TL;DR
The results show that the formulated consortium offers an innovative, stable, high quality, and environmentally friendly substitute to chemical fungicides for use in Integrated Disease Management (IDM) programs.
Moler disease caused by Fusarium acutatum represents a major constraint in shallot production. The use of biological control agents has emerged as an environmental friendly disease management. This study aimed to evaluate the effectiveness of a combined application of Trichoderma sp. and Bacillus velezensis B-27 in suppressing moler disease and to assess its effects on plant growth and yield of shallots. The study consisted of in vitro antagonistic assays and in vivo glasshouse experiments using two shallot varieties derived from botanical seeds or true shallot seed (TSS). The observed parameters included pathogen growth inhibition, disease intensity, number of bulbs, bulb diameter, fresh bulb weight, and dry bulb weight. The results demonstrated that the combined biological agents effectively inhibited pathogen growth and significantly reduced moler disease intensity. Although several yield-related parameters did not differ significantly among treatments, the application of biological agents showed considerable potential as an eco-friendly and sustainable approach for managing moler disease in shallot cultivation.
Pyricularia oryzae (syn. M. oryzae), the causative agent of blast disease, is among the most destructive fungal pathogens threatening rice production and other cereal crops worldwide. The search for environmentally sustainable alternatives to synthetic fungicides has increased interest in endophytic bacteria as potential biological control agents. In the current study, endophytic bacterial isolates obtained from disease-resilient finger millet were evaluated for their antagonistic activity against P. oryzae using dual-culture, cell-free culture filtrate, and conidial germination assays. Among the tested isolates, AL2 and AN6 exhibited the strongest antagonistic activity in dual culture, inhibiting mycelial growth by more than 82%, while AN2 showed moderate inhibition (52.07%). Cell-free culture filtrates suppressed fungal growth in a concentration-dependent manner across 10%-30% (v/v), with isolate AN6 demonstrating the highest inhibition of mycelial growth (85.24%) at a concentration of 30%, followed by AL2 and AN2. Similarly, the culture filtrates markedly reduced conidial germination after 12 h of incubation. At the highest concentration, AN6 reduced germination to 4.33%, followed by AL2 (6.33%) and AN2 (14.33%), compared with the untreated control. These findings identify finger millet-associated endophytes, particularly isolate AN6, as promising candidates for the biological management of rice blast disease. Further greenhouse and field evaluations are required to confirm their efficacy under natural conditions.
Relevance. Improving the efficiency of the pepper breeding process for resistance to fusarium wilt, caused by Fusarium verticillioides , requires studying the biological characteristics of the pathogen and the conditions for pathogenesis development according to the concept of the classical disease triangle. Taking these relationships into account is essential for developing reproducible and informative methods for evaluating breeding material. Purpose. To study the effect of temperature regime and nutrient medium composition on the vegetative growth of F. verticillioides , as well as to optimize key elements of the artificial inoculation protocol for accelerated evaluation of resistance in pepper breeding lines. Materials and methods. The study examined three F. verticillioides isolates with contrasting aggressiveness. The radial growth rate was assessed in vitro on PDA, OA, Czapek, and SNA media in the temperature range of 10-40 °C. Pathogenicity was tested in vivo on seedlings of five pepper lines at 25, 28, and 30°C. Additionally, two inoculation methods were compared: with mechanical stirring (orbital shaker, 100 rpm) and under static conditions. Results. Within the F. verticillioide s population, contrasting classes of pathogenicity were identified: highly aggressive (HA, 46%), moderately aggressive (MA, 27%), and weakly aggressive (WA, 27%). A direct correlation was established between the radial growth rate (VR) and aggressiveness: HA isolates grew 1,7-1,9 times faster than WA isolates (VR 13,0 vs. 7,6 mm/day). The temperature optimum for the growth of the highly aggressive isolate in vitro (VR 12,8 mm/day) and pathogenesis in vivo (I=3,4 points) coincided and was 28 °C. However, at 30°C, despite maintaining high growth in vitro (VR 10,3-11,8 mm/day), pathogenesis in vivo significantly decreased to 1,9 points. Two-way ANOVA showed that on day 7, the inoculation method (with shaker) accounted for 31,6% of the variance, while by day 14, the genotype dominated (40,6%). The use of an orbital shaker allowed accelerating pathogenesis and symptom manifestation, reducing the period of reliable evaluation from 14 to 7 days, which provided the opportunity for accelerated screening.Conclusion. Integration of knowledge about the biological characteristics of the pathogen into the experimental methodology allowed improving the elements of the artificial infection protocol. The use of these elements made it possible to significantly reduce screening time and increase the reliability of evaluating pepper resistance to fusarium wilt, which is important for accelerating the breeding process.
Groundnut (Arachis hypogaea L.), popularly known as peanut, is one of the most important oilseed and food legume crops cultivated worldwide. However, its cultivation is severely affected by stem rot disease caused by Sclerotium rolfsii, which leads to yield losses of up to 40%. The current study focuses on the management of Sclerotium rolfsii through the combined application of Trichoderma spp. and Bacillus spp. under field conditions. A roving survey conducted in major groundnut-growing areas of Trichy district, Tamil Nadu, revealed varying levels of disease incidence (46.00%–81.00%). The stem rot pathogen and antagonists were isolated from the surveyed locations and identified using morphological characteristics and molecular phylogenetic analyses based on ITS and 16S rDNA sequences, respectively. In vitro dual-plate assays revealed that Bacillus amyloliquefaciens BC-5 and Trichoderma harzianum TR-2 exhibited 82.22% and 86.66% inhibition, respectively, whereas paired-plate assays showed 78.27% and 75.55% inhibition against Sclerotium rolfsii. Scanning electron micrographs of Sclerotium rolfsii paired with effective Trichoderma and Bacillus isolates showed swollen hyphae with cell-wall damage, providing clear evidence of antagonistic interactions caused by volatile compounds produced by B. amyloliquefaciens and T. harzianum. At the field level, the combined application of effective B. amyloliquefaciens and T. harzianum performed better in reducing wilt disease incidence (77.90%) than the individual applications.
Meloidogyne incognita is one of the main phytonematodes affecting cotton productivity, requiring sustainable control alternatives to chemical nematicides. This study evaluated the efficacy of different bioinputs based on Bacillus velezensis BEIB-46 for the biological control of M. incognita and their effects on cotton development. The strain was identified through high-resolution genomic analyses, followed by production via submerged fermentation and formulation into four distinct forms: fermented broth (6 × 10⁸ CFU/mL), fermented broth supplemented with 10% composting extract (4 × 10⁸ CFU/mL), concentrated wet biomass of B. velezensis BEIB-46 (1 × 10 1 ⁰ CFU/g), and concentrated dry biomass of B. velezensis BEIB-46 (1 × 10 1 ⁰ CFU/g), applied at different doses at planting. After 98 days, the final nematode population, reproduction factor, control efficiency, and agronomic parameters were evaluated. All B. velezensis treatments significantly reduced the M. incognita population compared with the untreated control. The highest control efficiencies were observed for the concentrated formulations, particularly the dry solid form, which achieved up to 83.4% efficiency and reproduction factors of 0.4 and 0.3. In addition to nematode suppression, the treatments significantly increased fresh root mass and shoot dry mass, indicating a biostimulant effect. The concentrated dry formulations (2 and 5 g/ha) demonstrated superior performance by combining high nematicidal efficiency with root or shoot growth promotion, as well as improved commercial attributes and operational feasibility, highlighting the potential of B. velezensis BEIB-46 as a sustainable alternative for the management of M. incognita in cotton cultivation.
Stem-end rot (SER) is an important postharvest disease that reduces the quality and marketability of star apple (Chrysophyllum cainito L.), while biological control offers a more sustainable alternative to chemical management. This study aimed to (i) select fungal strains causing SER disease in star apple and (ii) select and appraise strains of Trichoderma spp. fungi as antagonists to the selected fungi causing SER disease under in vitro conditions. Ten fungal isolates were obtained from symptomatic fruits, and 35 Trichoderma isolates were recovered from star apple rhizosphere soils. Five rapidly growing fungal isolates were evaluated using a detached-fruit pathogenicity assay, with three fruits per treatment. The five strains with the strongest expression of SER were selected and identified as Lasiodiplodia theobromae L-SA01, L-SA03, and L-SA07, L. venezuelensis L-SA02, and L. egytiacae L-SA06. Among 25 Trichoderma isolates screened for extracellular enzyme activities, T-SA05, T-SA30, and T-SA32 were selected for broad antagonistic activity and were provisionally associated with T. asperellum, T. yunnanense, and T. viride, respectively. At 72 h, these isolates showed antagonistic efficiencies of 55.4–58.9% against L-SA01, 64.9–69.6% against L-SA02, 80.8–82.4% against L-SA03, 58.6–59.3% against L-SA06, and 49.9–54.1% against L-SA07. L. venezuelensis and L. egytiacae were the two fungal species first found to cause SER. T. yunnanense was recently proven to control the Lasiodiplodia spp. fungi that cause SER. The selected isolates also exhibited chitinase and glucanase activities, although their enzyme profiles did not fully correspond to their antagonistic efficiencies. These findings identify indigenous Trichoderma isolates for further taxonomic confirmation and evaluation in postharvest fruit assays.