OCR Text |
Show rlelpful Articles for the Farmer and Stockraiser Prepared for the Headers of this Paper by Professors at. the Utah Agricultural College DORMANT SPRAYING Dormant spraying is directed against those pests which may be most effectively ef-fectively controlled during their resting rest-ing stage. The absence of foliage in winter permits a more thorough application ap-plication and the use of stronger Insecticides In-secticides than would be safe on tress in leaf, graying may be done any tun after the leaves drop in the fall, or in winter when the weather warms up to 40 F.. but is preferable in early spring when the buds are swelling as at that time Insects become active and the spray is more fatal to them. All sprays used on dormant trees kill insects by contact rather than by poisoning them through the digestive tract. Fvt this purpose many sub-stancts sub-stancts are used, all of which either Interfere with the insect's breathing or corrodes its body, or both. Those commonly used for dormant spraying are lime-sulphur, kerosene or other miseible oils and soap sprays used undiluted un-diluted or in emulsion. Of these the lime-sulphur is disagreeable dis-agreeable to prepare and use; it spreads and penetrates poorly, but is safe, efficient, and has become the standard dormant spray because of its wide range of usefulness in controlling con-trolling nearly all insects that other dormant sprays control. It remains en the trees in an active condition extending its usefulness into the summer sum-mer as a destroyer of insects, fungi, and lichens which otherwise infest them. Nothing is more effective in controlling San Jose scale and many related scale Insects, the peartree psylla, blister-mite, spider mite, and several other pests. For those with small orchards it will probably always be cheaper and better to use the commercial product, being careful to follow accompanying directions ; however lime-sulphur may be prepared satisfactorily as follows : Use 5 lbs. fresh stone lime (90 or (commercial ground) ; about 5 gallons more, calcium oxide) ; 10 lbs. sulphur of water. Place a gallon of water in the cooking vessel and start heating it; the lime and sulphur is then placed in the vessel (the sulphur may be made to a paste to avoid lumpi-ness), lumpi-ness), as most convenient. Stir them vigorously while the lime is slacking. Add water as required to slack the lime properly until the five gallons are used. Boil about 50 minutes, stirring stir-ring frequently, after which the solution solu-tion should be of . amber color. The total yolume of the finished product should be 5 gallons. After straining out all insoluble material this stock solution can be kept indefinitely if flir is excluded from it. For accurate work with lime-sulphur a Baume hydometer to indicate the concentration is a necessity. The formula form-ula given should yield a solution about 26 Baume and for spraying San Jose Scale should be used one part to five of water. By using the same formula with but as much water the finished product will be more concentrated and should measure 3 gallons and have a concentration of about 33 Baume. For use dilute this strength one part to seven of water. These strengths are for San Jose scale and are too strong except for dormant trees. Where aphids are troublesome it in often practicable to delay the dormant dor-mant spraying until just as the buds are breaking, and, by adding forty per cent Nicotine Sulphate to the lime-sulphur at the rate of three-fourths three-fourths pint per 100 gallons of spray, effect a combination treatment for both scale and aphids. In order to be successful spraying must always be done throughly. It Is necessary to reach every part of the trees and for many of lour worst pests the application must be made at a definite and often limited time. The fruit grower owes it-to himself to study the pests affecting his trees sufficiently to enable him to intelligently intelli-gently combat them. |