Proceedings, 1913. 



11 



combinatious oC lime-sulphur autl acid arsenate; of lead, lime-sulijhur aud neutral 

 arsenate of lead, and lime-sulphur aud arsenite of zinc. These experiments were to 

 be continued through three seasons in order to get checks on all data. 



Several factors entered to interfere with the first season's work, so that the 

 results were very unsatisfactory and detailed data is not worth mentioning. In 

 going over the notes at the end of the season, however, several interesting facts 

 were noted and are here summarized. 



(1.) Lime-sulphur 29..5° Be. (1-301 + acid arsenate of lead 2 lb. to 00 gallons 

 (lid not cause any more spray injury to foliage and fruit than did the lime-suliihur 

 and neutral (spray injury was quite bad on Newtowns and Ben Davis). Injured 

 fruit was worst on south side of tree and in direct rays of sun. 



(2.) Lime-sulphur 29.5° Be. (1-30) + arsenite of zinc 1 lb. to 50 gallons (two 

 different brands) did not cause but very little injury to foliage, and except in the 

 case of Ben Davis did not cause any more injury to the fruit than was found on 

 unsprayed trees. (Ben Davis suffered badly.) The injured fruit on these trees 

 was worse on south side of tree. 



(3.) Injured apples similar to those on the spra.ved trees could occasionally 

 be found on unsprayed trees in the check plot, but the difference in pin-centagc 

 was so great that we must conclude that the injury on the spr.-iycd trees had in 

 some way been caused by the spray. 



In 1012, in connection with the above experiments, a series of experiments were 

 started upon the decomposition of combined sprays when allowed to stand. The 

 materials in each case were kept in corked bottles and examined from time to time 

 during the following year. Apparently no further change occurred and each 

 combination retained its characteristic odour. An examination on .Tune 1st, 1913. 

 gave the same conditions and tests for the insecticidal values aud showed them to 

 be apparently as eflicient as freshly prepared materials. 



Observations for the present season's work show some startling results, and on 

 account of this a number of them were immediately checked. The same results 

 were obtained in both cases. 



The arsenates of lead used in these experiments were specially prepared by the 

 Station Chemist, and were, according to methods of determination that will be 

 published in the near future, theoretically pure. 



^ The lime-sulphur was known as the Dependable Brand, made at 8alem, Ore., 

 and when analysed w^as found to be satisfactory in every particular. The arsenite 

 of zinc used was manufactured by the California Spray Co., at Watsonville, 

 California. 



To determine the effect upon apple-foliage of the above chemicals alone and in 

 combination, a series of experiments were conducted as follows : A block of twenty 

 Newtown apple-trees was taken and each tree was used for one spray. 



In 1913, under press of other work, the Department of Plant Pathology discon- 

 tinued their part of the work, and so the investigations this year have not included 

 the study of fungicidal values. 



The Experiments were as follows : — 



■jxpcritiients on the Decomposllion of Coiiihiiicd S/icni/.s irhcn allowed to stand. 

 * Sjjrays combined as follows on Man 2i)lli, 1SI2. Lune-sulphur used in these 

 Experiments tested 2S.t5 Be. 



(1.) Lime-sulphur 17.5 cc. 



Black Leaf 40, 1-1,000. .482.5 cc. 

 Aisenate of lead, non- 

 acid (C.S. Co.) 2.4 gms. 



C.S. Co. — California Chemical 

 Spray Co., Watsonville, Cal. 



.May 29tli. Combined the above materials on 

 morning of this date. At 3 p.m. residue 

 settled in bottom, changed from white to a 

 grey. The odour of the Black Leaf 40 and 

 'the lime-snlphur are readily distinguished. 

 The solution retaintKl its amber colour and 

 resembled lime-sulphur diluted to the same 



* Materials combined at the rate of : Lime-sulphur 1 to 30 ; arsenicals at 2 It), to TiO 

 gallons for neutral and 1 It), to 50 gallons for tlie arsenate of load acid and the arsenite 

 of zinc. 



