Heat stress is one of the production constraints for tomato (Solanum lycopersicum L.) due to unfavorable, above optimum temperatures. This research was undertaken to evaluate growth and fruit yield of tomato genotypes under three contrasting growing conditions (i.e., optimal temperature in field-, high temperature in field- and high temperature in greenhouse conditions) to determine their relative heat tolerance. Eleven tomato genotypes, including two local check varieties, were evaluated, and data on growth and yield were measured and analyzed. The interactions between the genotypes and growing conditions for all yield traits were significant. In general, the performance of tomato under optimal temperature field conditions was better than under high temperature field- and greenhouse conditions. Genotypes CLN1621L, CLN2026D, CLN3212C, and KK1 had consistently greater fruit yield per plant in all growing conditions. Although the local genotype, Neang Tamm, had lower yield under optimal conditions, it performed moderately well under high temperature field- and high temperature greenhouse conditions, and yield decrease under high temperature condition was minimal. Genotype CLN1621L had stable fruit setting compared to other genotypes under high temperature conditions. Since fruit setting and yield are important traits for heat tolerance, genotypes CLN1621L and Neang Tamm are potential candidates for breeding programs focused on improved yield and heat stress tolerance.

Red-fleshed dragon fruit (Hylocereus polyrhizus) is commonly cultivated in Thailand, especially in southern Thailand, where the weather favors plant growth and development. In 2021, stem canker of H. polyrhizus was observed in a dragon fruit plantation field in Phatthalung Province, southern Thailand. Small, orange circular spots developed on the stem of H. polyrhizus, which later became gray, and the lesion expanded with a mass of conidia. Scytalidium-like fungus was isolated from infected tissues. Based on morphology and phylogenetic analyses of internal transcribed spacer (ITS), nuclear large subunit (LSU) and β-tubulin (tub) sequences of fungal isolates, the fungus was identified as Neoscytalidium dimidiatum. Pathogenicity tests revealed that this isolate caused stem canker on the stem of H. polyrhizus, similar to that observed in the field. Knowledge of the diagnosis of plant diseases is an important step for managing plant diseases and therefore, this finding provides basic information for the development of appropriate strategies to manage stem canker disease on H. polyrhizus plants.

Stem canker on dragon fruit caused by Neoscytalidium dimidiatum causes severe losses in production of this fruit worldwide. Biological control by Trichoderma species is widely used to control several plant diseases. However, environmental conditions affect the use of biocontrol agents in the field. The development of a new formulation may offer an alternative way to address the problem of stem canker on dragon fruit caused by N. dimidiatum. In this study, we sought to develop a Trichoderma asperelloides PSU-P1 formulation that would be effective against N. dimidiatum. Three vegetable oils, two emulsifier-dispersing agents (Tween 20 and Tween 80), and one source of carbon (dextrose) were tested for carrier additives. We assessed the viability and antifungal ability of formulations incubated at ambient temperature and at 10 °C during a storage period of 1–6 months. The formulation composed of coconut oil, DW, and tween 20 in a ratio of 30:60:10 required a mixing time of 1.14 min; this was significantly faster than the mixing times of other formulations. Application of this formulation suppressed canker development; a canker area of 0.53 cm² was recorded, compared with a control (pathogen only) area of 1.65 cm². In terms of viability, this formulation stored at ambient temperature showed a surface area percentage of T. asperelloides PSU-P1 ranging from 64.43 to 75.7%; the corresponding range for the formulation stored at cool temperature was 70.59–75.6%. For both formulations, percentage inhibition gradually decreased from 1 to 6 months, with ranges of 59.21–77% and 60.65–76.19% for formulations incubated at ambient and cool temperatures, respectively. Our findings suggest that the formulation developed in this study prolongs the viability of T. asperelloides PSU-P1 conidia by up to 6 months, effectively inhibits N. dimidiatum in vitro, and reduces stem canker in vivo.