Evaluation of fungicides for management of downy mildew on baby leaf kale grown for spring mix, winter 2018

摘要

The objective of the experiment was to compare the efficacy of fungicides for management of downy mildew on baby leaf kale. The highly susceptible kale type 'lacinata', also known as dinosaur kale was planted in a commercial spring mix production field 10 miles southeast of Belle Glade, FL on 3 Feb 2018. The soil, classified as Pahokee muck with a soil pH of 7.0, was fertilized according to soil test recommendations. Kale was direct-seeded in twenty-two rows with a 2-in. row spacing on top of 8-in. raised beds formed on 6-ft centers. The crop was densely seeded for spring mix production, with an in-row spacing of approximately 1 inch. The experiment consisted of a randomized complete block design with 3 replications of ten treatments. Experimental units were 10-ft bed sections. Chemical treatments were applied using a CO2 backpack sprayer. The boom was equipped with a single Tee-Jet 11004 flat-fan nozzle, using two overlapping passes to cover each plot. Foliar sprays were applied at 30 psi, delivering a final spray volume of 63 gal/A. To avoid phytotoxicity issues due to any factor other than the fungicide themselves, no surfactants were used with any treatment. Downy mildew inoculum was known to be in the immediate area at planting, since plantings were staggered and earlier kale plantings had been observed supporting disease. Fungicide treatments were applied beginning at the true leaf stage and were applied on a 6-day schedule. The crop emerged on 7 Feb and applications were made on 17 and 23Feb. Disease incidence was assessed on 20, 23, and 26 Feb by visually assessing downy mildew severity within two 1 -ft2 randomly selected areas located in each plot.