19, 2 
Lee: Citrus-canker Control 
147 
Work on this plat was begun by spraying with lime sulphur, 
but it became apparent, as at Los Banos, that the lime-sulphur 
solution was easily washed from the leaves by the beating, 
driving rains. Thereafter a change was made to Bordeaux 
mixture, except in seasons when the rainfall was less intense. 
In such seasons of less rainfall, because of the increase of scale 
insects following the successive use of copper sprays, lime sul- 
phur was used whenever possible for its action as a scalecide 
as well as for its action against canker. 
PLAT II, ORCHARD A, LAMAO 
This plat consisted of three rows of trees adjacent to the rows 
of Plat I ; the character of the trees and degree of canker infec- 
tion throughout the season are shown in Table 10. All trees in 
this plat were left entirely untreated. Unfortunately these trees 
are for the most part varieties different from those that appear 
in the sprayed plats; nevertheless, they may afford some basis 
for comparison between the treated and the untreated plats. 
Although some of the trees in this untreated plat show re- 
ductions in the amount of canker infection, some show increases. 
As a whole, then, this plat, serving as a control, can be used 
as a basis for comparison with the treated plats. The trees 
being untreated also afford something of an idea of the sus- 
ceptibility of the species represented in this plat. 
PLAT III, ORCHARD A, LAMAO 
This plat consisted of three rows of trees, the character of 
which is shown in the tabulation of the degree of canker in- 
fection during the various stages of control experiments. The 
treatment of the plat was as follows: 
September 1, 1917. Lime sulphur 1-40 solution. 
September 20, 1917. 4-4-50 Bordeaux mixture. Trees pruned for 
twig cankers. 
October 23, 1917. 4-4-50 Bordeaux mixture. 
November 20, 1917. Formalin 1-80 solution as a clean-up spray. 
November 28, 1917. Formalin 1-100 solution plus powdered, neutral, 
lead arsenate to make 1-50 mixture. 
December 6, 1917. Lime sulphur 1-40 solution plus formalin 1-80. 
January 9, 1918. Neutral Bordeaux mixture plus formalin 1-100 and 
Yothers’s oil emulsion. Trees pruned for twig cankers. 
May 31, 1918. Lime sulphur 1-30 solution. 
June 24, 1918. Lime sulphur 1-35 solution plus formalin 1-100. 
August 1, 1918. Lime sulphur 1-35 solution plus resin, sal-soda sticker. 
The complete reversal from Bordeaux mixture to lime-sulphur 
solution in 1918 was necessitated by severe attacks of scale in- 
sects following the Bordeaux applications. 
