Field evaluation of two fungicide rotation programs for control of Phytophthora blight in bell pepper, 2018-2019

摘要

The field trial was conducted on a research farm at the University of Florida's Tropical Research and Education Center in Homestead, Florida from Dec 2018 to Mar 2019. Plots were set up on raised beds that were 3-ft wide and covered with black plasticmulch. Each plot consisted of a 35-ft section with a 3-ft buffer zone between adjacent plots. Within each plot, there were 17 transplanted plants with a 2-ft spacing between two plants. In the trial, there were three treatments, with four replicates foreach treatment. All treatments were arranged in a randomized complete block design. Irrigation and fertigation were provided as per optimal requirements for bell pepper production in Florida by two drip irrigation tapes passing by both sides of each plant. Pepper plants were maintained following a pesticide program to control insect pests and foliar diseases other than phytophthora blight. Bell pepper var. 'Rampart' was seeded in the greenhouse on 9 Nov, 2018. Seedlings were transplanted into the fieldon 12 Dec, 2018, and drenched with Danitol at 3 ml/gallon to prevent the plants from the damage caused by cutworms. First treatment of soil drench was conducted on 12 Dec, 2018 by applying the chemical solutions at 35 ml per plant to the base of each plant. Subsequent treatments were conducted weekly by applying the chemical solutions at 0.18 gallon per plot through the irrigation drip line. Each of the plants was inoculated by placing 2 g of wheat seeds that had been infested by Phytophthora capsici for one month at the base and covering the inocula with soil. The first inoculation was made on 10 Jan, 2019, and two more applications made at a bi-weekly interval. To promote disease development, sprinkler irrigation was applied 2 hrs a day for every other day in dry weather. Disease was monitored twice a week after the first appearance of plant wilting. Final incidence of plant wilt was assessed on 13 Mar, 2019. Disease incidence was root square transformed prior to analysis. Student's t test was performed using the SAS statistical software Version 9.4 (SAS Institute Inc., Cary, NC) to separate the means of the disease incidence of the treatments at P = 0.05.