154 Report of the Botanist of thk 



With all of these plants the trouble is not due to a gi-adual 

 drying-, hut to a sudden scorch;ing by the transpiration of more 

 water from the leaves than the roots are able to supply. 



INTRODUCTIOX. 



It is not an uncommon thing for the foliage of various plants 

 to be injured by excessive transpiration. Such injury may be 

 brought about in either of two ways: (1) By a process of gradual 

 drying, such as occurs in plants suffering from drought, and (2) 

 By sudden scorching, as when a fire is built under a tree. With 

 the first kind of injury every one is familiar and those living in 

 the arid and semi-arid portions of om* country have frequently 

 observed the latter kind. In Kansas, for example, dry, hot south- 

 west winds often ruin promising crops of com in two or three days. 



But here in the East, the sudden scorching of foliage by hot 

 wind and sun is of such rare occurrence that it attracts attention 

 and is generally misimderstood by farmers and fruit growers. It 

 is frequently mistaken for infectious disease. The object of this 

 bulletin is to place upon record some observations on the sudden 

 scorching of the foliage of sugar beet, cherrj'', cauliflower and 

 maple, due to excessive transpiration. 



LEAF SCORCH OF SUGAR BEET.^ 



About the middle of August, 1899, some farmers in Yates and 

 Ontario counties wrote to the Station that their sugar beets were 

 blighting. On August 29, the wiiter visited several of the af- 

 fected fields and found the so-called blight to be cbaracterized 

 as follows: On slightly affected plants the only indication of dis- 

 ease was to he seen in the brown or black, dead leaf margins. In 

 more severe cases the young leaves at the center of the crown 

 were black and dead, as were also the blades of most of the leaves. 

 j\Iany plants showed nothing gTcen but the petioles of the larger 



1 For the illustrations used in this bulletin, the author is indebted to Mr. 

 F. H. Blodgett, Assistant Botanist and Entomologist. 



