UNIVERSITY OF CALIFORNIA. 
 
 AGRICULTURAL EXPERIMENT STATION. 
 
 BULLETIN NO. 52. 
 
 Alkaline Washes for Fruit Trees. 
 
 rest, even though soluble in water, are to be 
 considered as impurities of little or no practical 
 
 ; value to him. From this point of view the 
 
 In response to numerous inquiries regarding "Philadelphia solid lye" should be let severely 
 the relative strength and merits of the several alone, two- thirds of it being common salt, which 
 materials for alkaline tree washes, now offered any one can put in for himself if so inclined, 
 in the market, I give below the results of the Tor tree- washing, however, salt is no manner of 
 analysis of five of the most prominent, lately consequence, and is often in the way of other 
 made at the agricultural laboratory of the Uni- materials that may advantageously be combined 
 versity. No. 6 gives the usual composition of with the lye in some cases, e. g. soap. 
 Canadian crude potashes, as found in commerce, The "American concentrated lye" is a bona 
 and may be taken as representing that of the f-de preparation, resulting from the treatment 
 lye of wood ashes when boiled down. It is the of co nine -cial soda ash with lime. We have 
 
 * found it to range as high as 90 per cent of 
 caustic soda, and 80 is probably as low as it 
 goes. 
 
 The English "double concentrated 08 per 
 cent caustic soda," from the Greenbank works 
 is an unusually pure product, exceeding, as the 
 analysis shows, even what is claimed in its 
 name for its percentage of effective caustic. 
 
 A glance at the "caustic soda" percentages 
 will show good reason why some perbons, when 
 T. W. Jackson^ using "one pound per gallon" of water, fail 10 
 kill the scale, while others not only kill the 
 
 material from which No. 5, the " commercial 
 caustic potash " is made by treatment of lime. 
 
 Composition of Commercial Alkalies. 
 1. — " Philadelphia solid lye," sent by R. 
 
 San 
 
 Wheeler, Fresno 
 
 2. — American concentrated 4 lye, from 
 Francisco agencies. 
 
 3. — Double concentrated, 98 per cent caustic 
 soda, from Greenbank Alkali Works Company, 
 St. Helens, Lancashire, ,Eng 
 agent in San Francisco. 
 
 4.— Refined pearl ashes, same manufacturer, scale, but severely scorch the trees. It would 
 Commercial potash, Langley & Michaels, take just Jive pounds of "Philadelphia solid" to 
 
 San Francisco 
 
 6. — Canadian crude potashes, commercial 
 
 1 
 
 0 
 
 22.7 SO. 4 
 
 99.3 
 
 66.6 
 J 
 
 69.1 
 
 52.3 
 
 16.8 
 
 5.9 
 
 4.9 
 
 be equal in effect to one pound of the Green 
 bank 'double concentrated," or to one and a 
 quarte* of the "American concentrated." 
 
 Again, if a wash containing a pound of the lat- 
 ter to a gallon of water is used warm, it will 
 kill the scale and may leave the tree unharmed, 
 while a similar proportion of the "double con- 
 centrated" would scorch the tree if used hot, 
 but might leave it unscathed when applied cold. 
 A pound of the "Philadelphia" would be harm- 
 less to an} thixig but a young scale just hatched 
 and moving. Hence the wide differences in the 
 experience of different persons is readily ex 
 plained on this ground alone. 
 
 But there are several other causes for these 
 differences. One of the most common is that a 
 strong lye, say a pound to the gallon, may be 
 14 4 applied with impunity to trees that have never 
 been sprayed and are full of moss and old bark, 
 2 7" which, dissolving in the lye, weakens it ma- 
 ^ ~ terially. The same lye applied to a clean tree 
 — will in reality remain considerably stronger, and 
 ine three first numbers represent, or should ma Y scorch it. 
 represent, the basis of the lye washes for fruit Another, and incredibly common cause of 
 trees, the active part being the "caustic soda" difficulty is the failure to make all the solid lye 
 or some hydrate, preferred to the correspond dissolve and form a uniform solution before 
 ohlJ^T 9h T , com P° und simply because it is using it. When, as is very commonly done, 
 that tt\' a .t„L P urc j laser should understand the drums are merely burst open with a hatchet, 
 that this caustic soda is all that he wants to the lumps of soda lye cracked a little, then 
 
 Caustic Soda 
 
 Caustic Potash . . 
 
 Carbonate of Po 
 tash 
 
 Chloride of Po 
 tassium 
 
 Chloride of So 
 dium 
 
 Carbonate of So- 
 da 
 
 Sulphate of Soda 
 
 Sulphate of Po 
 tash 
 
 Silica 
 
 Insoluble Residm 
 
 Moisture 
 
 ..\13.2 
 
 6.4 
 
 .5 
 
 23.8 
 
 14.8 
 
 7.5 
 .1 
 2.1 
 1 
 
 71.4 
 3.6 
 
 2.3 
 
 pay for when tree-cashing is his object. 
 
 The thrown into the boiler and water poured on 
 them, it takes a great deal of time, boiling, 
 
stirriog and patience to make the result corres- 
 pond with what the prescription intended. A 
 dense, heavv. oilv solution will form over the 
 bottom, and with a strong fire there will be a 
 great deal of spluttering and bumping there; 
 but the lumps obstinately refuse to dissolve 
 with any reasonable degree of rapidity, and 
 when the workmen find that the water above 
 is pretty sharp in its action on their hands, 
 they think it will do for the scale also, and off 
 it goes into the spray pump. When they come 
 down to the bottom of the boiler, the lye is 
 "double concentrated" in dead earnest. It is 
 extra hot, too. When this last lot goes on the 
 trees the scale goes, of course, but the bark of 
 the tree also. On the other hand, the scale 
 continues to flourish where the first weak part 
 of the lye was applied, and the general outcome 
 is as unsatisfactory as the worst grumbler could 
 desire. 
 
 All such difficulties can be easily avoided, 
 and a great deal of time saved, by putting the 
 solid lye on a (tin or sheet-iron) perforated shel- 
 or colander, so placed that the lye will be near 
 the surface of the water instead of at the bot- 
 tom. Then, when a lively boil is set up, there 
 ill be no spluttering. The lumps will dis- 
 solve in the shortest time that their size per-, 
 mits, and the result will be a solution of uni- 
 form temperature and strength throughout. 
 
 Precisely the same rule applies to the potash! 
 compounds, given in Nos. 4, 5 and 6. The 
 chief reason for using the latter at all, not-j 
 withstanding their higher price, is, that being; 
 "deliquescent," that is, attracting water and 
 spontaneously forming a permanent solution, by 
 simple exposure to the air, they serve to main- 
 tain the corrosive action for a greater length of 
 time than would the soda lye alone, unless un- 
 der exceptionally favorable conditions. 
 
 In examining trees that have been sprayed 
 with soda lye alone on a sunny day, it will 
 sometimes be found that within an hour after 
 the spraying, the dry portions are covered with 
 a network of small, white needles, resembling 
 white frost. These needles are simply solid 
 carbonate of soda, and show that by the action 
 of the dry air, the "causticity" of the lye has 
 been quickly destroyed. The bland, common 
 salsoda has taken its place, and the action is 
 practically at an end. 
 
 It is quite otherwise when the spraying has 
 been done on a moist or foggy day, or late in 
 the afternoon, so that the lye remains in a 
 liquid condition. It then goes on working for 
 many hours, eating away the edges of the old 
 scale, and finally reaching to the old insect or 
 eggs inside; and, should favorable weather 
 continue, the toughest old inhabitant may thus 
 be destroyed in a single application. 
 
 The use of the potash compounds in connec- 
 tion with the soda lye aids materially in main- 
 taining the active corrosion more or less inde- 
 pendently of moist weather, by preventing the 
 rapid evaporation and solidification that so often 
 puts a premature end to it. Moreover, the pot- 
 ash compounds so used ultimately reach and re- 
 
 , 
 
 main in the soil, and act as a fertilizer when 
 needed, so that the money spent on them is not 
 gone with the insects. 
 
 Of the three commercial potash compounds, of 
 which the composition is given above, No. 5, the 
 "commercial caustic potash" is the most' effect- 
 ive. It might, of course, be used alone, but for 
 its higher price and lower grade of caustic, 
 which would make such use rather expensive. 
 To secure the point desired, viz., the mainte- 
 nance of the fluidity of the wash in dry weather, 
 it is sufficient to use half as much as of the soda 
 lye. From my personal experience, I recom- 
 mend one pound of the "American concentrated 
 lye , or four -fifths pounds of Greenbank "double 
 concentrated ," and half a pound of the "com- 
 mercial potash" to two gallons of water as the 
 strongest wash necessary to be used, and still 
 safe, on all dormant trees; in bad cases to be 
 used hot, so as to show 140° in the tank when 
 it will reach the tree at 110° or thereabouts, 
 varying according to the fineness of the spray 
 and the dryness of the air. The finer the spray 
 and the drier the air, the more the fluid will be 
 cooled before it reaches the tree. 
 
 Instead of the 'commercial caustic potash," 
 No. 5 of the table, Nos. 4 or 6 may also be 
 used, if more conveniently obtainable. In that 
 case, however, § pound instead of h should 
 1 be used with each pound of solid soda lye, and 
 two gallons of water. 
 
 The addition of a tablespoonful of sulphur 
 per pound of lye during the boiling is probably 
 useful and should be tried. When consulting 
 economy in the use of these washes, it should 
 be remembered that fine spray is much more 
 economical than coarse droplets, of which a 
 large proportion falls to the ground before a 
 wetting of the whole tree surface can be assured. 
 A fine jet with heavy pressure is required j or fine 
 spray* In the case of large trees where drops 
 from above are caught by the lower branches, a 
 "San Jose" nozzle with ordinary pressure is 
 perhaps as economical as any ; but for small 
 trees from which all that does not stick to the 
 bark falls to the ground, the fine spray from a 
 "Cyclone"or "Imperial" nczzle under high pres- 
 sure is more economical. 
 
 Many persons cut back their trees severely, 
 in order to induce a clean new growth, and 
 also save expense in spraying. It should not 
 be forgotten that the strong lye falling on the 
 open cuts causes the 3tumps to die for one, and 
 sometimes several inches below the cut nnless 
 the latter are waxed over. As the infested 
 brush remains for some time a source of danger 
 from re-infection unless promptly dealt with, 
 it is often questionable whether it is not cheap- 
 er to include it in the spraying and prune 
 afterward, rather than to run that risk. 
 
 In the preparation and use of the several tree 
 washes, there is abundant room for the exercise, 
 not only of common sense, but even for that of 
 uncommon acumen, if good and uniform results 
 are to be obtained. It is not at all surprising 
 that numerous failures should occur when the 
 matter is left to untrained workmen alone, with 
 such miscellaneous materials as are shown in 
 the above table of analysis. 
 
 Berkeley, Feb. 6', 1886. E. W. Hilgard. 
 
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