THE NATIONAL NURSERYMAN 
227 
FERTILIZERS FOR MATURE TREES 
C. D. Jarvis, Connecticut 
Briefly stated, the manurial recommendations for an 
apple orchard are dependent upon the age of the trees; 
the vigor, as indicated by the annual growth; the nature of 
the varieties; the character of the soil; the previous 
treatment of the soil; the cultural system employed; the 
kind of cover crop; the kind of filler used; the nature and 
amount of other crops grown in the orchard; the avail¬ 
ability of fertilizing materials; the severity of pruning; 
the size of the expected crop; and to some extent, the 
character of the season. The formula mentioned below 
should be taken as a suggestion, ohly, and should be 
modified to suit special conditions. 
For mature apple trees on soil that is apparently in need 
of a complete fertilizer the following formula is suggested; 
Nitrate of soda (15% nitrogen or its equivalent) 200 lbs 
Muriate or sulphate of potash (50% potash or its 
equivalent).250 lbs. 
Raw ground-bone (20% phosphoric acid and 3% 
nitrogen or its equivalent).400 lbs. 
These amounts are intended for the annual treatment of 
one acre of orchard land. The amounts required for a 
single tree may be determined by dividing by thirty. This 
formula may be regarded as a moderate annual application. 
The amounts may be decreased for moderately small trees 
• and increased for larger ones. When leguminous cover 
crops are annually grown and turned under and when the 
trees are making sufficient growth, the amount of nitrate 
of soda may be greatly reduced or omitted entirely. The 
same change should be made, also, when trees have been 
severely pruned, as is usually done in the renovation of 
neglected orchards. For the immediate benefit of the trees 
it may be advisable the first year to supplement the above 
formula with 150 pounds of acid phosphate. This is for the 
reason that the phosphoric acid in the raw bone is mostly in 
an insoluble form and the trees would be unable to use 
much of it until the second season. Once in three or four 
years it may be advisable to apply, in addition to the above, 
about one ton of lime to the acre. Good results have 
followed the use of basic slag in apple orchards, and if 
five or six hundred pounds of this material is used every 
second season, in place of the raw ground-bone, the applica¬ 
tion of lime may be omitted. 
In seasons when the trees are bearing a heavy crop* of 
fruit, it may be advisable to supplement the above formula 
with a light dressing of soluble fertilizer about the latter 
part of June. This will tend to relieve the strain upon the 
trees and give them an opportunity to form fruit buds for 
the following season. About 50 pounds of nitrate of soda 
and 100 pounds each of muriate of potash and acid phos¬ 
phate should be the maximum amount to be applied at 
this time. There is great danger in applying fertilizer at 
this time, for if there should be a prolonged dry season it 
would not be dissolved until too late for the present season’s 
crop and would be likely to cause a second growth late in the 
season. For this reason the summer application should 
f ^ be made just before, or during, a rain. 
I ^ A knowledge of the functions of the various fertilizers 
I ik assist greatly in understanding the needs of the apple 
tree. Nitrogen favors the vegetable growth of leaf, wood, 
and fruit. Phosphoric acid is necessary in the formation 
of leaf and fruit buds and of seeds. Potash affects the 
color, quality, and flavor of the fruit and at the same time 
assists in the vital processes of growth. With these points 
in mind, the fruit-grower should keep a close watch of his 
trees with a view of supplying their individual needs. 
ARE ORCHARD HEATERS WORTH WHILE? 
The editor of The Fruit Grower, St. Joseph, Missouri, in 
the May issue of that paper presents an extremely interest¬ 
ing account of the fight against a 16 degree freeze in the 
Grand Valley of Colorado early in April. As peaches and 
apricots were in bloom, the various orchard heating devices 
were given a test which ought to be sufficient to show the 
skeptical what orchard heaters can do. Even the most 
optimistic can hardly expect that the entire crop in any 
of the orchards could have been saved, especially where a 
high wind was blowing, since 28 degrees is conceded to be 
the lowest point at which the trees are safe when in bloom. 
Fortunately, nearly all of the growers in this thickly 
planted valley had equipped themselves with orchard 
heaters, profiting by the experiences of recent years. 
When the temperature fell to the freezing point, a prelim¬ 
inary warning was sent out by the United States Weather 
Bureau, a system of signals having, been arranged, so that 
those growers having no telephone might not be at a dis¬ 
advantage. After the first alarm, growers kept watch of 
their thermometers distributed throughout the orchards, 
and before the temperature reached 28 degrees at least 
part of the fires were lighted. Nothing less than a small 
army of people is required to replenish the supply of fuel 
where coal heaters are used, and to inspect for proper action 
in the case of the oil heaters; and so great was the interest 
in the protection of the immense fruit crop that clerks in 
stores were permitted to leave their work in order to rest 
during the day and fight the cold at night; automobile 
owners furnished their machines to assist in carrying re¬ 
enforcements to camp, and Secretary Mahoney of the Grand 
Junction Chamber of Commerce was permitted to issue 
passes to those who would go from Grand Junction by 
train as volunteers. 
The writer states that by midnight on the night of the 
big freeze about three-quarters of a million heaters were 
blazing out in the darkness, but even then great damage 
resulted. What is expected ordinarily when orchard heat¬ 
ers are used is to supply sufficient fuel to keep them going 
eight or nine hours, as sunrise generally causes an immediate 
rising of the temperature. But this time it was not so. 
In the Cross orchard, whose 42 acres were equipped 100 
heaters to the acre, the workers were victorious over Jack 
Frost all night; but when with sun-up there came a drop of 
eight degrees in half an hour, Mr. Cross was so sure his crop 
had been completely destroyed that he sold his remaining 
oil to his neighbors. In other orchards, the men, confident 
of the beneficial effect of the sun’s rays, left their heaters to 
go to breakfast, only to have their crops practically wiped 
out before they returned. It was twelve hours from the 
time the first heaters were lighted until the danger point 
was passed. 
