352 Report op the Horticultural Department of the 



germination of pollen and the growth of pollen tubes were made 

 in the laboratory; and in the orchard the effects of spraying 

 the trees when in full bloom were observed. 



The spraying mixtures and even the lime alone prevented the 

 growth of pollen in weak aqueous solutions of sugar. 



In Bordeaux mixture, 1 to 11, diluted with a weak aqueous 

 sugar solution to only 200 parts in 10,0T)0, pollen rarely germi- 

 nated; 100 parts in 10,000 in some cases wholly prevented the 

 germination of pollen; 50 parts in 10,000 in some cases wholly 

 and in others partly prevented the germination of pollen, aud 

 always much retarded and dwarfed the growth of the pollen 

 tubes. Even 2 parts in 10,000 sometimes had an adverse influ- 

 ence on the germination of the pollen. 



Where apple blossoms, in the earlier part of the blooming 

 season, were hit by a spray of Bordeaux mixture combined with 

 an arsenical compound, they generally failed to set fruit. Blos- 

 soms which had been open several days before they were hit 

 by the spray seemed to have reached a stage where this treat- 

 ment did not check the setting of fruit. Apparently conflict- 

 ing results are reconciled by a clear understanding of this point. 

 There is a great difference between young blossoms and old blos- 

 soms in their susceptibility to injury by spray mixtures. 



By spraying repeatedly during the 'blooming season, thus 

 hitting the new blossoms as they opened from day to day, the 

 blossoms were nearly all destroyed and as a consequence scarcely 

 any fruit set. 



A number of sprayed blossoms were observed which had some 

 of the spray mixture on the stigmatic surface, l^one of these 

 set fruit. 



During the season of 1900 the orchards under experiment were 

 so free from attacks of apple scab and other fungous diseases 

 that no information was gained as to whether or not such dis- 

 eases may be controlled better by spraying in bloom than by 

 earlier and later treatments. 



Even with trees which had a great abundance of blossoms 

 spraying but once during the blooming season decreased the 



