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Joumal of Agricultural Research 
Vol. XXVIII, No. 4 
of disposing of the disease is less popular than formerly, owing to the apparent 
adaptation of the fungus to the more resistant ones. Spraying is now being 
considered somewhat more seriously as a means of reducing the loss by scab, 
but as yet most of the growers seem to prefer top-working to the more pains¬ 
taking and labor-involving operation of spraying. 
During the past two years the writer, in search of the most satisfactory spray 
for pecan-scab control, has been devoting considerable attention to trials with 
different kinds of fungicides commonly used in apple and peach orchards. 
In the order named, Waite, 4 * Spooner, 6 McMurran and Demaree, 6 and Neal 7 
have shown Bordeaux mixture to be quite effective as a spray for the control of 
pecan scab. Because this spray sometimes causes serious injury to the foliage 
an attempt was made to find some spray that would be effective and yet cause 
no serious foliage injury. The following fungicides have been used: Sulphur 
dust, Bordeaux dust, lime sulphur solution, wettable sulphur, self-boiled lime 
sulphur, lime sulphur modified by the addition of 1 pound of copper sulphate 
to each 50 gallons of spray and self-boiled lime sulphur modified by the addition 
of 2 pounds of copper sulphate to each 50 gallons of spray. Both types of dust, 
wettable sulphur and self-boiled lime sulphur, even when modified with copper 
sulphate, proved to be ineffective under the conditions tried. Lime sulphur 
solution when used at the strength of 1 gallon of the concentrated material 
(32 to 33° B.) to 50 gallons of water, controlled the disease quite satisfactorily 
during the season of 1922. This spray, however, proved to be much less effective 
during the rainy summer of 1923. From the results of the work so far conducted, 
it appears that the choice of a spray will be limited to Bordeaux mixture which is 
ordinarily effective but may cause serious foliage injury under certain weather 
conditions, and lime sulphur solution, a spray only slightly injurious to the 
foliage, but whose capabilities as a preventive of pecan scab are not yet fully 
demonstrated. 
Since it is difficult to control pecan scab even under the most favorable condi¬ 
tions, advantage should be taken of every possible opportunity to reduce in 
number the sources of infection. As previously mentioned, the unfolding leaves 
are quite susceptible to spray injury. The foliage is also very susceptible to 
scab infection during this same period. Therefore, the importance of destroying 
in so far as possible all the sources of the primary infection is quite evident. 
The writer has been informed of instances where fire swept through badly infected 
orchards, burning the d6bris on the surface of the ground. As a result, it was 
reported that there was a very pronounced reduction in the amount of the 
disease in these orchards during the season following. The effect of numerous 
overwintering infection sources on control by spraying was brought to the 
writer’s attention in a very striking manner last season. An orchard of the 
variety Schley, at Quincy, Fla., was sprayed on the following dates: April 10, 
May 9, May 23, June 13, July 5, and 27, 1923. On account of frequent rains 
during June and July, the spray could not be applied according to any prear¬ 
ranged schedule. No attempt was made to destroy the sources of the primary 
infections. The soil had not been plowed and the last year’s leaves, shucks and 
mummied nuts were left upon the ground. Consequently, a severe primary 
infection of the leaves took place very early in the spring, even before it was 
4 Waite, M. B. nut diseases with special reference to the pecan. Proc. Amer. Pomol. Soc. 32; 
182-190. 1911. 
• Spooner, C. S. pecan scab (fusicladium effusum). Georgia State Bd. Ent. Bui. 49: 38-43, illus. 
1918. 
* McMurran, S. M., and Demaree, J. B. diseases of southern pecans. U. S. Dept. Agr. Farmers 
Bui. 1129, 22 p., illus. 1920. 
7 Neal, D. C. spraying experiments for the control of pecan scab in Mississippi. Miss. Agr 
Exp. Sta. Bui. 203, 14 p., illus. 1921. 
