34 BULLETIN 52, HAWAII EXPERIMENT STATION.- 
Table 16 shows the practical value of the iron-spraying treatment, 
even though it was not applied until after the plants had suffered 
during the greater part of their growing period from manganese- 
induced chlorosis. ^Plants starting to blossom" refers to the green, 
healthy plants on the sprayed rows whose flowering had been delayed 
by the effects of the manganiferous soil and in which the blossoms 
was just appearing. Only fruit that was completely destroyed is 
classed under " Plants with fruits cracked open and decayed." 
Fruit which showed only a few spots of decay was credited with full 
weight, although only a part of it could be used. No decay was seen 
on the rows of fruit which received the full number of sprayings. 
Although the increase in the average weight of the fruit was not 
as large as would be estimated from its appearance in the field, the 
increase in diameter and size of the fruit on sprayed rows, as men- 
tioned above, caused nearly all of them to class as No. 1, the value 
of which is considered nearly twice that of the No. 2. 
PRACTICAL ADVICE REGARDING THE TREATMENT. 
Although beneficial results from an iron-spray treatment, as 
described above, were obtained with pineapple plants which had 
suffered during the greater part of their growth from lack of iron, 
such late spraying is not advised. 
Sprayings at intervals of one to four months, depending upon the 
condition of the plants, are recommended for young crops. The 
color and general appearance of the plants should be used as an 
indication of their need of spraying. The plants should be sprayed 
whenever there is any indication of yellowing or of fading vigor, it 
being the idea to give them sufficient iron to keep them green and 
healthy. The exact number and times of sprayings can not be 
specified exactly for varying local conditions, but the most beneficial 
treatment for particular fields can easily be ascertained if the color 
and general vigor of the plant are used as indicators. 
The most economical and effective method of supplying the iron 
sulphate (copperas) appears to be that of spraying the plants with a 
fairly strong solution in the form of a fine mist. An approximate 
6 per cent solution (25 pounds of copperas to 50 gallons of water) has 
been found very effective in restoring the green color without seriously 
burning the plants. No injurious effects were noticed even when 
an application of about 14 gallons of an 8 per cent solution per acre 
was used in the fine spray on young plants. This solution may have 
to be weakened when a heavier spray is applied to young plants. 
Any form of sprayer or even a hand sprinkler may be used provided 
it applies about 10 pounds per acre of the copperas in solution. 
From 3 to 4 per cent (12 to 16 pounds per 50 gallons) of ammonium 
sulphate in the iron sulphate seems to give good results. It should 
be remembered that only one of the elements necessary for growth 
is supplied when the plant is sprayed with iron. Soluble phosphates 
and nitrogen as sulphate of ammonia or in organic form are recom- 
mended for use when commercial fertilizers are to be applied to the 
soils. Potash is not as necessary in fertilizer formulas for these as 
for other soils because manganese soils are fairly rich in potash as 
well as in phosphoric acid and nitrogen and should, therefore, prove 
fertile when iron is applied to the plants. Cannery ash, which is 
