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BULLETIN 1371, U. S. DEPARTMENT OP AGRICULTUEE 



greater strength was more effective this increase was not in the same 

 ratio as the increase in dosage. 



The infestation in this orchard was not very heavy but even under 

 these favorable conditions the 12.5-pound dosage allowed over 5.5 

 times as many young scales to settle on the new wood as did the 

 liquid lime-sulphur. 



Table 17 .—Results of tests with dry sodium-sulphur sprays against the San Jose 

 scale on peach trees at Canton, Miss., in 1923 





Quan- 

 tity 

 in 50 



gallons 

 of spray 



Hibernating 

 scale 



Infestation of young scale on 80 linear 

 inches of new wood 



Material used 



First generation 



Second generation 





Dead 



Control 



Num- 

 ber 

 of 



scales 



Aver- 

 age 

 per 



inch 



Per- 

 centage 



of 

 check 



Num- 

 ber 

 of 

 scales 



Aver- 

 age 

 per 



inch 



Per- 

 centage 



of 

 check 



Sodium-sulphur No. 3 



Do -. 



Pounds 

 12.5 



26. 625 



Oallons 



6.66 



Percent 

 53.0 

 71.0 



96.4 

 16.2 



Percent 

 43.9 

 65.4 



95.7 



353 

 247 



39 

 1,022 



4.41 

 3.09 



.49 



12.78 



34.5 

 24.2 



3.8 



525 

 365 



92 

 1, 262 



6.56 

 4.56 



1.15 

 15.78 



41.6 

 28 9 



Liquid lime-sulphur ' 



Check 



7.3 









1 Baume 31.8°. 



The experiments discussed in Table 17 were carried on during 

 a season when the scale was not increasing so rapidly as in 1922, 

 and all of the treatments gave better control than in the previous 

 season, but the relative efficiency is much the same. 



It is of interest to note that in the first experiment, in spite of the 

 43.9 per cent control, the second count of young scales showed 41,6 

 per cent, as many as were found on the untreated checks. 



DISCUSSION OF RESULTS 



When used at the strength ordinarily employed (12.5 pounds 

 to 50 gallons) the average control on hibernating scales was 30 per 

 cent. When this dosage was increased to 25 to 27 pounds the control 

 only rose to 58.3 per cent. In the same set of experiments liquid 

 lime-sulphur gave an average control of 83.6 per cent. 



These figures are supported by the counts of first and second 

 generations of young scales on the new wood, since in every case 

 many more were found in the sodium-sulphur plats than where liquid 

 lime-sulphur was used. 



SUMMARY 



The experiments with the dry sodium-sulphur sprays show, on the 

 whole, results that are very similar to those obtained with the dry 

 calcium-sulphurs. In no case were they as effective as liquid lime- 

 sulphur, even when used at greatly increased strengths, and it can not 

 be considered that they furnished a satisfactory control of the San 

 Jose scale. 



These experiments covered a period of three years, and were carried 

 on in three different States under widely varying conditions. 



