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Spraying Machines. —A spraying outfit consists of a pump, nozzle, agitator, tank rods, hose, crop-spraying attachments, etc. They are made in various sizes, and are known as knapsack, carried and worked by a man; barrel, hauled by man or horse (Fig. 42), and worked by manual labor; and power sprayers, in which the pumping is done by gearing from the wheels, steam
FIG. 42-A SUGGESTIVE ENGLISH SPRAYING MACHINE Emphasis is laid upon coating the under surface of the leaves, and experi
ments show that it is profitable to do so under British conditions.
or gas engines, compressed air or carbon dioxid. The pressure is generated in the pump; 100 to 120 pounds pressure per square inch gives a much finer spray than 50 to 60 pounds. The power sprayers give the former, the manual labor sprayers rarely exceed the latter. The working parts of the pump should be of brass or bronze; rubber or leather valves, or any parts that Bordeaux mixture will corrode, are inadmissible. The pump should be easy to clean.
The nozzle and the pressure determine the character of the spray. The Vermorel type of nozzle is one of the best; it does good work at a low pressure of 50 to 60 pounds, but better work at 100 pounds. It does not throw the spray a great distance. The nozzle used should permit of being readily cleaned.
The agitator may be (1) mechanical or (2) the jet type. The former is generally used and considered more efficient, dashers being used in barrel outfits and whirling paddles in large tanks. The jet type returns a stream of solution from the pump to the bottom of the tank. It can be made efficient on power sprayers, but deficiency of power bars their use on hand outfits.
Tanks.—Cypress, pine, and cedar are used in making tanks, the first being considered best. Their capacity varies from 50 to 250 gallons.
Hose.—The hose should withstand a pressure of 125 pounds per square inch. Three and four ply are most used. Some prefer five and six ply. Half-inch hose is most commonly used; some prefer three-eighths of an inch.
Crop-spraying Attachments.—The potato spraying attachment should carry two or more nozzles for each row. These should be capable of being turned upward when not in use, to prevent their clogging with sediment while drying. The spray should be thrown upward and sideways, to coat the under surface of the leaves as well as the upper surface. From two to six rows are sprayed at a time (see Frontispiece and Fig. 42), and the attachment should fold or turn up to
facilitate turning or going through a gateway. Stationary nozzles cannot direct the spray so well as hand nozzles; hence, more should be put on to make sure that the plants are coated. The cost of the extra amount of mixture is small compared with the cost of the labor used in applying it.
Digging.-Early potatoes may be dug as soon as large enough. For late varieties which are to be stored it is necessary to wait until the tubers have attained full size, the haulm and leaves have died, the tubers come freely from the stem and have not to be jerked off, and the skins are firm and will not come off easily when rubbed. If the vines have been destroyed by blight the potatoes should not be dug until at least ten days after the vines are dead, as there is then less liability of rot in storage. If frost sets in early and the growing season has been late, it may be necessary to dig before the potatoes are quite mature. In this case the shrinkage in weight, if stored, will be greater than if they had matured, and a reasonable offer for them straight from the field should not be declined. For storage, potatoes must be dug when dry, picked up at once, and kept cool. If possible, haul to some cool place at once, and let them cool all night before placing in storage. This is impossible where large 1 quantities are grown, and in such cases good ventilation of the storage-place must be given to reduce thą temperature as quickly as possible.
Methods of Digging.-1. By Fork, Spade, or Potato-hook. — The early potatoes are often dug by hand because they are so easily injured. The skin is
i Vt. Bul. 106, p. 233.
tender, the tubers adhere to the stem, and often require removal. It is a slow, tedious process, but nearly every potato is obtained. A man will dig one-eighth to three-eighths of an acre a day. With the main crop a man will dig from one-tenth to one-half acre a day at a cost generally varying between two and six cents per bushel, sometimes running to eight and occasionally lower than two cents, depending a great deal on the skill of the man, the yield, the soil, and state of the land. As weather conditions may retard digging, and labor is hard to obtain, this method is being discontinued except on small patches.
2. Plow.—Plowing out with a common plow, or a potato plow, or so-called “digger,” many of which are:
Modified Shovel Plows.—All that I have tested have been failures. They dig some of the potatoes out and cover some up. On harrowing after them many more potatoes appear, and on digging the rows some may still be found. My experience has been that the potatoes left in would more than pay for digging by hand. They may be useful for small growers on a light soil, and for those who, being short of labor, wish to save part of their crop. Six to ten hands and two horses will dig one and a half to two acres per day. In the Southern States early potatoes are plowed out, and ten cents per barrel is paid for picking them up.
3. Mechanical Diggers.— The high-priced horsepower diggers, as the “Reuther” (Fig. 43), the “Hoover” (Fig. 44), and the “Dowden,” are all reported as satisfactory machines. They work on the same principle. The shovel-point is forced under the