Page 28 



be seen that this field was rtally pro- 

 tected for only 3 out of 38 days by six 

 applications. 



Field B, with two applications, 

 dropped below the theoretical transi- 

 tion zone 10 days after the second appli- 

 cation and stood with insufficient pro- 

 tection during the remaining fifteen 

 days of the test period. 



Field C, with four applications, was 

 insufficiently protected during a total of 

 five days, but this could have been pre- 

 vented by slight shortening of the in- 

 tervals between applications. 



Field D was late celery sprayed first 

 on March 1. On the basis of the limits 



BETTER FRUIT 



assumed for the critical zone, the sec- 

 ond application should have followed 

 the first in ten days, and the interval 

 between the third and fourth might 

 have been considerably prolonged pro- 

 vided large growth development had 

 not occurred. 



Directions for Use 



As a guide in the practical use of this 

 method, a condensed statement of the 

 successive steps may be outlined, as 

 follows: 



Dissolve 3.928 grams of pure crystals 

 of copper sulphate in distilled water 

 and make up to 1,000 c. c. 



Ridley,Houlding&Co. 



COVENT GARDEN, LONDON 



WE ARE 



Specialists in 

 Apples and Pears 



CABLE ADDRESS: BOTANIZING. LONDON 



Codes: A. B. C. 5th Edition and Modern Economy 



Dependable 



"Red Crown" is straight-distilled, 

 all-refinery gasoline. Look for the 

 Red Crown sign before you fill. 



STANDARD OIL COMPANY 

 (California) 





WHEN WRITING ADVERTISERS MENTION BETTER FRUIT 



June igiQ 



Prepare in well-stoppered bottles 

 stock dilutions of the above solution 

 containing one-half c. c, 1 c. c, 1% c. c, 

 2 c. c, and so on up to 10 c. c. in 100 c. c. 

 of distilled water. These dilutions would 

 then contain from one-half to 10 milli- 

 grams of copper per 100 c. c. 



Prepare a weak solution of potassium 

 ferrocyanide, about 2 grams in 100 c. c. 

 of distilled water. 



All of the above may be preparetl in 

 advance, by a pharmacist if desirable, 

 and kept for a season's use. 



Collect at least three representative 

 samples of sprayed leaves, each of 200 

 grams fresh weight. 



Wash each sample separately in 1,000 

 c. c. of pure water to which has been 

 added 2 c. c. of chemically pure nitric 

 acid, being careful to use glass or 

 chinaware vessels and stirring occa- 

 sionally for at least three minutes. 



Pour into test tubes or vials of uni- 

 form size about 5 c. c. portions of the 

 graded stock solutions of copper sul- 

 phate, and add to each a few drops of 

 the potassium - ferrocyanide solution, 

 sufficient to develop the maximum color 

 reaction. 



Treat similarly 5 c. c. portions of the 

 washings from the leaf samples. Com- 

 pare the color developed in these with 

 the graded series. Take for a reading 

 the number expressing milligrams of 

 copper per 100 c. c. in the stock dilution 

 that matches closest in color intensity. 

 Simply multiplying this reading by 5 

 will then give a value in milligrams of 

 copper per 100 grams fresh weight of 

 leaf sample, a convenient unit for 

 finally expressing the amount of copper 

 in the spray coating. The results from 

 the several samples may be compared 

 and averaged. 



Conclusion 



This field method of following the 

 persistence of copper-containing sprays 

 promises to be of service to pathological 

 investigators, agricultural experts and 

 commercial growers along these lines: 

 (1) To secure data showing the per- 

 sistence of copper-containing sprays as 

 it may be influenced by method of 

 preparation, weathering, or other fac- 

 tors; (2) to determine the minimum 

 and maximum limits of working safety 

 zones, as measured by evenly dis- 

 tributed residues, effective for the prac- 

 tical control of specific diseases; (3) to 

 secure prompt correction of faulty 

 spraying practices, either in the prepa- 

 ration of mixtures or in the times or 

 modes of application, with a view to 

 insuring more effective and economical 

 protection of crops; and (4) to serve as 

 a practical guide in timing new appli- 

 cations, especially after rainy periods. 



Wenatchee Buys Many Orchard Ladders 



A single order for 5,750 feet of or- 

 chard ladders has been placed by the 

 Wenatchee Produce Company, who are 

 distributors in Chelan and Okanogan 

 Counties of the Security ladder, said to 

 be the one ladder made on the Coast 

 which Florida citrus growers send 

 across the continent for. 



