June ipip 



BETTER FRUIT 



Page p 



grower should be highly successful. 

 Since 1911, apple orchards in this sec- 

 tion have been in the stage of being 

 developed at a high cost, while the aver- 

 age production per acre has been low, 

 as the trees were too young to bear full 

 yields. This naturally resulted in a 

 high cost per box. It cost just as much 

 to care for an orchard that produced 

 100 boxes of apples to the acre as it did 

 to care for one that produced 500 boxes, 

 except in the harvesting; in addition to 

 the fact that the same amount of money 

 was invested. There has been the 

 drawback also that it has taken a num- 

 ber of years to determine the methods 

 to be used in all phases of orcharding 

 to secure the best results. In trying to 

 solve these problems, which included 

 not only growing, but packing, shipping 

 and selling, many thousands of dollars 



were spent by the grower that should 

 be saved in the future. Methods for 

 growing fruit successfully are now on 

 a fixed basis, while marketing is no 

 longer a matter of guess work from 

 year to year. The various marketing 

 channels that have been opened to the 

 grower give him the option of selling 

 his fruit by various methods. He now 

 knows just what he must do to produce 

 the best fruit at the least cost; just 

 what and how to pack. He has become 

 familiar with what the tj'ade will take 

 and has discovered that it doesn't pay 

 to attempt to throw on the big markets 

 of the East stock that is not up to grade. 

 In my observations in the apple- 

 growing districts of the Northwest, I 

 find that orchardmen are becoming 

 more and more a unit in using the most 

 progressive and up-to-date methods. 



They are watching everything con- 

 nected with the apple-growing industry 

 closely and where any feature can be 

 added that will tend to make the or- 

 chard pay better they are not slow in 

 taking it up. An example of this can 

 be found in growing alfalfa in orchards. 

 In the early stages of fruit raising it 

 was considered almost a crime to grow 

 anything in an orchard but trees. It is 

 now found that where there is irriga- 

 tion, alfalfa grown between the trees is 

 not only profitable but highly beneficial 

 in restoring nitrogen and humus to the 

 soil. 



It is these things combined with the 

 lesson that experience has taught the 

 Northwest orchardist, as well as the 

 buyer and shipper of Northwest fruit, 

 that forecast a greater success for the 

 industry in future. 



The Field Testing of Copper-Spray Coatings on Foliage 



By J. R. Winston, Assistant Pathologist, and H. R. Fulton, Pathologist, Office of Fruit-Disease Investigations 



GENERAL experience in the use of 

 copper-containing spray mixtures 

 indicates a progressive decrease 

 in the fungicidal effectiveness of the 

 spray coatings which is to a large extent 

 proportional to the relative amounts of 

 spray residue present. A direct de- 

 crease in effectiveness is brought about 

 by weathering factors, such as washing 

 by rain or dew, mechanical abrasion by 

 wind, and slow chemical change in the 

 exposed spray coating. An indirect de- 

 crease in effectiveness may result from 

 the growth extension of plant parts, 

 either through enlargement of organs 

 already sprayed or through the develop- 

 ment of new organs subsequent to the 

 spray application. In practice the in- 

 terval between spray applications de- 

 pends on the rates of both weathering 

 and growth extension. The second can 

 be judged by careful observation. In 

 so far as the first is concerned, observa- 

 tions are often misleading. Present- 

 day spray calendars are based only in 

 a general way on the average practical 

 and experimental experience of past 

 years. In any particular season or sec- 

 tion or planting the actual requirements 

 for adequate protection may vary 

 widely from such average, necessitating 

 greater or less frequency of application 

 than the standard spray calendar pro- 

 vides. It is difficult to estimate the 

 effects of the complicated set of local 

 factors that determine the effective 

 period of any spray application. A 

 suitable chemical test of the spray coat- 

 ing would seem to be a desirable aid in 

 forming judgment as to the proper time 

 for renewal. Such test should be 

 simple, rapid and reasonably accurate. 

 The more refined methods of chemical 

 analysis, while very exact, would not 

 well serve the practical purpose, be- 

 cause of the special requirements in 

 professional training, apparatus and 

 time. 



A Practical Method of Field Testing 



The following method has been used 

 during two seasons and has been found 

 to be reasonably satisfactory in field 

 practice. This is indicated by the con- 



sistent results obtained with varying 

 strengths of copper sprays, many of 

 which have been checked by exact 

 chemical analyses of duplicate samples. 



A 200-gram fresh weight sample of 

 leaves is washed at least three minutes, 

 with occasional stirring, in 1,000 c. c. of 

 a 0.2 per cent solution of chemically 

 pure nitric acid in water, either dis- 

 tilled or sufficiently pure to give correct 

 results. A convenient amount of this 

 acidulated wash water is treated with 

 a few drops of 2 per cent solution of 

 potassium-ferrocyanide solution, suffi- 

 cient to precipitate the copper. A color 

 comparison is then made with a series 

 of known dilutions of a standard cop- 

 per solution, similarly treated with the 

 potassium-ferrocyanide solution. From 

 this comparison the copper content of 

 the wash water is determined. For 

 more exact readings a colorimeter may 

 be used. 



The standard copper solution is made 

 by dissolving 3.928 grams of pure crys- 

 tals of copper sulphate in water to 

 make 1,000 c. c. Each cubic centimeter 

 of such standard solution would then 

 contain 1 milligram of copper, and by 

 proper dilution with water stock solu- 

 tions may be readily prepared for the 

 comparison series containing one-half 

 to 10 mg. of copper per 100 c. c. of 

 water, in one-half or 1 mg. grades. If 

 the wash water gives readings above 

 8 or 10 mg. of copper per 100 c. c. it 

 should be diluted for accurate color 

 comparison and account of this taken 

 in figuring results. On the basis indi- 

 cated above, any direct reading multi- 

 plied by 5 will express the amount of 

 copper in the spray residue in milli- 

 grams per 100 grams fresh weight of 

 leaves, a convenient unit for tabulation 

 purposes. The solutions of potassium 

 ferrocyanidc and of nitric acid may be 

 varied in strength for considerable dif- 

 ferences in the copper content of the 

 spray coating, so as to avoid using un- 

 necessarily strong solutions, willi con- 

 secjuent reduction in the delicacy of the 

 test. There must always be a sufficient 

 amount of nitric acid to dissolve com- 

 pletely the copper compounds and of 



potassium fcrrocyanide to precipitate 

 them completely. 



Due care must be taken to make the 

 leaf samples representative. About 

 three samples of 200 grams each should 

 be taken at various parts of a sprayed 

 planting. Under ordinary conditions 

 collections every three or four days 

 will give a satisfactory indication of the 

 persistence of the spray residue. If in 

 the case of any variety of leaf there is 

 a tendency toward discoloration of the 

 wash water from dissolution of organic 

 compounds in such a way as to inter- 

 fere seriously with the color com- 

 parisons, one may titrate a measured 

 quantity of the wash water with a solu- 

 tion of potassium fcrrocyanide pre- 

 viously standardized against a copper 

 solution of known strength, using a 

 weak ferric-chlorid solution as the end- 

 point indicator, in small drops on a 

 white porcelain plate. Tests on many 

 kinds of crop plants indicate that this 

 titration method will be seldom needed. 

 Permitting the weighed leaves to dry or 

 to "heaf may interfere with accurate 

 testing. 



The coating on the foliage will usu- 

 ally prove to be a fair index to the thor- 

 oughness of application to other parts. 

 For convenience, the samples are based 

 on weight, but the spray coating is pro- 

 portional to area. The different ratios 

 between these, due to difference in 

 species or age of leaves, when consid- 

 erable, should be given due weight in 

 making comparisons. Obviously, it is 

 possible to secure as high tests from 

 strong sprays unevenly applied as from 

 moderate strengths more evenly and 

 effectively used, but it is believed that 

 the histories of such cases will guard 

 against incorrect interpretations. 



The amount of spray residue neces- 

 sary for adequate protection against 

 any specific disease would doubtless 

 vary with a complex set of factors. 

 There would thus exist a critical transi- 

 tion zone with maximum and minimum 

 limits above which protection would be 

 secured and below which protection 

 would be insufiicient. These limits can 



Continued on page 31. 



