Everglades Station Mimeo Report EES 68-7 March 1968


 Rate and Interval of Fungicide Application on
 the Control of Celery Early Blight

 R. D. Bergerl/


 Purpose: Some celery growers have experienced poor early blight control
 on celery by following an apparently sound spray program using a good fungicide
 with applications every four to seven days., More frequent applications should
 undoubtedly provide better disease control because of the greater opportunity
 to furnish the youngest plant growth with an early fungicide coverage and also
. to keep the entire foliage canopy covered with a coating of fresh fungicide.
However, in order to make more frequent applications economically feasible, a
reduction in spray concentration would be necessary. The experiment reported
here was designed to test this hypothesis and to determine the comparative
efficiency of two fungicides, Daconil 2787 (Diamond Alkali Company) and Dithane
M-45 (Rohm and Haas Company). Previous year's data indicated Daconil gave good
commercial control at 0.75 Ibs/A applied twice-a-week and the experiment was
also designed to find the minimum concentration of this material which would
provide effective disease control.

 General: Celery transplants of variety Utah 52-70H were set on October 31,
 1967. Weed control was obtained by one application of Randox-Vegadex. Insect
 control was maintained by periodic applications of Cygon, Dibrome, and Diazinon.
 Fungicide application was accomplished by the pathology plot sprayer operating
 at approximately 150 psi and about 150 gallons per acre. The experiment was
 terminated on January 29, 1968.

 Disease situation: Early blight incited by Cercospora apii did not occur
 for any significant amount until mid-December even on the unsprayed rows.
 Infrequent favorable infection periods during the latter part of the trial
 provided only a slow, moderate build-up of disease but the disease was uniformly
 severe on the guard and check rows when the trial was terminated.

 Results: Disease severity data and treatment comparisons are given in the
 accompanying tables.

 Discussion and summary: The results presented here indicated that reduction
 in spray concentration can provide effective disease control if the number of
 applications are increased. The minimum amount of material necessary that gave
 effective control was .75 Ibs/A/three times a week for Dithane M-45 (total 2.25


 1/ Assistant Plant Pathologist, Everglades Experiment Station, Belle Glade,
 Florida