THE POTATO 191 



ditions surrounding the plant. Long-continued, 

 cloudy and damp weather followed by several hot 

 and bright days is very apt to result in the burn- 

 ing of the foliage. This is especially the case on 

 soils carrying a comparatively small percentage of 

 moisture. When the weather is cloudy and damp 

 the tissues of the potato become gorged with water 

 and this has a tendency to weaken them. If the 

 sun appears bright and hot when the leaves are in 

 this condition there is a rapid evaporation of the 

 moisture stored up in their cells. The evaporation 

 may be faster than the supply furnished by the 

 roots, and if this continues for any length of time 

 the weaker and more tender parts first collapse, 

 then die, and finally turn brown and dry up. Tip 

 burn may also occur as a result of protracted dry 

 weather. 



"Little of a specific nature can be said on the 

 treatment of this trouble. Numerous factors are 

 involved in the matter, so that only general state- 

 ments are possible. Every effort should be made 

 to keep the plants in good growing condition, for 

 if they become checked through lack of proper food 

 or cultivation, or both, they are more apt to burn. 

 It is a fact that where the Bordeaux mixture is 

 used for other diseases burn is less apt to occur, 

 and this furnishes another instance of the remark- 

 able properties of the fungicide. Briefly, therefore, 

 the plants should be kept as vigorous as possible 

 by good cultivation, plenty of available food, 

 and the application of Bordeaux mixture as recom- 

 mended for early blight. 



"In many sections where Paris green in water is 

 applied to potatoes, injuries are produced which 

 cannot be distinguished from early blight by an 

 ordinary examination. It frequently happens. 



