86 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



tides had been fully determined these plots have been intro- 

 duced solely for the purpose of checks to serve, together with 

 the unsprayed plot, as a basis of comparison with other sprays 

 and spray combinations with respect to scab control and the 

 production of fruit russeting and foliage injury. They have, 

 however, given some very striking data as to the comparative 

 value of the two materials when used on a variety of apples 

 which is particularly susceptible to spray injury. 



Lime-sulphur at the dilution mentioned has sometimes given 

 a little leaf injury but never sufficient to be of economic im- 

 portance. When compared with the unsprayed check plot this 

 treatment has increased the number of russeted apples from 

 5 to 10 per cent during the past 3 seasons. Scab control has 

 been less than with bordeaux mixture but the greatest differ- 

 ence has been only about 3 per cent. 



Bordeaux mixture on the other hand has caused serious leaf 

 injury nearly every year for the past 6 seasons, frequently 

 resulting in partial defoliation of the trees. Its greater effi- 

 ciency in scab control has been discounted several times over 

 by the increased fruit russeting produced. In the past 3 years 

 the per cents of merchantable apples on the plot sprayed with 

 bordeaux mixture have been in round numbers, 30, 10, and 21, 

 respectively. At the same time the unsprayed check, not even 

 treated with an insecticide, gave 30, 87, and 91 per cent ot the 

 same grade of fruit. In other words, based on the quality of 

 the fruit produced, nothing was gained the first year and heavy 

 losses resulted the next two years from spraying Ben Davis 

 trees with 3-3-50 bordeaux mixture. 



The effect of different dilutions of lime-sulphur : The ques- 

 tion of the effect of different dilutions of lime-sulphur in con- 

 trolling scab and in the production of spray injury was one of 

 the first problems to be studied. A spray containing 25 per cent 

 less concentrate than the standard dilution was tried for two 

 years, in but one of which was scab very prevalent. That year 

 the plot treated with the weaker spray produced 13 per cent 

 more scabby fruit than was orJtained where the standard dilu- 

 tion was used. The matter was not followed farther for it was 

 evident that this weaker dilution would prove inefficient. 



A comparison between standard dilution lime-sulphur and one 

 20 per cent, stronger was carried on for 4 consecutive seasons. 



