DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 39 



Dusting or spraying was done at five different periods 



as follows : 



1st. Just as the leaf buds were opening. 



I'nd. As the fruit was forming. 



.'Jrd. Ten days after second application. 



4th. Two weeks after third application. 



~)th. 0011 after fruit was harvested. 



The dusted plot only was treated at the fourth application. The 

 fruit was so nearly ripe at that time that any spraying material would 

 have spotted the fruit badly. 



No arsenical was used for the third, fourth and fifth applications on 

 tin' sprayed plots. For the fourth and fifth applications straight sul- 

 pliur was used on the dusted plot. 



RESULTS 



I\<'xixt<uicc to Disease. There was a great difference in the resistance 

 of the different varieties to anthracnose. A partial list follows. This 

 is based upon the time and severity of disease development on check 

 plants. 



Prince Albert Very resistant. 



London Market Resistant. 



Wilder Susceptible. 



Perfection Susceptible. 



Fay's Prolific Susceptible. 



La Versa iles Susceptible. 



Cherry Susceptible. 



Red Cross Susceptible. 



Red Dutch Very susceptible. 



Prince Albert was practically free from disease throughout the sea- 

 son. London Market was not so resistant as Prince Albert. It held 

 its foliage quite well until about September 1st, but lost considerable 

 foliage after that time. 



Wilder, Perfection, Fay's Prolific, LaVersailles, Cherry and Red Cross 

 were quite susceptible to anthracnose and untreated plants lost their 

 foliage quite early. 



lied Dutch was very susceptible and untreated plants were entirely 

 defoliated early in July. 



Foliage Injun/. The foliage of all plants sprayed with bordeaux was 

 in excellent condition throughout the season. There was no physical 

 injury and the leaves were vigorous and dark green in color. 



The foliage of dusted plants was severely injured by the sulphur. 

 Many plants lost much foliage because of this injury. The remaining 

 leaves were light green in color and not so vigorous as where bordeaux 

 was used. 



Dilute lime-sulphur produced the same condition as the dusting sul- 

 phur. Defoliation was severe and the color of the leaves was not good. 



Injury of this nature probably would not be so severe during a cooler 

 season. Sulphur injury usually occurs when the temperature is high. 

 Conditions' in a currant plantation are probably favorable to such in- 

 jury as the plants are low and close together so that there is not much 

 circulation of air. 



