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When to Spray.
insects which chew the leaves or shoots, such as the codlin-moth, bud-moth, canker-worm, potatobeetle, tent-caterpillar, and the like. Kerosene emulsion is used for scale-insects and plant-lice. Bordeaux mixture and ammoniacal carbonate of copper are used to prevent the attacks of fungous parasites, as apple-scab, leaf-blight of the pear, quince and plum, potato-blight, and such like. Bordeaux is the better all-round fungicide, but the copper carbonate solution does not discolor the fruit, and may therefore be used if very late sprayings are necessary.
The times and seasons of spraying depend entirely upon the enemies which it is desired reach, and upon the weather.
8. The time to spray must be determined for each particular case. The grower himself must decide when and how often to spray, because he should
Boiling water (preferably soft water).
1 gallon ..2 gallons
Dissolve the soap in the water, add the kerosene, and churn with a pump for 5 to 10 minutes. Dilute 4 to 25 times before applying. Use strong emulsion (diluted 4 to 9 times) in winter for scale insects. For plant-lice, mealy bugs, red spider, thrips, weak preparations will prove effective. Cabbage worms, currant worms, and all insects which have soft bodies, can also be successfully treated. It is advisable to make the emulsion shortly before it is used.
† AMMONIACAL COPPER CARBONATE.
Before making the solution, the ammonia should be prepared as follows: Use 26° ammonia, and dilute with 7 to 8 volumes of water. Then gradually add the necessary amount to the copper carbonate until all is dissolved. It is best treated in large bottles, and in them it will keep indefinitely. Dilute as required. For same purposes as the Bordeaux mixture.
know what enemies he desires to reach. If he has the bud-moth, he should spray with the first swelling of the buds, and if he has the plum-scale he should spray in the winter. But, leaving the special insects aside, it is safe to say that for the two staple enemies - the apple-scab and the codlin - moth - at least two sprayings should be given. It is not yet clearly proved that spraying when the tree is dormant has any appreciable effect in destroying the apple-scab fungus. As a general statement one may say, spray twice upon apples and pears, once just as the fruit-buds break open but before the flowers ex
pand (Fig. 76), and again just as the last blossoms fall. In both cases, use a combination of Bordeaux mixture and Paris green. The first spraying is for the scab fungus in particular, and for this the Bordeaux is used; but the Paris green will most likely be of service in destroying various leaf-eating insects. The second spraying is for the codlin-moth in particular, and for this the Paris green is used; but the Bordeaux mixture will still be needed for the apple-scab and other fungi. Whether or not it is necessary to spray again will depend largely upon the season.
Fig. 76. Showing when apple trees are ready for the first spraying.
The operator must watch matters closely, and spray when he needs to do so, or when he is in doubt. Two sprayings are sufficient for the codlin-moth, and three are generally sufficient for the apple-scab. These two sprayings constitute the insurance which has been mentioned; thereafter, the grower will be able to see more definitely what is needed. These remarks illustrate the nature of the questions which the fruit-grower must consider.
At any time when the tree is in growth, Paris green or London purple should be used with lime, or, better, with Bordeaux mixture, to prevent injury to the foliage. One pound of Paris green to two hundred gallons of water is the most serviceable general formula for that material; and to this a pound or two of lime may be added. A pound of Paris green (or London purple) may be added to two hundred gallons of Bordeaux mixture. If the Paris green is made into a paste with a little water, it mixes better in the barrel.
9. Prepare stock solutions for the Bordeaux mixture, rather than to make each batch in the quantities
*NORMAL OR 1.6 PER CENT BORDEAUX MIXTURE.
..4 pounds 40-50 gallons
Dissolve the copper sulfate by putting it in a bag of coarse cloth and hanging this in a vessel holding at least six gallons, so that it is just covered by the water. Use an earthen or wooden vessel. Slake the lime in an equal amount of water. Then mix the two and add enough water to make forty gallons. It is then ready for immediate use. If the mixture is to be used on peach foliage, it is advisable to add two pounds of lime in the above formula. When applied to such plants as carnations or cabbages, it will adhere better if about a pound of hard soap be dissolved in hot water and added to the mixture.
called for by the formula.-The sulfate of copper may be put into solution and kept in this condition indefinitely, ready for use. A simple method is to dissolve forty or fifty pounds of sulfate in as many gallons of water, pulverizing the material and hanging it in a coffee-sack in the top of the barrel. A gallon of water, therefore, means a pound of sulfate. The lime may also be slaked and kept in readiness for use. Slake it into the creamy condition familiar to masons, cover lightly with water, and then close the box or vessel to prevent the water from evaporating. When making the Bordeaux mixture, pour the requisite quantity of the stock solution of sulfate of copper into the barrel, and then dilute with four or five times the quantity of water. Now add the lime, and then add enough water to satisfy the formula. If the ferrocyanide test is used, place a spoonful of the mixture in a sau cer or plate, and add a drop of the test olution. If a red color appears, the mixture needs more lime. If the test solution is added directly to a tank or barrel of the mixture, the color reaction is apt to be lost in the mass. An excess of lime ensures the safety of the mixture.
10. How can one tell if soluble arsenic is present in Paris green?-It is the soluble arsenic which burns the foliage. This is present in London purple, but good Paris green should have little of it. Farmers are always asking how they can determine if Paris green contains soluble arsenic. This may be determined by the use of the sulfur test. This
Testing Paris Green.
test consists in adding sulfuret of hydrogen to a solution of the poison, when, if arsenic is present, a yellow precipitate (or sediment) will be thrown down.
In a bottle holding five or six ounces, place a quarter of a teaspoonful of Paris green. Add water until the bottle is nearly full; shake well, and then allow the material to settle. The clear liquid which remains on top will contain what soluble arsenic may be present. Carefully turn off this clear liquid into a long, slender bottle, or test-tube, add two or three drops of muriatic or sulfuric acid, then add a tablespoonful or more of the solution of sulfuret of hydrogen. If any arsenic is present in the clear liquid, a yellow discoloration will at once appear, and if the liquid is allowed to stand for a few minutes, patches or grains of a sand-like material will settle to the bottom. This yellow precipitate is sulfide of arsenic. If very little soluble arsenic is present, the sulfuret solution should be warm when used, for the reaction is then more delicate. The sulfuret is easily made by anyone who has had even an elementary instruction in chemistry, by adding sulfuric acid to iron pyrites.
This sulfuretted hydrogen is not a commercial preparation, but it is present in all sulfur mineral water, and the water sometimes gives the test. One can make sure of the presence of this material, for its odor is strong and offensive. It is the odor of spoiled eggs. If mineral water is used, it should be strong and fresh, and about equal in quantity