Evaluation of fungicides for field control of sweetpotato black rot caused by Ceratocystis fimbriata, 2017

摘要

This experiment was conducted at Central Crops Research Station in Clayton, NC. Covington sweetpotatoes were transplanted on 2 Jun and spaced at 1 plant per foot in row. The plots were 20 feet long, and the spacing between rows was 45 inches. The field was planted in sweetpotato the previous year. Treatments were randomized in a random complete block design with four replications per treatment. Sweetpotato slips were inoculated prior to transplant by soaking slips in a C. fimbriata spore suspension (1 x 106 spores/mL) for 20 minutes. Drench treatments were applied immediately following transplanting to the base of each plant. All treatments with a spray application were applied immediately after transplanting. Treatments with multiple spray applications (Quash, Luna Tranquility, Quadris Top, and Priaxor at 32, 16, and 8 floz/A) were applied on 3-week intervals on 23 Jun, 14 Jul, and 4 Aug. Spray treatments were applied with a CO2 powered backpack sprayer at 40 gal/A. Drench treatments were appliedby pouring 75 mL of fungicide mixture at the base of each plant. Sweetpotatoes were harvested on 13 Oct. Once harvested, roots were weighed, washed, sorted by size, counted, split into two groups for curing, and rated for black rot. After rating, only U.S. No. 1 (3-9 inches) sized roots were cured for either 2 or 4 days. After curing, roots were rated again for black rot. Data were analyzed in the software SAS (SAS Institute, Cary, NC) using Proc GLIMMIX with lsmeans (pdiff.) to differentiate differences between treatment means.