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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Plant Pathology Research » Research » Publications at this Location » Publication #396315
Research Project: Mitigation of Domestic, Exotic, and Emerging Diseases of Subtropical and Temperate Horticultural Crops

Location: Subtropical Plant Pathology Research

Title: Using environmental data to determine timing of chemical applications in north Florida watermelon production

Author
item DA SILVA, SUSANNAH - University Of Florida
item PARET, MATHEWS - University Of Florida
item HOCHMUTH, BOB - University Of Florida
item IRIARTE, FANNY - University Of Florida
item BROUGHTON, BENJAMIN - University Of Florida
item ROBERTS, PAMELA - University Of Florida
item Turechek, William

Submitted to: Cucurbitaceae Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/18/2022
Publication Date: 10/30/2022
Citation: Da Silva, S., Paret, M., Hochmuth, B., Iriarte, F., Broughton, B., Roberts, P., Turechek, W. 2022. Using environmental data to determine timing of chemical applications in north Florida watermelon production. Cucurbitaceae 2022.

Interpretive Summary: Three important foliar diseases affecting watermelon production in North Florida are powdery mildew, gummy stem blight, and downy mildew. Field trials were conducted at the North Florida Research and Education Center in Live Oak, FL in 2020, 2021, and 2022 to evaluate the use of the MELCAST advisory program for timing fungicide applications for control of these diseases. Analyses indicated that weekly applications of fungicides and MELCAST-driven programs provided statistically better disease control when compared to a water control (P<0.05). This study showed the potential of using MELCAST for reduced use of fungicides for effective watermelon disease management in North Florida.

Technical Abstract: Three important foliar diseases that affect watermelon production in North Florida are powdery mildew, gummy stem blight, and downy mildew. In the spring of 2020, a field trial was conducted at the North Florida Research and Education Center in Live Oak, FL to evaluate the use of the MELCAST advisory program for timing fungicide applications for control of powdery mildew. The trial was repeated in the spring of 2021 and 2022, but expanded to include management of downy mildew and gummy stem blight. The spring 2020 trial consisted of six treatments (i.e., spray programs): a standard program that targeted powdery mildew, a standard program that included secondary fungicides targeting downy mildew and gummy stem blight, and three MELCAST-driven programs with fungicides being applied when the sum of the Environmental Favorability Index values exceeded 30, 35, and 40 or at 14 days – whichever came first – and a water sprayed control. The 2021 and 2022 trials consisted of eight treatments: a standard program that targeted powdery mildew, a program that targeted downy mildew, a program that targeted gummy stem blight, a program that targeted the diseases observed in the field, and three MELCAST-driven programs as described above that also target the observed diseases. Disease evaluations were made using the Horsfall-Barratt scale, and disease progress was calculated using the area under the disease progress curve (AUDPC). Statistical analyses of the 2020 AUDPC data indicated weekly application of the standard with the secondary fungicide provided statistically better control of downy mildew than all other treatments (P<0.05). Statistical analyses of 2021 and 2022 data indicated the weekly standard programs and MELCAST-driven programs provided statistically better disease control when compared to the water control (P<0.05). This study shows the potential of using MELCAST for reduced use of fungicides for effective watermelon disease management in North Florida.