|MAY III, W|
|Wechter, William - Pat|
Submitted to: Plant Disease Management Reports
Publication Type: Research Notes
Publication Acceptance Date: 1/10/2007
Publication Date: 3/1/2007
Citation: Keinath, A.P., Dubose, V.B., May Iii, W.H., Wechter, W.P. 2007. Evaluation of Actigard and Kocide to Manage Bacterial Leaf Spots on Turnip Greens, 2006. Plant Disease Management Reports. (online). Report 1:V103. DOI: 10.1094/PDMR01. The American Phytopathological Society, St Paul, MN.
Technical Abstract: The trial was conducted on a commercial farm near Pelion, SC, where bacterial leaf spot diseases had been observed previously on leafy brassica greens. The soil was Lakeland sand. Fertilizing, watering with overhead center-pivot irrigation, and insect control were done by the cooperating grower. The experimental design was a separate Latin square for each cultivar with six replications. Leaf spot severity was rated with a 0-to-15 point Horsfall-Barratt. The nonsprayed, Actigard full rate, and Kocide alone treatments were harvested by arbitrarily selecting a 20-in.-long section in each of two rows of each plot and cutting all foliage in the two sections. Fresh weight was determined and then 100 leaves were selected arbitrarily and sorted into healthy and diseased classes. Area under the disease progress curve (AUDPC) and yield data were analyzed with SAS, PROC MIXED, version 8e. A leaf-spotting pathovar of X. campestris was isolated from all leaves collected from nonsprayed plots at the first three ratings and at harvest. (Pathovar identification of this xanthomonad is in progress.) P. syringae pv. maculicola was isolated from a few leaves collected from nonsprayed plots at the first rating only. On ‘Topper’ all treatments reduced AUDPC compared with the nonsprayed control. Kocide plus either the full or half rate of Actigard was more effective than Kocide alone in reducing AUDPC. On ‘Alamo,’ which was slightly less susceptible than ‘Topper,’ all treatments except Kocide reduced AUDPC compared with the nonsprayed control. Actigard alone was more effective than either Kocide alone or Kocide plus two applications of Actigard. With both cultivars, there was no difference between the full and half rates of Actigard when it was combined with Kocide. There also was no difference between two and four applications of Actigard combined with Kocide. There were no significant differences among treatments for fresh weight or percentage of healthy leaves. Because of the low percentage of healthy leaves, the level of control provided by the best treatments was not commercially acceptable.