Burning 



that many different plants are suffering from the 

 spotting, though the spots are not all of the same 

 shade of yellow or brown, whereas a fungus attack 

 will be confined to one or at most a few kinds of 

 plants in it, as with that of most animal attacks 

 except perhaps red spider, when the pests themselves 

 will be evident to the careful observer. This will 

 serve to distinguish the source of this trouble from 

 that of insect or fungus attack in most cases, but 

 not from the trouble known as burning or scalding. 



The escape of coal-gas or acetylene from leaks in 

 underground pipes not infrequently leads to the 

 death of roots of trees and shrubs in the vicinity. 



Burning or scalding is characterised by the 

 presence of white, yeUow, or brown spots on the 

 foUage (only occasionally at the edges) and is most 

 frequent on leaves of rather thin texture. It 

 occurs also on grapes. It is often attributable to 

 defective glass (i.e. glass of uneven thickness, or 

 containing bubbles) concentrating the sun's heat on 

 certain spots, and plants placed in these spots will 

 suffer. Similar results follow even a short time of 

 water shortage in some deKcate-leaved plants such 

 as Primulas and Begonias, especially when the air as 

 well as the soil is dry, or lack of ventilation with 

 vines, etc., or syringing with a falling temperature 

 instead of with a rising one, which is particularly 

 detrimental to orchids and leads to the black- 

 spotting of the foliage or pseudo-bulbs. Exactly 



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