Late summer organic tomato production with heat tolerant tomato cultivars

Field production of organic fresh-market tomatoes in the U.S. Desert Southwest is desired by local producers and consumers. Tomato yield and fruit quality can be seriously impacted by heat stress (HS) and beet curly top virus (BCTV) infection of the main-season crop. We examined delayed planting of HS tolerant cultivars as a strategy for avoiding and mitigating these abiotic and biotic stressors. In 2016, seven putative HS tolerant cultivars, and one considered to be heat susceptible, were transplanted to the field in mid-summer to avoid peak populations of beet leafhopper (Circulifer tenellus), the vector of BCTV. In 2017, seven HS tolerant cultivars, one heatsusceptible, and two hot-set hybrid cultivars were transplanted in mid-summer. Fruit set was above 75% for most entries, including the heat-susceptible checks. Open-pollinated (OP) and hybrid cultivars exhibited a range of yields from 21.3 to 148.6 Mg/ha and fruit quality ratings from poor to excellent. The OP check ‘Super Sioux’ displayed consistently good yield and quality across years. The correlation between fruit set and yield was low (R 2 = 0.29) and significant only at the 0.10 level (P<0.09). The incidence of curly top (incited by BCTV infection) was less than 10% in both years, indicating mid-summer planting aided disease avoidance. ‘Flamenco’, the earliest variety, and two later maturing varieties ‘Florida 91’ and ‘Skyway 687’, are recommended for further evaluation. Mid-summer planting of small and medium-fruited tomato cultivars appears to be a viable option for organic fresh-market tomato production for the fall market in the Southwest USA.