Title: Control of pecan scab during the wet summer of 1965, in north Florda
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00076510/00001
 Material Information
Title: Control of pecan scab during the wet summer of 1965, in north Florda
Physical Description: Book
Creator: Large, John R.
Publisher: Big Bend Horticultural Laboratory, University of Florida
 Record Information
Bibliographic ID: UF00076510
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 145505427

Full Text




BIG BEND HORTICULTURAL LABORATORY : --.. .-
/ --2 Monticello, Florida / Y "'
', J./ ,.


March 23, 1966

Big Bend Hort. Lab. Mimeo Report BBL66-3 /


CONTROL OF PECAN SCAB DURING THE WET SUMMER
OF 1965, IN NORTH FLORIDA

by JOHN R. LARGE1


An evaluation of fungicide formulations and experimental fungicides
for control of pecan scab was made in Jefferson County in the Big Bend Hort-
icultural Laboratory orchard of Mahan, Schley and Moore varieties. In 1965
environmental conditions were highly favorable for disease development, the
rainfall from January 1 to September 9 was 54405 inches, which was 10.57
inches above normal (43.48 ins.).

The orchard was sprayed 6 times, April 14, May 14, June 25, July 9
and 26 and August 8th with a 35 gpm hydraulic sprayer at 450 psi. Insect-
icide was used in the June, July 9th and August applications.

Data were taken August 18 on green nuts of the three varieties. A
scab index figure (range 0-4), as used by Diener and Garrett (1), was cal-
culated from 50 nuts per tree from each of seven trees of Mahan, four trees
of Schley and three Moore trees. Data were recorded as: Clean no scab
on the shuck; Class 1 trace to 10%; Class 2 11 to 25%, Class 3 -
26 to 50% and Class 4 4 51 100%. The number of nuts in each class
was multiplied by the class number. The resultant figures were summed and
divided by the number of nuts to give the scab index for each tree. The
mean, of 7 replications for Mahan, 4 replications for Schley and 3 repli-
cations for Moore, was calculated for each treatment (Table 1). These
data are also presented as the percentage of nuts with heavy, light or no
(clean) visible scab infection. The figures under light infection represent
means of the data from classes 1 and 2 and under heavy infection from classes
3 and 4. The nuts with heavy shuck infection are usually worthless and fre-
quently drop before harvest. Nuts with light infection are usually poorly
filled and of poorer quality than nuts free from scab.

Results of the 1965 experiments are shown in Table 1. Du-Ter as a wet-
table powder or as a liquid at high (1 1/2 lbs. or 19.6 oz.) or low rates of
application (1/2 lb. or 6.2 ozs.) was the most effective of the fungicides
tested for controlling scab. Dodine (Cyprex) at 1/2 lb./100 compared with
Zineb + Oil, 2 lbs. + 1 qt./100, but these two chemicals were not as effect-
ive as bordeaux mixture. Nuts sprayed with Captan 2 lb./100 or Captan,
4 applications followed by 2 applications of Dodine, 1 lb./100 were only
a little better than the nuts from unsprayed trees.


1Associate Plant Pathologist, Big Bend Horticultural Laboratory,
Monticello, Florida.
150 cc








-2-



Du-Ter at 1/2 lb./100 was more effective than Dodine at this concen-
tration. Further investigations of Du-Ter is warranted to determine the
minimum effective dosage and phytotoxicity on pecan varieties. Phyto-
toxicity again developed on Moore trees sprayed in April with Dodine
(Cyprex) 1/2 lb./l0. No phytotoxicity was noted on Moore trees sprayed
with Du-Ter.

Grateful acknowledgement is made to the American Cyanamid and Thompson-
Hayward Companies for experimental materials.


LITERATURE CITED

1. Diener, U. L. and Frank E. Garrett. 1965 Control of Pecan scab
in 1964 in Southwest Alabama. Proc. Southeastern Pecan Growers Assoc.
58: 73-74.








Table 1. Control of Pecan


-3-
Scab in North Florida in 1965.

MAHAN VARIETY


Fungicide Conc. of Rate/100 gal. Mean Scab Infection % Lbs.
Act. Chem. Scab Clean Light Heavy nuts har-
Index vested
per tree

Du-Ter 20 20% WP 1 1/2 lbs. 0.02 98.3 1.7 .0 46.7

Du-Ter 20% WP 1/2 lb. 0.06 95.5 4.1 0.4 24.9

Du-Ter Flow. 2#/gal. 19.2 ozs. 0.02 98.1 1.9 0 56.7

Du-Ter Flow. 2#/gal. 7.6 ozs. 0.07 92.8 6.3 0.9 37.6

Dodine (Cyprex) 65% WP 1/2 lb. 0.96 49.0 44.3 6.7 18.0

Bordeaux 4-1 then 6-2 0.55 62.7 36.4 0.9 24.4

Zineb + Oil 2 lbs. + 1 qt 1.10 48.5 41.6 9.9 38.9

Captan 50% WP 2 lbs.(4 appl.)
then Dodine 65% WP 1 lb.(2 appl.) 2.06 20.4 43.1 36.5 12.9

Captan 50% WP 2 lbs. 2.34 21.1 31.3 47.6 15.8

Not sprayed 3.46 0.2 9.6 90.2 1.8

MOORE VARIETY

Du-Ter 20% WP 1 1/2 lbs. 0.02 98.1 1.9 0 54.4

Du-Ter 20% WP 1/2 lb. 0.01 99.1 0.9 0 28.3

Du-Ter Flow. 2#/gal. 19.2 ozs. 0.01 99.4 0.6 0 6.2

Du-Ter Flow. 2#/gal. 7.6 ozs. 0.03 97.6 2.3 0.6 33.0

Dodine(Cyprex) 65% 1/2 lb. 0.63 56.6 42.2 1.2 2.7

Bordeaux 4-1 then 6-2 0.41 74.3 24.6 1.1 17.7

SCHLEY VARIETY

Du-Ter 20% WP 1 1/2 lbs. 0.07 94.8 3.3 1.9 13.8
Du-Ter 20% WP 1/2 lb. 0.06 94.3 5.1 0.6 7.1
Du-Ter Flow. 2#/gal. 19.2 ozs. 0.03 97.5 2.52.5 0 13.2
Du-Ter Flow. 2#/gal. 7.6 ozs. 0.02 97.6 2.4 0 10.3
Bordeaux 4-1 then 6-2 0.31 79.9 24.6 0.6 15.7
Not sprayed 3.25 0 11.3 88.7 0




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs