Capsicum annuum L. is a significant horticulture crop known for its pungent varieties and used as a spice. The pungent character in the plant, known as capsaicinoid, has been discovered to have various health benefits. However, its production has been affected due to various exogenous stresses, including diseases caused by a soil-borne pathogen, Pythium spp. predominantly affecting the Capsicum plant in younger stages and causing damping-off, this pathogen can incite root rot in later plant growth stages. Due to the involvement of multiple Pythium spp. and their capability to disperse through various routes, their detection and diagnosis have become crucial. However, the quest for a point-of-care technology is still far from over. The use of an integrated approach with cultural and biological techniques for the management of Pythium spp. can be the best and most sustainable alternative to the traditionally used and hazardous chemical approach. The lack of race-specific resistance genes against Pythium spp. can be compensated with the candidate quantitative trait loci (QTL) genes in C. annuum L. This review will focus on the epidemiological factors playing a major role in disease spread, the currently available diagnostics in species identification, and the management strategies with a special emphasis on Pythium spp. causing damping-off and root rot in different cultivars of C. annuum L.

Fungal infections transmitted through the soil continue to pose a threat to a variety of horticultural and agricultural products, including tomato and chilli. The indiscriminate use of synthetic pesticides has resulted in a slew of unintended consequences for the surrounding ecosystem. To achieve sustainable productivity, experts have turned their attention to natural alternatives. Due to their biodegradability, varied mode of action, and minimal toxicity to non-target organisms, plant-derived protectants (PDPs) are being hailed as a superior replacement for plant pesticides. This review outlines PDPs’ critical functions (including formulations) in regulating soil-borne fungal diseases, keeping tomato and chilli pathogens in the spotlight. An in-depth examination of the impact of PDPs on pathogen activity will be a priority. Additionally, this review emphasises the advantages of the in silico approach over conventional approaches for screening plants’ secondary metabolites with target-specific fungicidal activity. Despite the recent advances in our understanding of the fungicidal capabilities of various PDPs, it is taking much longer for that information to be applied to commercially available pesticides. The restrictions to solving this issue can be lifted by breakthroughs in formulation technology, governmental support, and a willingness to pursue green alternatives among farmers and industries.

Gray mold disease caused by Botrytis cinerea is a damaging postharvest disease in tomato plants, and it is known to be a limiting factor in tomato production. This study aimed to evaluate antifungal activities of Vernonia amygdalina leaf extracts against B. cinerea and to screen the phytochemical compound in the crude extract that had the highest antifungal activity. In this study, crude extracts of hexane, dichloromethane, methanol, and water extracts with concentration levels at 100, 200, 300, 400, and 500 mg/mL were shown to significantly affect the inhibition of B. cinerea. Among the crude extracts, dichloromethane extract was shown to be the most potent in terms of antifungal activities. The SEM observation proved that the treatment altered the fungal morphology, which leads to fungal growth inhibition. For the in vivo bioassay, the fruits treated with dichloromethane extract at 400 and 500 mg/mL showed the lowest disease incidence with mild severity of infection. There were 23 chemical compounds identified in V. amygdalina dichloromethane extract using GCMS analysis. The top five major compounds were dominated by squalene (16.92%), phytol (15.05%), triacontane (11.31%), heptacosane (7.14%), and neophytadiene (6.28%). Some of these significant compounds possess high antifungal activities. This study proved that V. amygdalina from dichloromethane extract could be useful for inhibiting gray mold disease on tomato fruit and has potential as a natural antifungal agent.

Watermelon (Citrullus lanatus) cultivation is important for Malaysia's agricultural sector, accounting for approximately 8.8% of tropical fresh fruit production in 2021, primarily concentrated in Kelantan, Pahang, Johor, and Terengganu. Production dropped from 2016 to 2021, but showed resilience recently, bouncing back to 136 kilotonnes in 2022. Watermelon serves as a key export commodity, reaching markets in Singapore, China, and the Middle East. However, Fusarium wilt, caused by Fusarium oxysporum f.sp. niveum (Fon), poses significant challenges, resulting in yield losses ranging from 30% to 80%. The disease thrives in warm, moist climates and can persist in soil for years, posing a long-term threat to cultivation. Management strategies like using resistant crop varieties, rotating crops, and cultural practices are used, but chemical control is limited by environmental concerns and other restrictions. Continuous watermelon cultivation depletes soil nutrients and increases pathogen buildup due to the crop exhausting essential nutrients and promoting disease-causing organisms, thereby reducing soil health and crop yield. Plant growth-promoting rhizobacteria (PGPR) show promise in enhancing plant growth, suppressing pathogens, and improving soil sustainability. This study aims to evaluate the effectiveness of selected rhizobacteria species in promoting watermelon growth and suppressing Fusarium wilt in vitro. The tested rhizobacteria were identified as Pseudomonas atagonensis, P. resinovorans, P. germanica, P. alcaligenes, and P. glycinae. The production of fluorescence pigments was assessed using King's B medium and were detected in P. atagonensis and P. glycinae. The bacteria were further evaluated for their plant growth-promoting abilities, revealing that P. atagonensis, P. resinovorans, P. germanica, and P. glycinae exhibit nitrogen fixation, phosphate solubilization, and potassium solubilization activities. Fusarium wilt disease suppression was assessed via dual culture techniques by measuring the inhibition zone. Results indicated that P. atagonensis exhibited the highest inhibition zone (10 mm), followed by P. glycinae (5.3 mm) and P. alcaligenes (4 mm) compared to the control. Overall, this study suggests that Pseudomonas species can induce growth promotion and suppress Fusarium wilt disease in watermelon.

An eco-friendly microemulsion biofungicide derived from Allamanda cathartica was developed for the control of papaya anthracnose caused by Colletotrichum gloeosporioides. The formulation was prepared by blending surfactants, carrier oil, and water and optimized using ternary phase diagrams to identify stable microemulsion systems. All selected formulations exhibited surface tension values ranging from 29 to 31 mN/m, while particle sizes ranged from 51.79 to 1801.05 nm. The optimized formulation, coded as AM8, consisted of 35% Allamanda concentrated liquid crude extract (ACLCE), 26% water, 13% alkyl polyglucoside surfactant, and 26% dimethylamide oil. Papaya fruits coated with the formulations showed significant reductions (p < 0.05) in anthracnose incidence caused by C. gloeosporioides. Control fruits treated with water showed 75% disease incidence, whereas fruits treated with benomyl showed 42% disease incidence. Disease incidence, severity, and disease index decreased with increasing formulation concentration, and fruits treated with the eight formulations at 10% concentration exhibited significantly lower disease incidence (0–17%) and disease index (0–17%), with disease severity consistently scored as zero. The Allamanda formulation demonstrated strong antifungal activity with EC₅₀ and EC₉₅ values of 1.839 and 7.067 mg/mL (w/v), respectively, at the 95% confidence level. The optimized formulation AM8 remained stable for up to one year and showed superior disease control performance compared with the conventional fungicide benomyl. In addition, the formulation maintained fruit quality by preserving firmness, peel color, and soluble solids concentration, thereby extending papaya shelf life up to 30 days without adversely affecting the natural ripening process. These findings demonstrate the potential of Allamanda-based microemulsion formulations as sustainable biofungicides for postharvest control of papaya anthracnose and provide a promising alternative to conventional synthetic fungicides.

The use of soil beneficial bacteria, particularly plant growth-promoting rhizobacteria (PGPR), provides an eco-friendly alternative to synthetic agrochemicals in sustainable agriculture. This study aimed to isolate and characterize soil bacterial isolates from the rhizosphere of cabbage cultivation areas in Cameron Highlands, Malaysia, and evaluate their potential as PGPR and biocontrol agents. A total of 42 bacterial isolates were obtained, of which 15 were selected for detailed screening. Morphological and molecular characterization using 16S rDNA sequencing identified species from the genera Bacillus, Pseudomonas, and Serratia. These isolates exhibited key plant growth-promoting traits, including nitrogen fixation, phosphate solubilization, and potassium solubilization. Notably, isolates S9 and S30 demonstrated both plant growth-promoting and antibacterial activities against Xanthomonas campestris, a major pathogen of cabbage. Meanwhile, isolates S16 and S36, although lacking antibacterial activity, showed strong growth-promoting capabilities. These findings highlight the potential of native soil beneficial bacteria as biofertilizers and biocontrol agents, contributing to sustainable agricultural practices by reducing reliance on chemical fertilizers and pesticides. Future research should focus on field trials to validate their efficacy under diverse environmental conditions.