MANGANESE CHLOROSIS OF PINEAPPLE. 31 
sufficient for spraying. Pipes lead from the rear to the front tank 
and from the front tank to the spray nozzles, which are placed on the 
long arm extending crosswise from the sprayer. A gauge on the front 
tank sh ws the pressure, which is kept at about 30 to 40 pounds when 
spraying. (PI. II, figs. 1 and 2.) As the machine moves forward it 
sprays lour rows at a time. Many complicated sprayers have been 
tried by the various plantation managers, but the single-wheel type 
of sprayer, similar to that described above, is satisfactorily used by 
most of them. The principal modification has been in the use of an 
air compressor which is driven from the large supporting wheel to 
furnish the pressure and to take the place of the more expensive 
carbon-dioxid tank, or the use of a pump similarly driven which 
delivers the solution from the tanks to the spraying nozzles under 
pressure. 
SPRAYING COSTS. 
The cost of spraying is considered negligible in comparison with the 
expenditures necessary in the raising of pineapples. With the 
experimental sprayer described above the cost amounted to approxi- 
mately 60 cents per acre for each spraying. The yearly cost per acre 
for spraying is not large, since the fields are sprayed on the average 
only about once a month. 
SMALL FIELD TESTS. 
All of the fields of the cooperating plantation where u manganese 
yellow" was evident were sprayed with excellent results. The man- 
ganiferous soil had been particularly injurious in one large field of 
young plants. A sample of the soil from this field, given in Table 
2 as No. 636, showed 4.8 per cent of manganese as Mn 3 4 . The 
plants throughout the field were very yellow and showed no trace of 
green, while many of the plants which were about six months old had 
turned brown from the tips of the leaves . and were dying. The 
spra}'ing treatment was applied with immediate benefit, and in six 
months' time the whole field presented a very vigorous green and 
healthy appearance. 
A 130-acre field was given three sprayings about the time of 
flowering or later in May and June. This field was not wholly 
uniform, the plants in some sections appearing slightly affected and 
in others showing very decided effects from the manganiferous soils. 
Immediate results were evident when the spraying treatment was 
applied to the whole field, the plants becoming green and vigorous 
and the stunted fruit rapidly developing green color and making 
vigorous growth. The results of analysis of a sample of this soil, 
taken under the green sprayed plants, show 5.58 per cent of man- 
ganese present as Mn 3 4 . (See Table 2, No. 640.) An adjoining 
unsprayed check row was very yellow and bore small red fruit. The 
plantation records of this field show an average yield of about 13 tons 
of fruit per acre. 
MAIN FIELD TEST. 
The field in which this test was made lies in the Halemanu district 
of Oahu, where the most highly manganiferous soils occur. The 
Elantings were made on virgin soil to which commercial fertilizer had 
een applied at the rate of 600 pounds per acre. As the formula for 
this fertilizer is the property of the cooperating plantation, it can not 
