Page 10 



BETTER FRUIT 



July, igiQ 



Dry Lime and Sulphur as Compared to Liquid 



By A. L. Melander, Washington State College, Pullman, Washington 



DRY spraying materials are more ■will have more insoluble material than 

 convenient to transport and keep a fresh lot. It is claimed that this in- 

 than liquid or paste sprays, and hence soluble material sometimes obstructs 

 as a matter of trade competition manu- strainers and nozzles. If the dry lime- 

 facturers have been desirous of placing sulphur is boiled in water more or less 

 such materials on the market. In the of the sulphur goes again into chemical 

 case of the sulphur-made sprays, two solution. A recent analysis by the State 

 dry forms are being made, one where Chemist of Washington showed in 

 the sulphur is combined with soda and round numbers the following interest- 

 sold under the trade names of Soluble ing facts: 



Sulphur Compound and Spraysulphur, in Cold in Boiling 



the other a true lime-sulphur manufac- insoluble ^7%' ^"1% 



tured by the Sherwin-Williams Com- Poiysuiphid sulphur 42% 59!o% 



„nf,v Thiosulphate and other 



r ., 1 J /. ,. , , combined sulphur 8% 5.0% 



In the early days of lime-sulphur Lime 25% 26.0% 



each fruit grower had to make his own Sugar 2% 2.0% 



spray, cooking it in diluted form be- The Sherwin - Williams Company 

 cause with existing recipes a strong claims that the sugar stabiUzer en- 

 lime-sulphur would crystalize. Then hances the value of its product when 

 by modifying the formula it became sprayed on the trees. We know that a 

 possible to prepare hme-sulphur in con- solution of dry lime-sulphur will not 

 centrated form, and factories took to oxidize as rapidly as the standard 

 making strong lime-sulphur solution for liquid lime-sulphur, but this may be 

 shipment. Whenever the attempt was regarded as a theoretical disadvantage 

 made to increase the concentration rather than an advantage, if the insecti- 

 further or to cook to dryness the lime- cidal value of lime-sulphur is due to its 

 sulphur changed chemically, taking up ability to absorb oxygen. Until this 

 oxygen and throwing out sulphur, and point is proved it would be unwise to 

 was so disintegrated as to be nearly be influenced by this argument, 

 valueless. The Sherwin-Williams Com- The printed leaflets distributed by the 

 pany, however, discovered a most in- Sherwin-Williams Company state that 

 genious and practical method of pre- "a barrel of liquid lime-sulphur solu- 

 paring lime-sulphur in dry form. A tion weighs approximately 600 pounds, 

 small amount of sugar added to a highly and 80 to 100 pounds of Sherwin- 

 concentrated lime-sulphur solution was Williams dry lime-sulijhur will accom- 

 discovered to retard the chemical disin- plish the same results." This statement 

 tegration, so that the liquid could then is obviously fallacious, but is made in 

 be evaporated in vacuo and marketed order that a 100-pound drum of the dry 

 in powder form. material can compete in selling price 



When lime, sulphur and water are with the barrel of liquid. A barrel of 

 boiled together a series of progressive standard lime-sulphur concentrate con- 

 chemical reactions take place, whereby tains approximately 135 pounds of sul- 

 the original ingredients are changed, phur and 65 pounds of lime in solution 

 principally into calcium sulphids, cal- in 320 pounds of water. All 200 pounds 

 cium polysulphids, calcium thiosul- of the ingredients are soluble and there 

 phate, calcium sulphite and calcium is the maximum amount of poiysuiphid 

 sulphate. When the lime is in chemical sulphur immediately available. In the 

 excess (i e., more than half as much drum of dry lime-sulphur there are 

 lime as sulphur), the relative amount of about 65 pounds of actual sulphur and 

 thiosulphate is increased. WTien the 26 pounds of lime, but of the 100 total 

 sulphur is in chemical excess (i e., more pounds about 20 pounds consist of sugar 

 than twice as much sulphur as lime), or material insoluble in cold water, 

 the relative amount of poiysuiphid is Unless there is evidence to the contrary 

 increased. The best grades of lime- a pound of calcium poiysuiphid should 

 sulphur have the largest amount of poly- be regarded as a pound, whether sold in 

 sulphid present, amounting to about 90 dry form or dissolved in water, 

 per cent. When lime-sulphur is applied On the basis of actual sulphur con- 

 as a spray it takes on oxygen; the poly- tent it would take two drums of dry 

 sulphid is converted into thiosulphate, lime-sulphur to be equivalent to a bar- 

 the thiosulphate into sulphite and rel of concentrated liquid, unless the 

 finally the sulphite into sulphate. It is material is boiled into solution two and 

 this chemical change that is supposed one-half drums would be a closer equiv- 

 to give to lime-sulphur its value as an alent. On the basis of similar strengths 

 insecticide, for the taking up of oxygen of spray solution, therefore, the cost of 

 is a sort of chemical suffocation. Ob- dry lime-sulphur at present prices is too 

 viously, then, the polysulhpid is the great to offset the possible advantages 

 most valuable ingredient, for it can take of the dry over the liquid, 

 on more oxygen than the other chem- During' 1917 and 1918 the Washing- 

 icals further along in the series. ton Experiment Station carried on some 



\^^len Sherwin-Williams dry lime- comparative spraying tests on the San 



sulphur is dissolved in cold water a Jose scale, in which the dry lime-sul- 



certain amount always remains as sedi- phur was used. These tests indicate 



ment. This sediment consists of sul- that the Sherwin-Williams product has 



phur and more or less chalk, possibly merit, comparing well with the equiv- 



of value against mildew, but of no alent strengths of the standard liquid 



worth against scale or aphis. An old form. The fact that the Sherwin- 



sample, or one that has been opened, Williams Company can adduce testi- 



monials showing beneficial effects from 

 a weak spray can be paralleled with 

 almost any insecticide. We have re- 

 peatedly noticed surprising results 

 from extremely weak solutions, but no 

 one feels ready seriously to recommend 

 ultra-weak sprays for general practice. 

 The fruit grower who depends upon 

 using ten pounds of dry lime-sulphur 

 to fifty gallons is taking a big risk. The 

 weakest lime-sulphur that can be gen- 

 erally recommended for winter spray- 

 ing tests three degrees, by the Baume 

 hydrometer, and contains about ten 

 pounds of sulphur and five pounds of 

 lime in each fifty gallons. This is 

 equivalent to a dilution of three and 

 one-half gallons of factory-made con- 

 centrate in fifty gallons. To produce a 

 similar strength nearly twenty pounds 

 of dry lime-sulphur would be ordinarily 

 required unless the material were 

 boiled into solution, in which case a 

 trifle over fifteen pounds would suffice. 

 Weighing the pros and cons in com- 

 paring liquid and dry lime-sulphur the 

 advantages of the dry form consists in 

 convenience in transportation and 

 avoidance of worries about freezing 

 and leakage. The disadvantages in- 

 clude expense, possibility of deteriora- 

 tion, difliculty of solution and waste of 

 valuable sulphur unless the powder is 

 boiled into solution. 



Fruit Growers' Convention 



The Fifty-first Fruit Growers' and 

 Farmers' Convention, recently held at 

 Riverside, California, was one of the 

 largest representative gatherings of 

 fruit and vegetable growers, horticul- 

 tural experts and horticultural inspec- 

 tion officials ever held in the West. 



The convention meetings were held 

 in the cloister and gymnasium of the 

 Mission Inn. Programs were carried out 

 by the Fifty-first Fruit Growers' and 

 Farmers' Convention, Interstate Plant 

 Quarantine Conference, California 

 County Horticultural Commission, Con- 

 vention of California Association of 

 Nurserymen, State Vegetable Growers' 

 Conference and Pacific Coast Economic 

 Entomologists. In addition to the dele- 

 gates who were present from the West- 

 ern states, Hawaii, New Zealand, Lower 

 California and British Columbia were 

 represented. 



The discussions were of great impor- 

 tance to fruit growers and farmers in 

 the Pacific Northwest. Among the sub- 

 jects that were taken up were: Market- 

 ing methods of fruit and vegetable pro- 

 duction; quarantine and methods of 

 control of horticultural and agricul- 

 tural pests, including boll worm of cot- 

 ton, cotton boll weevil, alfalfa weevil, 

 citrus canker and other horticultural 

 pests. 



One of the results of the conference 

 was the organization of the Association 

 of Western Quarantine Ofiicers, which 

 was formed to further unify and protect 

 the Western states against crop pest in- 

 vasion. Discussions of uniform grades, 

 packs and packages for horticultural, 

 agricultural and livestock products was 

 one of the most important subjects 

 considered. 



