Evaluation of fungicides for managing Phytophthora fruit rot in watermelon, Brooks County, Georgia, 2018

摘要

Fungicides were evaluated for their efficacy to manage Phytophthora fruit rot, caused by Phytophthora capsici. The experiment was conducted in a grower's field in Brooks County, GA that had a history of epidemics of Phytophthora fruit rot. Watermelon'Troubadour' were transplanted onto single row beds covered with 18-in. black plastic mulch on 22 Mar. Beds were on 6-ft centers with 3-ft plant spacing within rows. Plots were 20-ft long with and used 5-ft planted borders between plot ends. The trial was arranged in a randomized complete block design with four replications with 10 plants per replication. Plots were drip irrigated weekly and as necessary using a drip tape irrigation system. Fertility and insecticide treatments were applied according tothe University of Georgia Extension recommendations. Natural infection was relied upon for initial inoculum. Fungicide treatments were applied using a John Deere 6155 sprayer calibrated to deliver 40 GPA at 125 psi through TX-10 hollow cone nozzles. Themean rainfall received during March and June was 2.5 in. and 4.2 in., respectively. The average high and low temperatures for the month of March were 85° and 63° F, respectively, and for the month of June were 92° and 71° F, respectively. On 20 Jun,fruit from each plot were harvested and incubated under standard room temperature (78° F) for 48-h. Ratings for disease incidence were assessed on 22 Jun as percentage of fruits with visible symptoms typical of P. capsici. Data were analyzed using the software ARM (Gylling Data Management, Brookings, SD), analysis of variance (ANOVA) and the Waller-Duncan test to separate means.