THE PRINCIPLES AND PRACTICE OF SPRAYING
The spraying of fruit trees in the United States is of comparatively
recent origin, having been a general commercial practice for less than
two decades. It involves the principle of applying with force and in
the form of a fine rain or mist, water in which a poison or a
substance which kills by contact is suspended. The first application
of the principle was against chewing insects with hellebore. Pure
arsenic was early used and soon led to the use of other arsenicals.
Our greatest fungicide, Bordeaux mixture, was discovered by accident
in 1882 when it was found to control mildew in France. Up until about
five years ago Bordeaux mixture as the fungicide and paris green as
the poison were almost universally used. Within the last few years,
however, there have been developed two substitutes which, although
known and used to some extent for twenty years, have only recently
come into such general use as practically to replace the old sprays.
These are lime and sulphur as the fungicide and partial insecticide
and arsenate of lead as a partial insecticide.
The necessity for and the advisability of spraying have already been
pointed out. There is an increasing demand for fine fruit the
supplying of which is possible only with thorough spraying. In the
humid East especially the competition of more progressive sections in
the West is demanding more and better spraying. There is no cure-all
in this process. It does not make a tree more fruitful except as it
improves its general health, but it does bring a larger percentage of
the fruit to perfection. Certain knowledge is fundamental; the grower
must know what he is spraying for, when and with what to combat it and
how to accomplish the desired result most effectively.
Spraying is an insurance against anticipated troubles with the fruit,
and the best and most successful growers are those most completely
insured. It has many general advantages also. It stimulates the grower
to a greater interest in his business because of the extra knowledge
and skill required. It compels thoroughness. It necessitates spending
money, therefore a return is looked for. To be sure, it is only one
of the operations necessary to success, but it enables us to grow a
quality of fruit which we could not obtain without it.
SPRAY MATERIALS are conveniently divided into two classes,
insecticides and fungicides. An insecticide is a poison by which the
insect is killed either directly by eating it, or indirectly by the
caustic, smothering, or stifling effects resulting from closing its
breathing pores. Direct poisons are used for insects which eat some
part of the tree or fruit and are called stomach poisons. Sprays which
kill indirectly are used for insects which suck the sap or juice from
the tree or fruit and are called contact sprays. Arsenical compounds
have supplanted practically all other substances used to combat
external biting insects. Two stomach poisons are commonly used,
namely, arsenate of lead and paris green, but the former is rapidly
replacing the latter.
ARSENATE OF LEAD is prepared by mixing three parts of crystallized
arsenate of soda with seven parts of crystallized white sugar
(acetate) of lead in water, but it will not as a rule pay the grower
to mix his own material, as arsenate of lead can be purchased in
convenient commercial form at a reasonable price. The preparation on
the market is a finely pulverized precipitate in two forms, one a
powder and the other a paste. These are probably about equally good
and are readily kept suspended in water. Less free arsenic is
contained in this form than in any other compound of arsenic, making
it safer to use, especially in heavy applications. Arsenate of lead
may be used without danger of burning the foliage as strong as five or
six pounds to fifty gallons of water, but three pounds is the usual
and a sufficient amount for the control of any apple insect for which
it is efficacious.
PARIS GREEN is being rapidly displaced by arsenate of lead for several
reasons. It is a compound of white arsenic, copper oxide, and acetic
acid. The commercial form is a crystal which in suspension settles
rapidly, a serious fault. It is more soluble than arsenate of lead and
hence there is greater danger of burning the foliage with it.
Moreover, it costs from twenty to twenty-five cents a pound, and the
arsenate of lead can be purchased for from eight to ten cents a pound.
The amount which it is safe to use in fifty gallons of water is from
one-half to three-quarters of a pound. When paris green is used alone
as a poison lime should be added. Both these arsenicals should be
thoroughly wet up by stirring in a smaller receptacle before they are
put into the spray tank, in order to get them in as complete
suspension as possible. They may be used in the same mixture with
Bordeaux or lime sulphur.
CONTACT SPRAYS.--Four compounds are used as contact sprays in
combating sucking insects, namely, lime sulphur, soaps such as whale
oil soap, kerosene emulsion, and tobacco extract. Of these lime
sulphur is the most used and for winter spraying is probably the best.
This preparation is made by boiling together for one hour or until
they unite, twenty pounds of quick lime, fifteen pounds of flower of
sulphur, and fifty gallons of water. Although the home made mixture is
much cheaper than the commercial form which may be purchased on the
market, many people prefer the latter because of the inconvenience and
trouble of preparing the mixture, although there is nothing difficult
about it.
This contact spray is used chiefly for the San Jose scale and the
blister mite, and in order to control these must be applied strong on
the dormant wood. The strength necessary will vary from one part of
the mixture above mentioned or of the commercial preparation, to from
seven to ten parts of water, according to the density test of the
material, which should be around twenty-eight per cent. Beaume (a
scale for measuring the density of a liquid) for home made, and
thirty-two per cent. for the commercial mixture.
Any good soap is effective in destroying soft bodied insects such as
plant lice. The fish oil soaps, although variable in composition, are
often valuable, especially the one known in the trade as whale oil
soap. This soap dissolved in water by boiling at the rate of two
pounds of soap to one gallon of water, makes a good winter spray for
scale but should be applied before it gets cold as it is then apt to
become gelatinous. For a summer contact spray against lice, one pound
of soap to seven gallons of water is strong enough to be effective. It
is objectionable because of its odor and because it is disagreeable to
make and handle. Lime sulphur is to be preferred as a winter spray,
but the soap spray is often necessary and valuable for summer sucking
insects.
Kerosene emulsion was formerly more commonly used than now against the
scale and plant lice. It is a mixture of one-half pound of soap and
two gallons of kerosene in one gallon of water--preferably in hot
water. For dormant trees one gallon of this mixture should be diluted
with six gallons of water. While this spray is effective it is no more
so than lime-sulphur and is quite difficult and disagreeable to
handle. As a summer spray, however, it is often necessary. Several
preparations of petroleum known as the miscible oils are sometimes
used. Their use is the same as that of lime-sulphur and they are not
as good.
Within the last few years a tobacco concoction known as black leaf
tobacco extract (nicotine sulphate) has come into quite common use. It
can be purchased commercially under various brand names, and should be
diluted according to its strength, but usually about one part to fifty
of water. It may be made by boiling one pound of good tobacco stems in
two gallons of water for one-half-hour. Objections to it are that it
evaporates very quickly, although it is supposed to be non-volatile,
and that it is expensive, but it is very convenient to use, can be
readily mixed with other summer sprays, and is very effective against
plant lice and mites.
BORDEAUX MIXTURE. Fungicides are mixtures of chemical compounds made
up for the purpose of controlling plant diseases caused by a class of
plant weeds known as fungi. There are three commonly well known and
used fungicides, Bordeaux mixture, commercial lime sulphur, and the
self-boiled lime-sulphur. The Bordeaux mixture is the best all-around
fungicide known. It is a mixture of three pounds of copper sulphate
(blue vitriol or bluestone) with three or more pounds of fresh burned
stone lime in fifty gallons of water. The two compounds should be put
together as fruit growers say "with water between," that is each
should be diluted with the water separately before the two are mixed.
The best plan is to have stock mixtures of each in barrels, fifty
gallon cider or vinegar barrels making good receptacles for the
purpose. Place the bluestone in an old fertilizer or meal sack and
suspend it about midway in the barrel of water. In a few hours it will
all be dissolved and will remain in suspension for some length of time
very well. If say fifty pounds of the copper sulphate are dissolved in
fifty gallons of water, each gallon of water will contain one pound of
the bluestone, which makes a very convenient way to measure it. So
also fifty pounds of fresh burned stone lime should be placed in a
barrel--in this case in the bottom of the barrel rather than in a
sack--just covered with water and allowed to slake, more water being
added as required up to fifty gallons. If too much water is added to
the lime at the first it will be "drowned" and its slaking checked.
These two stock mixtures, each gallon containing one pound of the
copper sulphate or one pound of the lime, are then mixed together.
It is well to fill the tank about half full of water, then put in the
required amount of the copper sulphate, and after stirring well add
the lime milk. It is a good plan to add an excess of lime as it
minimizes the danger of burning and aids the mixture in sticking to
the leaves well. If one is sure that he has at least as much lime, or
an excess of lime, it will not be necessary to test the mixture, but
if he is not, a simple test may be made with ferro-cyanide of
potassium, obtained at a drug store. A few drops of this mixture will
disappear if the lime is equal or in excess of the copper sulphate,
that is, it will be neutralized, but if it is not, they will remain a
bright purplish red. Bordeaux mixture is used in strengths varying
from three to five pounds each of bluestone and lime in fifty gallons
of water, but the former is usually sufficient.
LIME-SULPHUR.--The more important fungicides, the commercial lime
sulphur and the self-boiled lime-sulphur, are practically superseding
Bordeaux as a fungicide, not because they are necessarily better, but
because there is frequently much burning of the foliage and russeting
of the fruit from the use of the Bordeaux. This is unfortunate as the
latter is a rather more effective fungicide as well as more convenient
and pleasant to use. The self-boiled lime sulphur is a combination of
lime and sulphur which is boiled by the heat of the slaking lime
alone, and makes a pretty good substitute for the Bordeaux when it
injures foliage or fruit. This preparation of lime and sulphur differs
from the commercial form used as a winter wash in that it is wholly a
mechanical mixture and not partly chemical like the latter. It may
therefore be used on the foliage in summer at a greater strength,
there being only a very small percentage of sulphur in solution when
the mixture is properly made.
Equal amounts of lime and sulphur are used, these being from eight to
ten pounds each to fifty gallons of water. The mixture is best
prepared in larger quantities so as to get heat enough from the
slaking lime to produce a violent boiling for a few minutes. First,
place say forty pounds of lime in a barrel and pour on just water
enough to start it slaking nicely--about a gallon to each three or
four pounds of lime is usually sufficient. Then add the sulphur and
enough more water to slake the paste, keeping it well stirred
meanwhile. The violent boiling of the lime in slaking will cook the
mixture in from five to fifteen minutes, depending on the quality of
the lime and how fast it is slaked. Just as soon as the violent
boiling is over add enough cold water to stop all action. If this is
not done, some sulphur will unite with the lime and burning may be the
result.
This self-boiled mixture is entirely harmless to apple foliage and
even appears to have a stimulating effect upon it. Against the apple
scab, however, it is not as effective as the boiled wash, or the
commercial preparations. For this disease a strength of from one to
thirty to one to forty (that is about one and one-half gallons of the
prepared mixture testing 31 to 33 Beaume to fifty gallons of water) of
the commercial lime-sulphur is most effective.
SPRAY PUMPS.--The application of the foregoing spray mixtures is fully
as important as the sprays themselves, for on the right application at
the right time depends the efficacy of the spray. For this purpose a
considerable amount of special machinery has been devised. Lack of
space prevents us from going into much detail on this question, so we
must be content with merely outlining the different types of machines
and mentioning their accessories. Sprays are forced through single,
double or triple acting pumps, either by hand or power. The three
types of power available are traction, compressed air, and gasoline,
the last being the most used. Steam power is practically obsolete.
The knapsack is the simplest type of hand pump, but it is of no
practical use in the mature apple orchard. For small orchards and
small trees several types of hand pumps are quite effective. The lever
type of pump, where the handle is pushed from and pulled toward the
operator, probably gives the most power with the least tiring effect,
because it enables one to use the weight of the body to some extent.
It is best not to have the pump attached to the spray barrel or tank,
but set on a movable base of its own, as then it can be used for any
one of a number of barrels. Such an outfit may be obtained for from
twenty-five to forty dollars.
It is well to buy a standard make of pump, preferably from a nearby
dealer, so that repairs may be readily secured. For all orchards up to
three or four acres in size, and for larger orchards where the trees
are not over twelve or fifteen feet in height, this kind of spray rig
is the most practicable and advisable, when the expense is taken into
consideration. This applies especially to the general farm.
The power of a traction sprayer is developed from the wheels. There is
much discussion as to whether sufficient power to throw an effective
spray can be supplied by this method. By accumulating considerable
pressure by extra driving at the ends of the rows and then skipping
every other tree in order to keep up the pressure, going over the rows
twice, a very satisfactory pressure can be obtained for trees which
are not too large. The argument for this type of machine, and it is
especially applicable on the general farm, is that it can be used for
other spraying on the farm as well as for the apple orchard,
especially for potatoes and small fruits. It is a comparatively cheap
type of power, particularly when it can be used for several purposes.
The compressed air gas sprayer comes next in point of simplicity and
cost for a power sprayer. Its most economic use is found where
orcharding is carried on extensively enough to pay to compress the air
or gas right in the orchard. This is of course impracticable on the
general farm. Therefore the air or gas must be purchased and shipped
to the farm in steel tubes. This often causes delay at critical times
and is rather expensive. Moreover, the gas is open to the objection of
interfering with the lime-sulphur compound by precipitating some of
the sulphur.
The gasoline engine is the most useful and popular type of power for
the orchard sprayer, as well as for general use on the farm. Many
makes are now so perfected that they give little or no trouble. One
and a half or two horsepower are fully sufficient for spraying, but
most farmers prefer from three to five horsepower in order to be able
to use the engine more for other purposes. The latter power is open to
objection for spraying purposes on account of its weight, as
especially in early spring it is very difficult to haul so heavy a rig
over the soft ground. Such an outfit is also rather expensive.
Standard makes of gasoline engines of sufficient power for spraying
cost from $75.00 to $150.00 according to horsepower and efficiency.
For very large trees, for mature orchards, and for all orchards larger
than four or five acres, the gasoline engine is the best source of
power for spraying, particularly where it can be used for other
purposes on the farm.
A double acting or two cylinder pump is most desirable. If there is
plenty of power a triplex or three cylinder pump is still better. The
requirements of a good pump are: sufficient power for the work desired
of it; strong but not too heavy; fewest possible number of parts
consistent with efficiency; brass parts and valves; and a good sized
air chamber. A number of standard makes of pumps answer these
conditions very well. Pumps should always be washed out with clean
water when the operator is through with them and the metal parts
coated with vaseline. Never leave water in a pump chamber or in the
engine jacket in cold weather.
The ordinary hand pump and barrel give satisfactory use when placed on
a wagon, unless the trees are very high. But for large orchards, high
trees, and where larger tanks and power pumps are used it is
desirable to have a special truck for the outfit. The front wheel
should be made low so as to turn under the tank to enable the driver
to make short turns around the trees. A tower is desirable where high
old trees are to be sprayed. This should be substantial but as small
as is consistent with the purpose so as not to catch on the limbs and
make it difficult to get close up around the trees. The height of the
platform must be regulated by the need and by the roughness of the
ground. On steep side hills the wagon body on which the tank rests
should be underslung.
In order to get as near to the work as possible get a long hose--from
twenty to thirty feet according to circumstances. The best quality,
three to five ply, is none too good. Hose should be three-eighths to
one-half inch in diameter, one inch being too heavy. Extension rods
are a practical necessity. They should be ten to twelve feet long and
made of bamboo lined with brass, that is, as light as possible.
Nozzles are very important in thorough and effective spraying. There
is no best nozzle, nor one with which all the work can be done.
Several things should be considered in selecting a nozzle. First of
all, it must be of convenient form so as not to catch in trees and so
constructed that it will not clog easily. Second, for apple trees it
should have good capacity and deliver as spreading a spray as
possible. Third, the nature of the spray is very important.
Insecticides should usually be applied with force in a comparatively
coarse driving spray, but fungicides should be applied in a fine mist
or fog so that they will settle on every part of the tree. Therein
lies the difficulty of applying insecticides and fungicides together.
TIME OF SPRAYING.--Fortunately it is not necessary to make a separate
application for each insect and disease, but they may be treated
together to some extent. In most cases expediency demands that the
arsenicals be used with the fungicides. Many growers are finding the
most satisfactory results, however, from applying the arsenical spray
separately, just after the blossoms fall, because of the physical
impossibility of properly applying the two sprays--the driving and the
mist spray--together. For most practical purposes on the general farm,
three sprayings are necessary in order to secure clean fruit and four,
sometimes five, are often advisable. These may be summarized as
follows:
1. With lime-sulphur, winter strength, on the dormant wood in
early spring.
2. With lime-sulphur and arsenate of lead just before the
blossoms open (may sometimes be omitted).
3. With the same (or Bordeaux for scab) just after the blossoms
fall.
4. With the same two or three weeks later.
5. With arsenate of lead eight or nine weeks later (may
sometimes be omitted).
(In the south and middle latitudes where bitter rot and apple
blotch occur two other sprayings may be necessary.)
6. With Bordeaux about eight or ten weeks after the blossoms fall.
7. Again with the same about two weeks later.
A Calendar for Spraying Apples
--------+--------+--------+--------+--------+-------+---------+----------
INSECTS | Nature | Before | Before | After | In 2 | In 8 | Materials
| of | Leaf | Flower | Petals | to 3 | to 9 | to
| Injury | Buds | Buds | Fall | Weeks | Weeks | Use
| | Open | Open | | | |
--------+--------+--------+--------+--------+-------+---------+----------
Codling | Eating | | | x | x | x | Lead
Moth | Worm | | | | | | Arsenate
| | | | | | | or
| | | | | | | Par. Gr.
--------+--------+--------+--------+--------+-------+---------+----------
San Jose|Sucking | x | | | | | Lime
Scale | Insect | | | | | | Sulphur
--------+--------+--------+--------+--------+-------+---------+----------
Oyster | Sucking| x | | | | | Lime
Shell | Insect | | | | | | Sulphur
Scale | | | | | | |
--------+--------+--------+--------+--------+-------+---------+----------
Blister | Leaf | x | | | | | Lime
Mite | Miner | | | | | | Sulphur
--------+--------+--------+--------+--------+-------+---------+----------
Plant | Sucking| | when seen | | | Whale Oil
Louse | Insect | | | | | | Soap or
| | | | | | | Tobacco
--------+--------+--------+--------+--------+-------+---------+----------
Cigar | Eating | | x | x | x | | Lead
Case | Insect | | | | | | Arsenate
Bearer | | | | | | | or
| | | | | | | Par. Gr.
--------+--------+--------+--------+--------+-------+---------+----------
Apple | Eating | x | x | | destroy fruit | Lead
Maggot | Worm | | | | | | Arsenate
| | | | | | | or
| | | | | | | Par. Gr.
--------+--------+--------+--------+--------+-------+---------+----------
Bud | Eating | x | x | x | | | Lead
Moth | Worm | | | | | | Arsenate
| | | | | | | or
| | | | | | | Par. Gr.
--------+--------+--------+--------+--------+-------+---------+----------
Curculio| Eating | | x | x | | | Lead
| Worm & | | | | | | Arsenate
| Beetle | | | | | | or Par. Gr.
--------+--------+--------+--------+--------+-------+---------+----------
=Diseases=| | | | | | |
--------+--------+--------+--------+--------+-------+---------+----------
Apple | Fungus | x | x | x | x | if | Lime
Scab | | | | | |necessary| Sulphur
| | | | | | | or
| | | | | | | Bordeaux
| | | | | | | 3-3.50
--------+--------+--------+--------+--------+-------+---------+----------
| | | | | | |
New York| Fungus | x? | cut out | | | Lime
Apple | | | infections | | | Sulphur
Tree | | | | | | |
Canker | | | | | | |
--------+--------+--------+--------+--------+-------+---------+----------
Leaf | Fungus | x | x | x | | | Lime
Spot | | | | | | | Sulphur
--------+--------+--------+--------+--------+-------+---------+----------
Sooty | | | | x | x | x | Bordeaux
Blotch | | | | | | | Mixture
| | | | | | | and Lime
| | | | | | | Sulphur
--------+--------+--------+--------+--------+-------+---------+----------