Suwandi Suwandi

Humid-tropical Ultisols supporting smallholder horticulture in Southeast Asia are widely recognised as degraded agroecosystems whose biogeochemical functioning has been disrupted by accelerated cation leaching, sulfur depletion following reduced atmospheric S deposition, and decades of...

Between 2024 and 2025, a stem canker disease outbreak, causing wilt and sudden death, was observed in Syzygium myrtifolium plantations in South Sumatra, Indonesia, with mortality rates reaching 50%. Our observations revealed the formation of stem cankers, cracked bark, and black lesions within the sapwood and heartwood. These symptoms were accompanied by partial to total foliage wilting, ultimately leading to plant death. Multilocus phylogenetic analysis using combined ITS and EF1-α gene sequences confirmed Ceratocystis fimbriata as the causal agent of this novel canker and wilt disease in S. myrtifolium. All pathogenic strains exhibited high virulence on S. myrtifolium seedlings during nursery inoculation trials to fulfill Koch’s postulates. Host range pathogenicity tests demonstrated high susceptibility in Artocarpus heterophyllus and Acacia mangium, both showing 100% mortality with lesion lengths of 8.05–9.2 cm and 1.5–1.7 cm, respectively. Conversely, weak pathogenicity was observed in Annona muricata, which exhibited a 20% mortality rate and lesion lengths of 3.2–3.6 cm. This study represents the first report of C. fimbriata as the causal agent of sudden death and stem canker in S. myrtifolium in Indonesia and globally.

This study examines the effectiveness of Ganoderma sp. in decomposing lignin in herbaceous plants. The study was conducted in a greenhouse at the Faculty of Agriculture, Sriwijaya University, with temperatures ranging from 28-30oC and humidity reaching 70-80%. The test plants consisted of uwi (Dioscorea alata) and talas (Colocasia esculenta), and oil palm seedlings were used as a comparison. The parameters observed included the level of decay and mycelium viability after inoculation. The results showed that the highest level of decay occurred in taro, reaching 65.22% in sterilized soil and 52.56% in unsterilized soil, while uwi experienced decay of 33.9% and 33.03%. The viability of Ganoderma sp. mycelium remained high (>70%) in all treatments. This indicates a strong ability to adapt to various environmental conditions. Thus, the study shows that the ligninase activity of Ganoderma sp. contributes significantly to decomposition without reducing the viability of the Ganoderma sp.

Ganoderma boninense, the causal agent of basal stem rot (BSR), poses a significant threat to oil palm plantations, resulting in severe economic losses and limited effective control options. This study investigates the antifungal properties of root exudates from three cultivars of cardamom (Elettaria cardamomum) as a sustainable alternative for BSR management. Root exudates were collected from eight cardamom samples and tested in vitro against G. boninense at concentrations of 1.25%, 5%, and 20% using malt extract agar (MEA) medium. Fungal growth inhibition was assessed by measuring colony diameter and electrical conductivity (EC) to evaluate membrane integrity. All exudate samples exhibited varying degrees of antifungal activity, with maximum inhibition across the tested concentrations ranging from 13.4% to 39.5%. The degree of inhibition depended on both the sample and concentration of the exudate, with no clear correlation between cultivar origin and antifungal efficacy. Increased EC values in treated media suggest that the inhibition mechanism involves hyphal membrane damage. This study is the first to report the antifungal activity of cardamom root exudates against G. boninense, highlighting their potential as natural agents for sustainable disease management in oil palm plantations.

Shallot is a high value horticultural crop valued for its flavor, aroma, and medicinal properties, and is rich in phenolics and flavonoids that contribute to antioxidant activity. Limited dryland and fluctuating demand in South Sumatra highlight the need for alternative systems such as floating cultivation. This study aimed to evaluate the effects of different ammonium sulfate (ZA) doses on the bulb yield, total phenolic, and flavonoid contents of Bauji shallots grown under floating cultivation. The experiment used a randomized complete block design with three replications and four ZA fertilizer treatments (0, 60, 180, and 360 kg ha⁻¹). Observed variables included total phenolic and flavonoid contents measured by spectrophotometry and dry bulb weight. The results indicated that the ZA application significantly increased dry bulb weight and total phenolic content but did not affect flavonoids. The highest bulb yield and flavonoid content were obtained with 60 kg ha⁻¹, whereas phenolics peaked under the control (0 kg ha⁻¹), suggesting a trade-off between yield and secondary metabolite accumulation. Correlation analysis revealed a positive association between bulb weight and flavonoid content, whereas phenolics were negatively related to fertilizer input. As the first report on Bauji shallots under floating cultivation, these findings indicate that moderate ZA fertilization (60 kg ha⁻¹) optimizes bulb yield while maintaining bioactive compound levels. However, further multi-season studies are needed for broader recommendations.

Karlina L, Suwandi S, Fadli R, Muslim A, Hamidson H, Irsan C. 2025. Metabolomic profiling and antifungal potential of turmeric (Curcuma longa) root exudate against Ganoderma boninense. Biodiversitas 26: 3600-3609. Ganoderma boninense, the causative agent of basal stem rot, significantly threatens oil palm cultivation. Turmeric (Curcuma longa) is a potential source of antifungal compounds for agricultural applications. This study investigates the antifungal properties of root exudates from four turmeric ecotypes (Palembang, Bandung, Surabaya, and Bangka) against Ganoderma boninense and employs untargeted metabolomics using LC-HRMS. The root exudates were collected from two-month-old plants grown in soil by incubating the roots in aerated sterile distilled water for 12 hours. The exudates were then filter-sterilized and directly used for antifungal assays and metabolomic analysis. The results revealed that turmeric root exudates at concentrations of 1.25%, 5%, and 20% inhibited G. boninense growth in a concentration-dependent manner, with the efficacy varying depending on turmeric ecotypes. The Palembang ecotype exhibited the strongest antifungal activity, with inhibition rates of 37.7% to 46.7%. The Bandung and Surabaya ecotypes showed moderate inhibition (10.3-36.2%), while the Bangka ecotype had weak effects. None of the turmeric exudates at concentrations between 1.25% and 20% promoted the growth of G. boninense. Metabolomic profiling played a crucial role in this study, identifying 193 metabolites, with 20 significant differentially accumulated metabolites in the inhibitory exudate group. Key metabolites such as azelaic acid, bis(2-ethylhexyl) phthalate, haplofungin C, menthyl acetate, and piptamine were identified, shedding light on their potential contribution to antifungal activity. These findings indicate that turmeric root exudates contain bioactive compounds that could be explored as eco-friendly biocontrol agents against G. boninense.

Community Service in IoT-Based Organik Rice Farming Assistance, conducted through demonstration plots. The goal is to address productivity issues in rice farming on floodplain swamp lands. This issue can be addressed by applying a sustainable farming approach that combines technology with organic materials. The activities held with the Tunas Baru farmer group in Kotadaro Village have shown positive results. The group’s 27.5-hectare land, which had low productivity in the second season, has shown improvement due to increased soil fertility and a significant reduction in pest and disease attacks below harmful economic thresholds. The technology used in this program includes pH monitoring sensors, and NPK content sensors, among others. Additionally, the program teaches the production of soil conditioners such as biocompost, liquid Beauveria, and liquid Trichoderma. Over 83% of the farmer group members involved in the program understand the long-term benefits and the potential for increased productivity due to the adoption of sustainable farming practices with a technological approach.

Pratama R, Suwandi S, Muslim A, Mulawarman. 2025. Diversity of Ceratocystis fimbriata causing canker and wilt disease on Cupressus sempervirens (Italian cypress) in Indonesia. Biodiversitas 26: 278-287. In 2022-2023, new diseases were observed on Cupressus sempervirens in South Sumatra, Indonesia, with the disease incidence increasing from 17.6% to 26.5% in 2023. Initial symptoms, included stem cankers, black lesions on sapwood and vascular tissue, discoloration and partial wilting of leaves, and eventual complete drying, leading to plant death. The objective of this study was to isolate and identify the fungal pathogen causing wilt disease in C. sempervirens trees using morphological characterization and DNA sequencing. In 2022-2023, a disease survey was conducted in six districts of South Sumatra. The results showed that six out of ten locations were infected, with disease incidence ranging from 4.1% to 17.6% in 2022, increasing to 2% to 26.5% in 2023. Pathogen identification employed a polyphasic approach, combining morphological and molecular characteristics from specific genomic regions (the internal transcribed spacer (ITS) and ?-tubulin). Both the morphological features (including a globose base with a long neck-ended tip with ostiolar hyphae, cylindrical conidia, and hat-shaped ascospores) and phylogenetic analysis identified the isolates as Ceratocystis fimbriata. ITS gene sequences indicated that all the isolates belonged to the ITS5 haplotype. In pathogenicity test, pathogen caused mortality in C. sempervirens, Acacia mangium, and Artocarpus heterophyllus plants. The implications of these findings are significant, as they can potentially lead to the development of effective control measures. To our knowledge, this is the first report of Ceratocystis spp. causing wilt disease on C. sempervirens in South Sumatra.

Basal stem rot (BSR) caused by Ganoderma boninense threatens the oil palm industry, particularly in Southeast Asia. This study evaluated methanol extracts of turmeric rhizome (TRE) from four ecotypes (Bangka, Bandung, Palembang, and Surabaya) for antifungal activity against G. boninense. TRE showed strong inhibition, with a minimum inhibitory concentration (MIC) of 0.31% and IC50 values between 0.93% and 1.92%, exhibiting dose-dependent effects. Treated fungal hyphae displayed morphological abnormalities with enhanced chitin and protein deposition. Elevated electrical conductivity in fungal culture media indicated membrane damage and leakage of intracellular contents. These findings highlight the potential of TRE as a sustainable alternative to chemical fungicides for BSR management.

Antraknosa yang disebabkan oleh jamur Coletotrichum spp. merupakan penyakit utama yang merugikan produksi cabai di Indonesia. Trichoderma spp. merupakan agensia biocontrol yang menghasilkan metabolit antifungi pada biakan cair. Penelitian bertujuan untuk menguji efikasi biakan cair Trichoderma spp. dalam menghambat menghancurkan konidia C. capsici serta efikasi menekan penyakit antraknosa. Tiga jenis media cair yaitu Y (0,5% ragi + 2% sukrosa), T (0,5% tanin + 2% sukrosa), dan YT (0,5% ragi + 0.5% tanin + 2% sukrosa) diinokulasi dengan campuran 3 isolat Trichoderma dan diinkubasi selama 14 hari pada 150 rpm. Biakan cair diujikan pada konsentrasi 0,2%; 1%; and 5% terhadap konidia C. capsici. Biakan cair juga diberikan sebagai perlakuan perendaman buah cabai, sebelum, bersamaan, dan setelah inokulasi C. capsici untuk menguji efikasinya terhadap perkembangan bercak antraknosa. Hasil penelitian menunjukkan paparan selama 12 jam biakan cair Trichoderma spp. menyebabkan konidia C. capsici mengalami lisis sebesar 70,9-94,3%. Perlakuan biakan cair sebelum, bersamaan dan setelah inokulasi patogen menghambat perkembangan bercak antraknosa sampai 51,4% dibandingkan kontrol, terutama pada media YT.