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. /