusarium sp. Besides, the combination of compost with microbial agents showed better results than compost single treatment.

Twisted disease (Fusarium spp.) is an endemic disease that reduces shallot production in the coastal land area of Samas, Bantul, Yogyakarta. The application of Bacillus spp. can suppress the twisted disease by secreting secondary metabolites and enhancing soil suppressiveness. This study aimed to determine the effectiveness of adding spraying Bacillus spp. on the disease incidence, production of shallots, and their effect on the diversity of rhizomicrobiome by culture microbe approaches. Bacillus spp. with a density 10⁸ cfu mL^-1, Trichoderma asperellum 10⁶ cfu mL^-1 was applied by spraying to the shallot. Fungicide chlorothalonil, propiconazole, and prochloraz were used to control the disease. The diversity of rhizobacteria and fungi was analyzed using the ribosomal intergenic spacer analysis (RISA) method. Based on the analysis result, the addition of spraying B. velezensis B-27, combination B. velezensis B-27 and B. cereus RC76, and T. asperellum was unable to enhance the suppression of twisted disease, but it was able to enhance the production of shallot bulbs reaching 7.10, 7.80, and 8.43 ton ha^-1. Furthermore, the result revealed the diversity of the rhizomicrobiome, spraying Bacillus sp. showed 39% differences in bacterial diversity with control while T. asperellum caused 43% difference in the diversity. Spraying Bacillus spp. has not been able to suppress the incidence of twisted diseases compared to control. However, the similar disease incidence on a spraying Bacillus spp. and control showed a higher production until 70% compared to control. This result showed that the addition of spraying Bacillus spp. able to increase the tolerance of shallot plants toward twisted disease.

Phytopythium vexans isolated from potatoes rhizospher in Ngablak, Magelang, Central Java was reported having a potency to cause potato tuber rot in in vitro test. Some fungicides had been intensively applied in this area to control potato late blight even using sublethal dose. This study investigated resistance response of the pathogen against several fungicides which were Mancozeb, Dimethomorph, mixture of Mancozeb and Mefenoxam, and mixture of Oxathiapiprolin and Famoxadone. The experiment was conducted to observe the sensitivity response of pathogen against those fungicide and the experiment repeated with one of the isolates which growth in sublethal concentration to observe the resistance response. Both experiment data was analyzed by Probit Analysis. On sentivity test, data showed that P. vexans were insensitive against Dimethomorph, but it was sensitive against Mancozeb, mixture of Mancozeb and Mefenoxam, as well as mixture of Oxathiapiprolin and Famoxadone. On Mancozeb treatment, mycelia were inhibited 100% at the sugested concentration. However, at the sublethal concentration the mycelial collony grew abnormally. Pathogen isolate from the sublethal concentration were used as material for the resistance response study. The effect of the sublethal application of Mancozeb to P. vexans caused resistance to Mancozeb itself and cross resistance against Dimetomorph and mixture of Oxathiapiprolin and Famoxadone. It was proven by higher value of predicted EC50 and EC95 on the second experiment compared to the predicted EC50 and EC95 from the first one. The resistant P. vexans isolate was able to produce sporangium and chlamydospore.

Pisang abaka (Musa textilis) merupakan penghasil serat alam berkualitas tinggi dengan permasalahan utama penyakit layu fusarium oleh Fusarium oxysporum f. sp. cubense TR4. Penelitian ini bertujuan memperoleh bakteri pelarut silika (BPS), menentukan pengaruh aplikasi BPS dan pupuk silika untuk menghambat serangan fusarium serta memacu pertumbuhan tanaman pisang. Sebanyak enam isolat BPS diperoleh dari tanah rizosfer pisang abaka sehat, tiga di antaranya memiliki aktivitas antagonis terhadap F. oxysporum f. sp. cubense TR4. Empat perlakuan yang dicobakan menunjukkan keparahan penyakit layu fusarium yang tidak berbeda. Demikian juga keempat perlakuan tidak menunjukkan perbedaan pada peubah pertumbuhan yang diamati. Bakteri pelarut silika dan pupuk silika belum mampu mengendalikan F. oxysporum f. sp. cubense TR4. Oleh karena itu, pisang abaka terbukti rentan terhadap F. oxysporum f. sp. cubense TR4.