Tomatoes (Solanum lycopersicum L.) are the largest vegetable crop in the US by dollar value and represent a significant source of income for organic growers in the southeast. High tunnels allow growers to capture more profitable early markets, and the protection they offer provides additional benefits such as extended growing seasons and reduced leaf wetness/foliar disease. Most research on organic high tunnel tomatoes to date focuses on heirloom varieties due to their popularity among organic growers. However, advances in plant breeding in recent decades have yielded hybrids that combine the desirable culinary and aesthetic characteristics of heirlooms with the superior vigor and disease resistance of modern genetics. The objective of this study was to compare the performance and characteristics of such specialty hybrids under organic high tunnel, and organic and conventional field conditions in the Georgia Piedmont region. Two indeterminate cultivars were chosen for this project: ‘Estiva’, a mediterranean variety noted for setting fruit under high temperatures; and ‘Tomimaru Muchoo’, a Japanese pink slicer with thin skin and low acidity. Transplants of both varieties were grown under organic greenhouse conditions for several weeks before planting in organic field, organic high tunnel, or conventional field plasticulture systems. Data loggers were placed in each site to record temperature, relative humidity, PAR, and soil moisture. Fruits were harvested once per week and sorted by USDA marketability standards. Both total and marketable yield were recorded for each plot, as well as disease, pest, and physiological disorder damage. Subsampled fruits from each plot were measured for dimensions, mass, and qualitative aesthetic rating. Fruit and aboveground biomass samples from each plot were harvested, dried, and ground, then analyzed for elemental nutrient content. Soil samples were also taken from each plot prior to planting and after termination for nutrient analysis, pH, and organic matter. In 2023, the highest marketable yields were from the organic high tunnel, with ‘Estiva’ and ‘Tomimaru’ averaging 15491 and 15992 lb/A (FW), respectively; while the conventional field performed better in 2024, with average yields of 11807 (‘Estiva’) and 11611 lb/A (‘Tomimaru’). In 2024, ‘Estiva’ had substantial losses in the high tunnel due to blossom end rot, with 30% of the harvest being marketable as opposed to the 53% obtained from ‘Tomimaru’. These results suggest that under optimal conditions, organic growers can achieve similar yields of high-quality tomatoes to their conventional counterparts through proper application of high tunnels and superior varieties.
