20 BULLETIN 829, IT. S. DEPARTMENT OF AGBJCITLTTTKE. 
just been removed grew without any evidence of the disease. The 
virus does not live over in the soil and it is doubtful whether it exists 
there at any time. In this respect the mosaic does not by any means 
present the practical difficulties in the way of control measures to be 
met with in root-rot. Root-rot, in fact, is to be regarded as a far 
more serious problem for the Louisiana cane planter than mosaic on 
this account. 
RELATION TO DISINFECTANTS. 
Treatment of infected seed pieces by soaking in strong Bordeaux 
mixture or corrosive sublimate previous to planting has had no effect 
on the course of the disease. All shoots were typically mottled as 
soon as they appeared. It was hardly to be expected that superficial 
disinfection could influence the virility of the infectious principle when 
all our evidence indicates that the latter permeates the internal 
tissues, or at least the vascular systems of affected plants. 
RELATION TO FERTILIZERS. 
Many experiments 1 have been performed in Porto Rico to deter- 
mine the effect of applying fertilizers, since the claim was made by 
many planters that mosaic was due to insufficiency of plant nutrients 
in the soil. Filter press cake, sulphate of ammonia, and lime in 
various combinations, together with turning under cover crops and 
good tilth, had no noticeable effect on the disease as compared with 
control plats. Standard complete fertilizers were also tried. Beyond 
a slight stimulation in growth and the darker green color of the treated 
plants, there was no observed effect. Diseased plants may be expected 
to respond to good growing conditions the same as healthy ones, 
but the same constant difference between healthy and diseased plants 
is maintained under all conditions. The diseased stalks remain below 
the average weight for healthy stalks and are just as capable of 
spreading the disease. Liming the soil has no more effect on diseased 
plants than the application of fertilizers. 
CONTROL. 
It is interesting to note that in Java long experience has demon- 
strated that the disease can best be held in check by careful selection 
of healthy plants for seed and by replanting fields with cuttings taken 
from the same field, in preference to buying cuttings of unknown 
origin or moving the cuttings from field to field on the same plan- 
tation. The use of such methods practically amounts to tacit 
admission of the infectious nature of cane mosaic, although it is 
ascribed to "bud variation." The facts which have most impressed 
the Dutch planters are that cuttings from diseased stalks always 
Stevenson, John A. The "mottling" disease of cane. Porto Rico Insular Exp. Sta. Ann. Rpt., 
1916-17, p. 40-77, 1917. [Literature] p. 76-77. 
