UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION CIRCULAR No. 244 June, 1922 CENTRAL WIRE BRACING FOR FRUIT TREES By L. C. BARNARD During the past few years the Agricultural Experiment Station has tested the use of wire braces as a substitute for wooden props to support the limbs of fruit trees. The efficiency of wire braces and the methods of applying them have been studied in the Experiment IKS ^^1 BiSHfiKv m ' &£ m^PH Bracing fruit trees by means of wiring, Experimental Orchard, University Farm, Davis, California. (Frontispiece.) Z UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Station orchards and also in a number of commercial orchards, in cooperation with leading fruit growers. Wire braces have proved so satisfactory that they have aroused widespread inquiry. THE WIRE BRACE As shown in figures 1 and 7 the tree is braced from within by means of wires. Each limb is supported by a wire, one end of which is attached to the inner side of the limb by means of a screw eye or staple. The other ends of the wires come together in the center of the tree where they are attached to a single ring at the proper height (see fig. 1). Fig. 1. — Looking down on system of wire bracing in a prune tree. Note taut- ness and number of wires used, representing wooden props. METHOD OF BRACING In preparing to brace trees in this way approximately 150 to 200 feet of the wire should first be uncoiled along the row of trees to be wired, so as to be drawn toward the worker as he goes from tree to tree. A small branch or weight should be attached to the farther end to prevent recoiling and kinking. On the other end is made a tem- porary hook which is fastened to any convenient twig in reach of the worker when on the ladder. About a dozen washers or rings may be Fig. 2. — Showing wires fastened to ring in a very slipshod manner. Compare this tie with the one in figure 3 for neatness, economical use of wire, and possibili- ties for pulling out under a strain. Fig. 3. — Showing japanned harness ring, also six figure eight ties, same as used on hay balers. Note neatness of tie, also economical use of wire. Will not pull out. 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION carried on a wire hook attached to the belt. Pliers, staples, screw eyes, hammer, and awl should be accessible for rapid work. The operator is now ready to ascend the ladder which is set in the center of the tree as shown in the frontispiece. A screw eye or staple is inserted on the inner side of each of the four or five main limbs. The smaller branches may in turn be wired to the main limbs. The staple or screw eye should be inserted at the proper height. If placed too low on the limb the latter may break above the support ; if placed too far out on the limb there is a tendency to pull the ends of the branches in, giving the tree a bowed appearance. An awl may be used to puncture the limb for insertion of the screw eye. The screw eye should be screwed down until its lower side just touches the bark and is left parallel to the limb rather than cross- wise ; if left crosswise it might cause restriction of the sap flow. This caution also applies to the position of staples when they are used. After the screw eyes are in place, the hooked end of the uncoiled wire is inserted through one of the eyes and securely twisted to pre- vent slipping or pulling out. The ordinary figure eight tie, as used on hay balers, is recommended (see fig. 2). After tying, the wire is drawn toward the center and cut the desired length. From a screw eye on the opposite side of the tree the same operation of wiring is repeated. A washer, or harness ring, is next secured to the loose end of a wire that has been fastened to a screw eye. With this washer or ring in one hand the loose end of the second wire is directed through the washer or ring, pulled taut, and twisted securely. The wires should not be pulled too tight nor left too loose; they should simply take up the slack of the branches induced by gravity. The ring is now suspended in the center of the tree by the wires from opposite screw eyes and it is easy to attach the other wires. NUMBER OF TREES WIRED PER DAY The number of trees which may be wired in a day depends on the size of the tree and whether staples or screw eyes are used, more time being required to insert the latter. About 35 to 40 large peach trees have been wired by the writer in nine hours. In one orchard of French prune trees, twenty to thirty years old and heavily loaded, many so large as to require a double tier of wires, only 20 to 25 trees could be wired by two men, one man working in the center of the tree and the other around the outside. Circular 244] CENTRAL WIRE BRACING OF FRUIT TREES TIME OF YEAR TO WIRE TREES If wired while the crop is on the tree, the worker cannot see well ; also there is some loss of leaves and fruit. The fact that the wood is soft, however, facilitates the work with the screw eyes or staples. If wired in the fall when the leaves are off, after pruning, not only can the worker see better, but wires will not be placed on limbs which may be pruned out later. At this season the limbs are in normal position, are not weighted down with fruit, and do not need propping before securing the wire to the ring. The time of wiring may depend upon a number of factors, like grower's time, condition of the trees, urgent necessity of support, number of props on hand for the season, cost of material, and labor available. Fig. 4. — Showing wire leading to screw eye which has finally grown over by succeeding layers of growth. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION YOUNG TREES MAY REQUIRE REWIRING LATER Trees which are wired at an age of from four to eight years may later require additional wiring. In the case of tall trees a second tier of wires is sometimes advantageous. ADVANTAGES OF WIRE BRACING SHOWN BY COMPARISON Wire Bracing 1. Practically permanent, lasting from 20 to 30 years. 2. Cost of material for wiring a tree is comparatively cheap and the depreciation is very low. 3. Wiring can be done at almost any season of the year. 4. Wire bracing does not interfere with tillage and is not affected by irrigation. 5. An orchard with trees centrally wired does not make an unattractive appearance. 6. With wire bracing the strain on any one limb is supported by all limbs, and during wind storms the braces are secure. 7. Wire bracing does not interfere with harvesting. Wooden Props 1. Props usually last only from three to five years, and must be stored when not in use. 2. The cost of material for prop- ping is expensive and the depreciation high. 3. Wooden props must be placed under the limbs during the fruiting season. 4. Wooden props are a great incon- venience in cultivating and often settle or fall during irrigation, allowing limbs to break. 5. An orchard with several thou- sand wooden props is unsightly. 6. Each limb is supported separ- ately and is allowed to whip in the wind, props being often dislodged. 7. Wooden props are inconvenient because a fruit picker must continu- ally dodge and move his ladder around them; they are also in the way of the orchard truck. EQUIPMENT NECESSARY AND COST OF MATERIAL Ladders (small or large), hammer, pliers, staples or screw eyes of various sizes, %" iron washers (inside diam.), V/2" japanned malleable iron harness rings, galvanized wire of various calibres, preferably No. 14. Circular 244] CENTRAL WIRE BRACING OF FRUIT TREES Though prices may vary several times during any one year, the following quotations, obtained in November, 1921, may be of value as a basis for estimating the cost of materials used in wire bracing. Galvanized wire No. 14 (approx. 250 lbs.) $17.67 per coil Screw eyes, No. 107, (large eye) .72 per gross Screw eyes, No. 209, (small eyes) .72 per gross Screw eyes, No. 108 (smaller caliper) .75 per gross Harness rings (japanned malleable iron), 1^" 3.25 per gross Harness rings (japanned malleable iron), l 1 /^" 2.25 per gross Harness rings (japanned malleable iron), 1" 1.40 per gross Iron washers (inside diam. %") .12 per lb. Staples, %" to 2" .07 per lb. Galvanized wire, No. 14 — 1 coil or 250 lbs., approx. 14,625 ft. Iron washers, %" size 12 per lb. Staples, %" size 416 per lb. Staples, 1" 108 per lb. Staples, \V±" 87 per lb. Staples, iy 2 " 72 per lb. Staples, 1%" 72 per lb. Staples, 2" 58 per lb. Fig. 5. — A heavily loaded Robe de Sargeant prune tree wire braced. UNIVERSITY OF CALIFORNIA EXPERIMENT STATION COMPARATIVE COST Material. — Assuming that a full-bearing tree of average size re- quires at least eight props and that the minimum life of wire braces is 20 years, and that of the props three years, the comparative cost of propping and wiring, at current prices of materials, is as follows : Wire Bracing No. 14 gal. wire = 58' per lb. 8 wires 5' long = 40' @ 7c per lb. $.05 8 screw eyes @ 72c per gross 04 1 harness ring @ $3.25 per gross .02 Cost per tree, 20-year period $.11 Wooden Props 8 props 1" X 2" X 10' @ $40 per thou. (M) equals 13:3 @ 4c = $ .55 per tree. For a 20-year period the cost for wooden braces would be $3.66 per tree. Fig. 6. — Propped Robe de Sargeant prune tree in same block as tree in fig. 5. Note number of wooden props used and the amount of space not accessible to orchard operations. Circular 244] CENTRAL WIRE BRACING OF FRUIT TREES 9 Labor. — Wooden props, for any one year, can be more quickly installed than wire braces; the labor cost for a single season would therefore be less. Over a twenty-year period, however, the cumulative cost of wooden propping would greatly exceed that of wiring, con- sidering that the props must be hauled into and out of the orchard each year. HELPFUL HINTS 1. For convenient work the ladder should be set up in the center of the tree. (See frontispiece.) 2. A tough leather glove worn on the hand used in twisting the wire is of considerable help. 3. It is a less serious mistake to place the wires too high than too low. If placed too low, breakage occurs above the screw eye or staple. 4. Staples can be more quickly installed than screw eyes. The ordinary barbed wire staples are best for the main limbs. Small chicken wire staples should not be used for the main limbs, as they will pull out. 5. After starting the screw eye, time can be saved by putting the point of the awl through the eye and using it as a lever to twist the screw eye into place. 6. When staples are used they should be driven in as far as pos- sible, thus allowing the wounds to heal over sooner. 10 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION Fig. 7. — Showing wire bracing system supporting the weight of the worker. Photograph of wired peach tree in experimental orchard, Davis, California. STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION BULLETINS No. 185 241. 246. 251. 253. 261. 262. 263. 266. 267. 268. 270. 271. 273. 275. 276. 278. 279. 280. 282. 283. 285. 286. 287. 294. 297. 298. Report of Progress in Cereal Investiga- tions. Vine Pruning in California, Part I. Vine Pruning in California, Part II. Utilization of the Nitrogen and Organic Matter in Septic and Imhoff Tank Sludges. Irrigation and Soil Conditions in the Sierra Nevada Foothills, California. Melaxuma of the Walnut, "Juglans regia." Citrus Diseases of Florida and Cuba Compared with Those of California. Size Grades for Ripe Olives. A Spotting of Citrus Fruits Due to the Action of Oil Liberated from the Rind. Experiments with Stocks for Citrus. Growing and Grafting Olive Seedlings. A Comparison of Annual Cropping, Bi- ennial Cropping, and Green Manures on the Yield of Wheat. Feeding Dairy Calves in California. Preliminary Report on Kearney Vineyard Experimental Drain. The Cultivation of Belladonna in Cali- fornia. The Pomegranate. Grain Sorghums. Irrigation of Rice in California. Irrigation of Alfalfa in the Sacramento Valley. Trials with California Silage Crops for Dairy Cows. The Olive Insects of California. The Milk Goat in California. Commercial Fertilizers. Vinegar from Waste Fruits. Bean Culture in California. The Almond in California. Seedless Raisin Grapes. No. 299. 300. 304. 308. 309. 310. 312. 313. 316. 317. 318. 320. 321. 323. 324. 325. 328. 330. 331. 332. 334. 335. 336. 337. 339. 340. The Use of Lumber on California Farms. Commercial Fertilizers. A Study on the Effects of Freezes on Citrus in California. I. Fumigation with Liquid Hydrocyanic Acid. II. Physical and Chemical Pro- perties of Liquid Hydrocyanic Acid. I. The Carob in California. II. Nutritive Value of the Carob Bean. Plum Pollination. Mariout Barley. Pruning Young Deciduous Fruit Trees. The Kaki or Oriental Persimmon. Selections of Stocks in Citrus Propagation. The Effects of Alkali on Citrus Trees. Control of the Coyote in California. Commercial Production of Grape Syrup. Heavy vs. Light Grain Feeding for Dairy Cows. Storage of Perishable Fruit at Freezing Temperatures. Rice Irrigation Measurements and Ex- periments in Sacramento Valley, 1914- 1919. Prune Growing in California. Dehydration of Fruits. Phylloxera-Resistant Stocks. Walnut Culture in California. Preliminary Volume Tables for Second- Growth Redwoods. Cocoanut Meal as a Feed for Dairy Cows and Other Livestock. The Preparation of Nicotine Dust as an Insecticide. Some Factors of Dehydrater Efficiency. The Relative Cost of Making Logs from Small and Large Timber. Control of the Pocket Gopher in California. CIRCULARS No. No. 70. Observations on the Status of Corn 165. Growing in California. 82. The Common Ground Squirrels of Cali- 166. fornia. 167. 87. Alfalfa. 169. 110. Green Manuring in California. 170. 111. The Use of Lime and Gypsum on Cali- fornia Soils. 172. 113. Correspondence Courses in Agriculture. 173. 115. Grafting Vinifera Vineyards. 174. 126. Spraying for the Grape Leaf Hopper. 175. 127. House Fumigation. 128. Insecticide Formulas. 176. 129. The Control of Citrus Insects. 130. Cabbage Growing in California. 177. 135. Official Tests of Dairy Cows. 178. 138. The Silo in California Agriculture. 179. 144. Oidium or Powdery Mildew of the Vine. 148. "Lungworms." 181. 151. Feeding and Management of Hogs. 182. 152. Some Observations on the Bulk Handling of Grain in California. 183. 153. Announcement of the California State 184. Dairy Cow Competition, 1916-18. 188. 154. Irrigation Practice in Growing Small 189. Fruits in California. 190. 155. Bovine Tuberculosis. 193. 157. Control of the Pear Scab. 198. 158. Home and Farm Canning. 201. 159. Agriculture in the Imperial Valley. 202. 160. Lettuce Growing in California. 161. Potatoes in California. 203. 164. Small Fruit Culture in California. 205. Fundamentals of Sugar Beet Culture under California Conditions. The County Farm Bureau. Feeding Stuffs of Minor Importance. The 1918 Grain Crop. Fertilizing California Soils for the 1918 Crop. Wheat Culture. The Construction of the Wood-Hoop Silo. Farm Drainage Methods. Progress Report on the Marketing and Distribution of Milk. Hog Cholera Prevention and the Serum Treatment. Grain Sorghums. The Packing of Apples in California. Factors of Importance in Producing Milk of Low Bacterial Count. Control of the California Ground Squirrel. Extending the Area of Irrigated Wheat in California for 1918. Infectious Abortion in Cows. A Flock of Sheep on the Farm. Lambing Sheds. Winter Forage Crops. Agriculture Clubs in California. A Study of Farm Labor in California. Syrup from Sweet Sorghum. Helpful Hints to Hog Raisers. County Organizations for Rural Fire Con- trol. Peat as a Manure Substitute. Blackleg. CIRCULARS — Continued No. 206. Jack Cheese. 208. Summary of the Annual Reports of the Farm Advisors of California. 209. The Function of the Farm Bureau. 210. Suggestions to the Settler in California. 212. Salvaging Rain-Damaged Prunes. 214. Seed Treatment for the Prevention of Cereal Smuts. 215. Feeding Dairy Cows in California. 217. Methods for Marketing Vegetables in California. 218. Ad -,• anced Registry Testing of Dairy Cows. 219. The Present Status of Alkali. 220. Unfermented Fruit Juices. 221. How California is Helping People Own Farms and Rural Homes. 223. The Pear Thrips. 224. Control of the Brown Apricot Scale and the Italian Pear Scale on Deciduous Fruit Trees. No. 225. Propagation of Vines. 227. Plant Diseases and Pest Control. 228. Vineyard Irrigation in Arid Climates. 229. Cordon Pruning. 230. Testing Milk, Cream, and Skim Milk for Butterfat. 231. The Home Vineyard. 232. Harvesting and Handling California Cherries for Eastern Shipment. 233. Artificial Incubation. 234. Winter Injury to Young Walnut Trees During 1921-22. 235. Soil Analysis and Soil and Plant Inter- relations. 236. The Common Hawks and Owls of Cali- fornia from the Standpoint of the Rancher. 237. Directions for the Tanning and Dressing of Furs.